I have a problem with btn.setOnClickListener(this). I have a simple project that works good, but when I add an action to the button I get the message:
unfortunatelay (app name) has stopped
When I comment btn.setOnClickListener(this) out the project works without any problem.
Here is my code:
package com.example.hello;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v7.app.ActionBarActivity;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.widget.Button;
public class MainActivity extends ActionBarActivity {
public static final Context PlaceholderFragment = null;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
if (savedInstanceState == null) {
getSupportFragmentManager().beginTransaction()
.add(R.id.container, new PlaceholderFragment()).commit();
}
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
/**
* A placeholder fragment containing a simple view.
*/
public static class PlaceholderFragment extends Fragment implements OnClickListener {
Button btn;
public PlaceholderFragment() {
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_main, container,
false);
btn=(Button)rootView.findViewById(R.id.Entrer);
btn.setOnClickListener(this);
return rootView;
}
#Override
public void onClick(View v) {
// here is the problem error: no eclosing istance of the type MainActivityis accessible in scope
Intent intent = new Intent(MainActivity.this, SecondActivity.class);
startActivity(intent);
}
}
}
My layout is as follows:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="#dimen/activity_vertical_margin"
android:paddingLeft="#dimen/activity_horizontal_margin"
android:paddingRight="#dimen/activity_horizontal_margin"
android:paddingTop="#dimen/activity_vertical_margin"
tools:context="com.example.hello.MainActivity$PlaceholderFragment" >
<TextView
android:id="#+id/textView1"
android:layout_width="300dp"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_marginTop="190dp"
android:text="#string/hello_world"
android:textSize="16dp" />
<Button
android:id="#+id/Entrer"
android:layout_width="300dp"
android:layout_height="wrap_content"
android:layout_below="#+id/textView1"
android:layout_centerHorizontal="true"
android:layout_marginTop="61dp"
android:text="Entrer" />
</RelativeLayout>
I dont know if I have simple things that are not go correctly. I'm new to Android programming. Thank you!
btn is null, so when you set onClickListener you get NullPointerException. It's null because it's located in fragment_main.xml, not activity_main.xml. You should move this code from onCreate()
btn = (Button) findViewById(R.id.Entrer);
btn.setOnClickListener(this);
to PlaceholderFragment() as follows:
public static class PlaceholderFragment extends Fragment {
public PlaceholderFragment() {
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_main, container,
false);
btn=(Button) rootView.findViewById(R.id.Entrer);
btn.setOnClickListener( new View.OnClickListener() {
#Override
public void onClick(View view) {
Intent intent = new Intent(getActivity(), SecondActivity.class);
startActivity(intent);
}
});
return rootView;
}
}
btn=(Button)findViewById(R.id.Entrer);
btn.setOnClickListener(this);
Most likely, findViewById above is returning null. btn.setOnClickListener is crashing on a null pointer exception. (Because btn is null).
It is extremely likely, since you are using the default fragment structure created by the Eclipse solution, that the Button is really in the fragment layout file (fragment_main.xml) and not in activity_main.xml. (Hence, the button is not in the Activity view, it's in the fragment view).
If that's the case, then move the above two lines into the onCreateView method of the PlaceholderFragment.
Related
I'm new to this and i'm doing an app for a university project and I wanted to put a VideoView in my app, so I watched this video ("https://www.youtube.com/watch?v=SrPHLj_q_OQ&t=421s") and did it and worked. But then I add to copy the code from content_main.xml to a fragment and it stopped working and giving an error on the "android:onClick" on the Button. And when I press CTRL+F1 to inspect it says this:
"Corresponding method handler'public void videoplay(android.view.View)' not found
Inspection info:The onClick attribute value should be the name of a method in this View's context to invoke when the view is clicked.This name must correspond to a public method that takes exactly one parameter of type View.
Must be a string value, using '\;' to escape characters such as '\n' or '\uxxxx' for a unicode character.
