i'm starting to learn how to make android application by following the tutorial on their developer page. I'm trying to make a new DisplayMessageActivity class.
this is the tutorial https://developer.android.com/training/basics/firstapp/starting-activity.html#CreateActivity
My DisplayMessageActivity.java file contains by default this:
package com.example.myfirstapp;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
public class DisplayMessageActivity extends ActionBarActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_display_message);
}
#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);
}
}
while on their website it sais it should contain this :
public class DisplayMessageActivity extends ActionBarActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_display_message);
if (savedInstanceState == null) {
getSupportFragmentManager().beginTransaction()
.add(R.id.container, new PlaceholderFragment()).commit();
}
}
#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;
}
}
}
I have updated my eclipse to the latest version of ADT plugin and i still get this. When I try to paste their code to my DisplayMessageActivity.java file i get these errors:
activity_display_message cannot be resolved or is not a field
The method add(int, Fragment) in the type FragmentTransaction is not
applicable for the arguments (int,
DisplayMessageActivity.PlaceholderFragment)
fragment_display_message cannot be resolved or is not a field
Both of your references in the code should be to R.layout.activity_display_message, although I do not get any errors there (make sure you followed all the steps in the tutorial). But I am following the same tutorial and am getting the same error with the add method and cannot figure out why.
Related
I am new at Android and I'm trying to turn this Activity into a Fragment but I do not know how to resolve the Errors.
When I change it to a Fragment I get a lot of red code setContentView, findViewById, and getMenuInflater. I understand that these are probably red as they are meant to be used for Activities but I'm not sure what they are meant to be changed to.
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.view.Menu;
import android.view.MenuItem;
public class LocationsFragment extends Fragment {
RecyclerView recyclerView;
RecyclerView.LayoutManager layoutManager;
RecyclerView.Adapter adapter;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_card_demo);
// Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
// setSupportActionBar(toolbar);
recyclerView =
(RecyclerView) findViewById(R.id.recycler_view);
layoutManager = new LinearLayoutManager(this);
recyclerView.setLayoutManager(layoutManager);
adapter = new RecyclerAdapter();
recyclerView.setAdapter(adapter);
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_card_demo, 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();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
}
setContentView()
There is no method like this in Fragments. Instead, you override onCreateView() and return some view from it. You can use the passed-in LayoutInflater to inflate the layout id you'd normally pass to setContentView(), and then return that.
findViewById()
Fragments do not have a findViewById() method. However, any time after onCreateView() returns, you can instead use getView().findViewById(). Inside onCreateView(), if you named your inflated view root you could call root.findViewById(). Prior to onCreateView(), there's no way to look up any views (since they haven't been inflated yet).
getMenuInflater()
Fragments use a different signature for onCreateOptionsMenu(). It looks like this:
#Override
public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
// ...
}
You can use the passed-in MenuInflater instead of calling getMenuInflater().
Put that all together, and this is what you'd have:
public class LocationsFragment extends Fragment {
RecyclerView recyclerView;
RecyclerView.LayoutManager layoutManager;
RecyclerView.Adapter adapter;
#Nullable
#Override
public View onCreateView(#NonNull LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
View root = inflater.inflate(R.layout.activity_card_demo, container, false);
recyclerView = (RecyclerView) root.findViewById(R.id.recycler_view);
layoutManager = new LinearLayoutManager(getContext());
recyclerView.setLayoutManager(layoutManager);
adapter = new RecyclerAdapter();
recyclerView.setAdapter(adapter);
return root;
}
#Override
public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
inflater.inflate(R.menu.menu_card_demo, menu);
}
#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();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
}
I am joining two activity through intent
package com.smartcodeone.newapp1;
import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
public class MainActivity extends ActionBarActivity {
public static final String STRING_VAR = "com.smartcodeone.newapp1.HELLO_WORLD";
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button btnMsg = (Button) findViewById(R.id.btnMsg);
btnMsg.setOnClickListener(new View.OnClickListener(){
//when user click's this function will be called
public void onClick(View v){
Intent intentvar = new Intent(getApplicationContext(),Main2Activity.class);
intentvar.putExtra(STRING_VAR,"Hello World"); //this is used to pass data to next intent
startActivity(intentvar);
}
});
}
private int findViewId(int btnMsg) {
return 0;
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.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();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
#Override
public android.support.v4.app.FragmentManager getSupportFragmentManager() {
return null;
}
}
It might have to do with Android Studio. Try cleaning your project and then rebuilding. If that doesn't work go to File -> Invalidate Caches/Restart ...