Issue id:OnClick "
Heres my xml:
<?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="16dp"
android:paddingLeft="16dp"
android:paddingRight="16dp"
android:paddingTop="16dp"
android:background="#003e6f"
android:orientation="vertical"
tools:context=".InicioFragment">
<VideoView
android:id="#+id/videoView"
android:layout_width="match_parent"
android:layout_gravity="center_horizontal"
android:layout_height="197dp" />
<Button
android:id="#+id/button2"
style="#style/Widget.AppCompat.Button.Borderless"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal"
android:background="#FF6600"
android:text="Play"
android:onClick="videoplay"
android:textColor="#ffffff" />
<ImageView
android:id="#+id/imagem2"
android:layout_width="match_parent"
android:layout_height="360dp"
android:layout_alignParentBottom="true"
android:adjustViewBounds="false"
android:background="#drawable/tech3" />
</LinearLayout>
Heres my java:
package intro.android.migueloliveiraapp;
import android.net.Uri;
import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.view.View;
import android.support.design.widget.NavigationView;
import android.support.v4.view.GravityCompat;
import android.support.v4.widget.DrawerLayout;
import android.support.v7.app.ActionBarDrawerToggle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.Button;
import android.widget.Toast;
import android.widget.VideoView;
public class MainActivity extends AppCompatActivity
implements NavigationView.OnNavigationItemSelectedListener {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
clk = (Button) findViewById(R.id.button2);
videov = (VideoView) findViewById(R.id.videoView);
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
drawer.addDrawerListener(toggle);
toggle.syncState();
NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view);
navigationView.setNavigationItemSelectedListener(this);
//Carregar o layout do fragent incial "InicioFragment"
InicioFragment inicioFragment = new InicioFragment();
FragmentManager manager = getSupportFragmentManager();
manager.beginTransaction()
.replace(R.id.relative_layout_para_o_fragment, inicioFragment, inicioFragment.getTag())
.commit();
}
#Override
public boolean onNavigationItemSelected(MenuItem item) {
// Handle navigation view item clicks here.
int id = item.getItemId();
if (id == R.id.nav_oliveira) {
Quem_Oliveira quem_oliveiraFragment = new Quem_Oliveira();
FragmentManager manager = getSupportFragmentManager();
manager.beginTransaction()
.replace(R.id.relative_layout_para_o_fragment,
quem_oliveiraFragment, quem_oliveiraFragment.getTag())
.commit();
Toast.makeText(this, "Oliveira", Toast.LENGTH_SHORT).show();
} else if (id == R.id.nav_profissao) {
Profissao profissaoFragment = new Profissao();
FragmentManager manager = getSupportFragmentManager();
manager.beginTransaction()
.replace(R.id.relative_layout_para_o_fragment,
profissaoFragment, profissaoFragment.getTag())
.commit();
Toast.makeText(this, "Profissão", Toast.LENGTH_SHORT).show();
} else if (id == R.id.nav_feitos) {
Principais_feitos principais_feitosFragment = new Principais_feitos();
FragmentManager manager = getSupportFragmentManager();
manager.beginTransaction()
.replace(R.id.relative_layout_para_o_fragment,
principais_feitosFragment, principais_feitosFragment.getTag())
.commit();
Toast.makeText(this, "Principais Feitos", Toast.LENGTH_SHORT).show();
} else if (id == R.id.nav_academicas) {
Habilitacoes_Academicas habilitacoes_academicasFragment = new Habilitacoes_Academicas();
FragmentManager manager = getSupportFragmentManager();
manager.beginTransaction()
.replace(R.id.relative_layout_para_o_fragment,
habilitacoes_academicasFragment, habilitacoes_academicasFragment.getTag())
.commit();
Toast.makeText(this, "Habilitações Académicas", Toast.LENGTH_SHORT).show();
} else if (id == R.id.nav_galeria) {
Galeria galeriaFragment = new Galeria();
FragmentManager manager = getSupportFragmentManager();
manager.beginTransaction()
.replace(R.id.relative_layout_para_o_fragment,
galeriaFragment, galeriaFragment.getTag())
.commit();
Toast.makeText(this, "Galeria", Toast.LENGTH_SHORT).show();
} else if (id == R.id.nav_contactos) {
Contactos contactosFragment = new Contactos();
FragmentManager manager = getSupportFragmentManager();
manager.beginTransaction()
.replace(R.id.relative_layout_para_o_fragment,
contactosFragment, contactosFragment.getTag())
.commit();
Toast.makeText(this, "Contactos", Toast.LENGTH_SHORT).show();
}
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
drawer.closeDrawer(GravityCompat.START);
return true;
}
//video view
Button clk;
VideoView videov;
public void videoplay(View v){
String videopath = "android.resource://intro.android.migueloliveiraapp/" + R.raw.oliveira;
Uri uri = Uri.parse(videopath);
videov.setVideoURI(uri);
videov.start();
}
}
Heres my InicioFragment java:
package intro.android.migueloliveiraapp;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
/**
* A simple {#link Fragment} subclass.
*/
public class InicioFragment extends Fragment {
public InicioFragment() {
// Required empty public constructor
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
return inflater.inflate(R.layout.fragment_inicio, container, false);
}
}
heres my updated InicioFragment.java:
package intro.android.migueloliveiraapp;
import android.os.Bundle;
import android.support.design.widget.NavigationView;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.net.Uri;
import android.widget.Button;
import android.widget.VideoView;
/**
* A simple {#link Fragment} subclass.
*/
public class InicioFragment extends Fragment {
public InicioFragment() {
// Required empty public constructor
}
#Override
public View onCreateView (LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
return inflater.inflate(R.layout.fragment_inicio, container, false);
}
#Override
public void onViewCreated(View view, Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
clk = (Button) view.findViewById(R.id.button);
videov = (VideoView) view.findViewById(R.id.videoView);
// bind the views here.
Button button2 = view.findViewById(R.id.button);
button2.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
// do something here.
}
});
}
Button clk;
VideoView videov;
public void videoplay(View v){
String videopath = "android.resource://intro.android.migueloliveiraapp/" + R.raw.oliveira;
Uri uri = Uri.parse(videopath);
videov.setVideoURI(uri);
videov.start();
}
}
You can use this for click.
Button mPlayVideo;
//In oncreate
mPlayVideo = findViewById(R.id.button2);
mPlayVideo.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Toast.makeText(MainActivity.this, "Clicked", Toast.LENGTH_SHORT).show();
}
});
In your xml your tools:context=".InicioFragment refers to your fragment and not your activity.
Your method is found inside the activity and not the fragment class and this is why are getting this error.
You can check Call an activity method from a fragment
But I can recommend using the onClick attribute inside your activities and inside fragment use normal click listener:
View view = findViewById(R.id.viewId);
view .setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
//do something
}
});
This is because you created videoplay() method inside your MainActivity.java . You should put your videoplay() method into the InicioFragment.java as it is the corresponding file for the xml layout you have mentioned above.
Initialize your variables like bellow inside your onCreateView method on InicioFragment
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View view = inflater.inflate(R.layout.fragment_inicio, container, false);
Button btn1 = view.findViewById(R.id.button_id);
.....
.....
return view;
}
public void videoplay(View v){
.........
.....
}
The following error:
"Corresponding method handler'public void videoplay(android.view.View)' not found
Inspection info:The onClick attribute value should be the name of a method in this View's context to invoke when the view is clicked.This name must correspond to a public method that takes exactly one parameter of type View.
Must be a string value, using '\;' to escape characters such as '\n' or '\uxxxx' for a unicode character.
Issue id:OnClick "
means that you forget to add the corresponding method in your Activity class when using android:onClick="videoplay" attribute. So, you need to add the following method to your activity:
public void videoplay(View v){
// do something here.
}
The most important part is, android:onClick tag is only working when you're using it inside the content layout of Activity.. So, android:onClick doesn't work when you're using it inside the fragment layout. You need to use the onClickListener instead.
You need to bind the view and add the onClickListener with something like this:
public class InicioFragment extends Fragment {
public InicioFragment() {}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
return inflater.inflate(R.layout.fragment_inicio, container, false);
}
#Override
public void onViewCreated(View view, Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
// bind the views here.
Button button2 = view.findViewById(R.id.button2);
button2.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
// do something here.
}
});
}
}
Pay attention on your xml file that this file's context is your InicioFragment (tools:context=".InicioFragment" )
Therefore, videoplay(View v) should be inside your InicioFragment class.
That's the reason why is not found. It won't search on your MainActivity.
public class InicioFragment extends Fragment {
public InicioFragment() {
// Required empty public constructor
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View view = inflater.inflate(R.layout.testclassfragment, container, false);
Button clk = (Button) view.findViewById(R.id.button);
VideoView videov = (VideoView) view.findViewById(R.id.videoView);
return view;
}
public void videoplay(View v){
String videopath = "android.resource://intro.android.migueloliveiraapp/" + R.raw.oliveira;
Uri uri = Uri.parse(videopath);
videov.setVideoURI(uri);
videov.start();
}
}
Since you also have a variable for your button another option is to do:
clk.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Log.d("TESTING", "Clicked");
}
});
I am making a simple app in which on home page, a button is placed. When the button is clicked, it must display a new page (xml in layout). How to do that ..
My app contains in src directory, There are two java files.
1. Activity2
2. Main_activity
and two xml files in layout:
1. fragment_main.xml
2. Activity.xml
I want that when i click "Technical button", it should display Activity.xml page from layout..
My codes:
Main_Activity.java
package com.example.vit;
import java.util.Locale;
import android.util.Log;
import android.support.v7.app.ActionBarActivity;
import android.support.v7.app.ActionBar;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentTransaction;
import android.support.v4.app.FragmentPagerAdapter;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.support.v4.view.ViewPager;
import android.view.Gravity;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
public class MainActivity extends ActionBarActivity implements
ActionBar.TabListener {
/**
* The {#link android.support.v4.view.PagerAdapter} that will provide
* fragments for each of the sections. We use a {#link FragmentPagerAdapter}
* derivative, which will keep every loaded fragment in memory. If this
* becomes too memory intensive, it may be best to switch to a
* {#link android.support.v4.app.FragmentStatePagerAdapter}.
*/
SectionsPagerAdapter mSectionsPagerAdapter;
/**
* The {#link ViewPager} that will host the section contents.
*/
ViewPager mViewPager;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Set up the action bar.
final ActionBar actionBar = getSupportActionBar();
actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
// Create the adapter that will return a fragment for each of the three
// primary sections of the activity.
mSectionsPagerAdapter = new SectionsPagerAdapter(
getSupportFragmentManager());
// Set up the ViewPager with the sections adapter.
mViewPager = (ViewPager) findViewById(R.id.pager);
mViewPager.setAdapter(mSectionsPagerAdapter);
// When swiping between different sections, select the corresponding
// tab. We can also use ActionBar.Tab#select() to do this if we have
// a reference to the Tab.
mViewPager
.setOnPageChangeListener(new ViewPager.SimpleOnPageChangeListener() {
#Override
public void onPageSelected(int position) {
actionBar.setSelectedNavigationItem(position);
}
});
// For each of the sections in the app, add a tab to the action bar.
for (int i = 0; i < mSectionsPagerAdapter.getCount(); i++) {
// Create a tab with text corresponding to the page title defined by
// the adapter. Also specify this Activity object, which implements
// the TabListener interface, as the callback (listener) for when
// this tab is selected.
actionBar.addTab(actionBar.newTab()
.setText(mSectionsPagerAdapter.getPageTitle(i))
.setTabListener(this));
}
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
#Override
public void onTabSelected(ActionBar.Tab tab,
FragmentTransaction fragmentTransaction) {
// When the given tab is selected, switch to the corresponding page in
// the ViewPager.
mViewPager.setCurrentItem(tab.getPosition());
}
#Override
public void onTabUnselected(ActionBar.Tab tab,
FragmentTransaction fragmentTransaction) {
}
#Override
public void onTabReselected(ActionBar.Tab tab,
FragmentTransaction fragmentTransaction) {
}
/**
* A {#link FragmentPagerAdapter} that returns a fragment corresponding to
* one of the sections/tabs/pages.
*/
public class SectionsPagerAdapter extends FragmentPagerAdapter {
public SectionsPagerAdapter(FragmentManager fm) {
super(fm);
}
#Override
public Fragment getItem(int position) {
// getItem is called to instantiate the fragment for the given page.
// Return a PlaceholderFragment (defined as a static inner class
// below).
return PlaceholderFragment.newInstance(position + 1);
}
#Override
public int getCount() {
// Show 3 total pages.
return 3;
}
#Override
public CharSequence getPageTitle(int position) {
Locale l = Locale.getDefault();
switch (position) {
case 0:
return getString(R.string.title_section1).toUpperCase(l);
case 1:
return getString(R.string.title_section2).toUpperCase(l);
case 2:
return getString(R.string.title_section3).toUpperCase(l);
}
return null;
}
}
/**
* A placeholder fragment containing a simple view.
*/
public static class PlaceholderFragment extends Fragment {
/**
* The fragment argument representing the section number for this
* fragment.
*/
private static final String ARG_SECTION_NUMBER = "section_number";
/**
* Returns a new instance of this fragment for the given section number.
*/
public static PlaceholderFragment newInstance(int sectionNumber) {
PlaceholderFragment fragment = new PlaceholderFragment();
Bundle args = new Bundle();
args.putInt(ARG_SECTION_NUMBER, sectionNumber);
fragment.setArguments(args);
return fragment;
}
public PlaceholderFragment() {
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_main, container,
false);
return rootView;
}
}
public void onClick(View v)
{
Intent intent = new Intent (v.getContext(),Activity.class);
startActivityForResult (intent,0);
}
}
2.Activity2.java
package com.example.vit;
import android.app.Activity;
public class Activity2 extends Activity
public void onCreate(Bundle, savedInstanceState)
{
{
super.onCreate(savedInstanceState);
setContentView(R.layout.Activity);
}
}
3. fragment_main.xml
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:paddingBottom="#dimen/activity_vertical_margin"
android:paddingLeft="#dimen/activity_horizontal_margin"
android:paddingRight="#dimen/activity_horizontal_margin"
android:paddingTop="#dimen/activity_vertical_margin"
tools:context="com.example.vit.MainActivity$PlaceholderFragment" >
<TextView
android:id="#+id/section_label"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
<Button
android:id="#+id/button1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="31dp"
android:onClick="doSomething"
android:text="Technical" />
<Button
android:id="#+id/button2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="50dp"
android:text="Non Technical" />
</LinearLayout>
Activity.xml
<TextView
android:id="#+id/section_label"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
<TextView
android:id="#+id/textView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Your request is being processed"
android:textAppearance="?android:attr/textAppearanceLarge" />
Intent intent = new Intent(this, ActivityTwo.class);
this.startActivity ( intent );
Note : #Don already provided a correct answer, but (sorry) lack of information. Accept his answer, i only help to add some informations (which is quite long if i put in comment)
In Android, a page/screen in your apps refer to the subclass of Activity. An Activity always have a xml layout.
So, if you want to change from one layout (or screen/page) to others, you should change the Activity, with the help of Intent class. This will automatically change the layout (as your question refer) because an Activity has a layout.
No offense, but i suggest you to search some videos/books/tutorials. I suggest Commonsware's book which is free (the old version, but still the best book in my opinion) :
http://commonsware.com/Android/4-2-free
all is going right but u have to include the following code
Intent intent = new Intent(this, ActivityTwo.class);
this.startActivity ( intent );
I keep getting errors in code below, specifically the two pieces surrounded by asterisks (R.id.action_settings and fragment_display_message,)
package com.example.completelypointlessapp;
import android.app.Fragment;
import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.view.LayoutInflater;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
public class DisplayMessageActivity extends ActionBarActivity {
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Get the message from the intent
Intent intent = getIntent();
String message = intent.getStringExtra(MainActivity.EXTRA_MESSAGE);
// Create the text view
TextView textView = new TextView(this);
textView.setTextSize(40);
textView.setText(message);
// Set the text view as the activity layout
setContentView(textView);
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
if (id == **R.id.action_settings**) {
return true;
}
return super.onOptionsItemSelected(item);
}
/**
* A placeholder fragment containing a simple view.
*/
public static class PlaceholderFragment extends Fragment {
public PlaceholderFragment() { }
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.**fragment_display_message,**
container, false);
return rootView;
}
}
}
The errors state:"fragment_display_message cannot be resolved or is not a field" and "action_settings cannot be resolved or is not a field"
Can anyone help resolve this?
(Apology for certain incorrect formatting, I am new to this site)
View rootView = inflater.inflate(R.layout.fragment_display_message,
container, false);
Do you have fragment_display_message.xml layout file ?
if (id == R.id.action_settings)
Do you have the custom menu file for ActionBar ?
Example -
<menu xmlns:android="http://schemas.android.com/apk/res/android" >
<item
android:id="#+id/action_settings"
android:title="Settings"
android:showAsAction="never"
>
</item>
</menu>
If answer to both is NO, then error is obvious.
Closed. This question needs debugging details. It is not currently accepting answers.
Edit the question to include desired behavior, a specific problem or error, and the shortest code necessary to reproduce the problem. This will help others answer the question.
Closed 8 years ago.
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I just starting learning to develop an android app and for that i followed google's basic tutorial.
In the tutorial there is simply a textbox and a button. On pressing the button it takes the text from the textbox and displays it in another activity. But somehow the button isn't working for me.
Here is the code for the fragment_main.xml, MainActivity.java and DisplayMessageActivity.java. I just want to know if i am doing something wrong or if i am missing something.
fragmant_main.xml:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="horizontal">
<EditText android:id="#+id/edit_message"
android:layout_weight="1"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:hint="#string/edit_message" />
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#string/button_send"
onClick="sendMessage" />
</LinearLayout>
MainActivity.java:
package com.example.first;
import android.content.Intent;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v7.app.ActionBarActivity;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.EditText;
public class MainActivity extends ActionBarActivity {
public final static String EXTRA_MESSAGE = "com.example.myfirstapp.MESSAGE";
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
if (savedInstanceState == null) {
getSupportFragmentManager().beginTransaction()
.add(R.id.container, new PlaceholderFragment()).commit();
}
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
/**
* A placeholder fragment containing a simple view.
*/
public static class PlaceholderFragment extends Fragment {
public PlaceholderFragment() {
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_main, container,
false);
return rootView;
}
}
/** Called when the user clicks the Send button */
public void sendMessage(View view) {
Intent intent = new Intent(this, DisplayMessageActivity.class);
EditText editText = (EditText) findViewById(R.id.edit_message);
String message = editText.getText().toString();
intent.putExtra(EXTRA_MESSAGE, message);
startActivity(intent);
}
}
DisplayMessageActivity.java
package com.example.first;
import android.content.Intent;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v7.app.ActionBarActivity;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
public class DisplayMessageActivity extends ActionBarActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Get the message from the intent
Intent intent = getIntent();
String message = intent.getStringExtra(MainActivity.EXTRA_MESSAGE);
// Create the text view
TextView textView = new TextView(this);
textView.setTextSize(40);
textView.setText(message);
// Set the text view as the activity layout
setContentView(textView);
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.display_message, menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
/**
* A placeholder fragment containing a simple view.
*/
public static class PlaceholderFragment extends Fragment {
public PlaceholderFragment() {
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_display_message,
container, false);
return rootView;
}
}
}
EDIT **
In your fragment_main.xml file the the last line of your Button tag should be : android:onClick="sendMessage" instead of onClick="sendMessage"
I'm trying to build an text view that goes to onClick but its not working they told me to add this code I did it but I'm having a lot of errors in it.
this is my MainActivity.java
package imamalsajadsayings.android.com;
import android.app.Activity;
import android.os.Bundle;
import android.view.Menu;
import android.view.View;
import android.widget.TextView;
public class MainActivity extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
public void runNextTask(){
final View addView = getLayoutInflater().inflate(R.layout.addnewtracker, null);
final TrackerInfo newInfo = new TrackerInfo();
//set up for model selection
TextView modelTextview = (TextView)addView.findViewById(R.id.state1);
modelTextview.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
}
});
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
}
and is my textview
<TextView
android:id="#+id/state1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#string/Tracker_model"
android:clickable="true"
note : I don't have addnewtracker created
errors :
Description Resource Path Location Type
TrackerInfo cannot be resolved to a type MainActivity.java /ImamAlsajadsayings/src/imamalsajadsayings/android/com line 20 Java Problem
addnewtracker cannot be resolved or is not a field MainActivity.java /ImamAlsajadsayings/src/imamalsajadsayings/android/com line 19 Java Problem
The method setOnClickListener(View.OnClickListener) in the type View is not applicable for the arguments (new OnClickListener(){}) MainActivity.java /ImamAlsajadsayings/src/imamalsajadsayings/android/com line 23 Java Problem
TrackerInfo cannot be resolved to a type MainActivity.java /ImamAlsajadsayings/src/imamalsajadsayings/android/com line 20 Java Problem
The method onClick(View) of type new OnClickListener(){} must override or implement a supertype method MainActivity.java /ImamAlsajadsayings/src/imamalsajadsayings/android/com line 25 Java Problem
OnClickListener cannot be resolved to a type MainActivity.java /ImamAlsajadsayings/src/imamalsajadsayings/android/com line 23 Java Problem
add to activity:
public void modelTextViewClick(View v) {
//do something on click
}
and to layout:
<TextView android:id="#+id/state1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#string/Tracker_model"
android:clickable="true"
android:onClick="modelTextViewClick"/>
and remove your on click listener.
Change below code to your XML file
<TextView android:id="#+id/state1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#string/Tracker_model"
android:clickable="true"
android:onClick="runNextTask"/>
and just modify your java file as follow.
public void runNextTask(View v){
final View addView = getLayoutInflater().inflate(R.layout.addnewtracker, null);
final TrackerInfo newInfo = new TrackerInfo();
//set up for model selection
TextView modelTextview = (TextView)addView.findViewById(R.id.state1);
modelTextview.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
}
});
you need to import this package to avoid this error
missing this -> import android.view.View.OnClickListener;
Use below piece of code.
package imamalsajadsayings.android.com;
import android.app.Activity;
import android.os.Bundle;
import android.view.Menu;
import android.view.View;
import android.widget.TextView;
public class MainActivity extends Activity {
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
public void runNextTask(){
final View addView = getLayoutInflater().inflate(R.layout.addnewtracker, null);
final TrackerInfo newInfo = new TrackerInfo();
//set up for model selection
TextView modelTextview = (TextView)addView.findViewById(R.id.state1);
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
public void modelTextViewClick(View view)
{
// here view reference is your text view reference.
// put your on click handler code.
}
}
difference between this code and your code is onclick handler. In xml you have already defined a on click handler which you have to use in activity code. Other way set onclick listener handler foe your widget. Your doing both but either one of them is allowed not both for any widget in android.
You haven't call runNextTask from ur onCreate()
u r inflating a layout but didn't add that layout in any layout of ur activity_main layout using addView method
thats why it didn't work
it should be
package imamalsajadsayings.android.com;
import android.app.Activity;
import android.os.Bundle;
import android.view.Menu;
import android.view.View;
import android.widget.TextView;
import android.view.View.OnClickListener;
public class MainActivity extends Activity {
private LayoutInflater inflater;
private LinearLayout someLayout;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
someLayout = (LinearLayout) findViewById(R.id.some_layout); //layout present in activity_main
inflater = (LayoutInflater)getSystemService(LAYOUT_INFLATER_SERVICE);
runNextTask();
}
public void runNextTask(){
LinearLayout mInflatedLayout = (LinearLayout) inflater.inflate(R.layout.addnewtracker, null);
final TrackerInfo newInfo = new TrackerInfo();
//set up for model selection
TextView modelTextview = (TextView)mInflatedLayout.findViewById(R.id.state1);
someLayout.addView(mInflatedLayout);
modelTextview.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
}
});
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
}
Assuming u r using LinearLayout in ur activity_main layout