I get those issues sometimes as well. Let me know if that works. I tried your code and it works fine.
The issue seems to be that you defined a method named: findViewById(int button) that always return 0.
Use the Activity method instead of your own:
this.findViewById(int resourceId)
Good luck!
It seems you are implementing your own findviewbyid(). I don't know if you intend to do so.
Try removing
private int findviewbyid(int btnMsg) {
}
The ActionBarActivity's findviewbyid should resolve your button from your layout file.
It's the same code in the tutorial but when I tried the code. It gives me the above error.
package com.example.rishav_pc.fragments;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.Menu;
import android.view.MenuItem;
public class MainActivity extends AppCompatActivity implements TopSectionFragment.TopSectionListner {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
// This gets called by the top fragment when the user clicks the button
#Override
public void createMeme(String top, String bottom) {
BottomPictureFragment bottomFragment = (BottomPictureFragment) getSupportFragmentManager().findFragmentById(R.id.fragment2);
bottomFragment.setMemeText(top, bottom);
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.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();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
}
There is one more error
Error:Execution failed for task ':app:compileDebugJava'.
Compilation failed; see the compiler error output for details.
In your BottomPictureFragment change the import of the extended class Fragment to be import android.support.v4.app.Fragment; . It seems that by you it is something else. You should have something like this :
import android.support.v4.app.Fragment;
...
public class BottomPictureFragment extends Fragment { ... }
I am new to android studio and I am reading the tutorials on i-programmer located here (http://www.i-programmer.info/programming/android/5914-android-adventures-activity-and-ui.html?start=2)
The two objects in the environment are a button and a large text widget instanced
in android studio's xml designer.
The problem: A method for setting text referenced in the tutorial is showing this error message when I try to run the code: error: cannot find symbol method setText(String)
And this error shows up in the text editor: Cannot resolve method 'setText(java.lang.String)'
Provided Source Code:
package com.example.helloworld1.helloworld1;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
public class MainActivity extends ActionBarActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
#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);
}
public void onButtonClick(View v){
Button button=(Button) v;
v.setText("I've Been Clicked!"); // This is where the error happens
}
}
I think you meant to use button instead of v.
button.setText("I've Been Clicked!");
I created a Main activity, which sends me to an ActiviteResultats activity.
My goal is now just to show a message in this activity (Message who come from the main).
I followed the Starting Another Activity tutorial.
The problem is, when I start the ActiviteResultats activity, I have an error:
"no view found for id 0x7f080000 ........... for fragment PlaceholderFragment"
... and the app shuts down.
I don't know yet how to use fragments, and the tutorial says I don't have to use it for this example.
Where am I going wrong?
My code :
package com.example.surveyor;
import android.app.Activity;
import android.app.Fragment;
import android.os.Bundle;
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 ActiviteResultats extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_activite_resultats);
if (savedInstanceState == null) {
getFragmentManager().beginTransaction()
.add(R.id.container, new PlaceholderFragment()).commit();
}
String message = "TODO";
// 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.activite_resultats, 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_activite_resultats, container, false);
return rootView;
}
}
}
I had the same problem. Just remove the part:
if (savedInstanceState == null) {
getFragmentManager().beginTransaction()
.add(R.id.container, new PlaceholderFragment()).commit();
}
That solved it for me. Hope that helps!
A quick look over the tutorial shows that most of the Fragment code is removed in a later step. You could remove all the code related to the fragments, along with the bit about the options menu if you want to clear out all distractions. It's likely to solve your problem and isn't vital to that tutorial
What you need to do is to set up intent in your main activity, and then get it here so it goes like follows:
under Main_Activity.java
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.Main_Activity);
Intent i = new Intent(this,activiteResultats.class); // or getApplicationContext() <= for context
i.putExtras("TagOfMyMessage","MyMessageblablabla");
startActivity(i);
}
under ActivteResultats.java
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_activite_resultats);
Intent i = getIntent();
String message = i.getStringExtras(); // or something like it
// 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);
}
You just don't need to use fragments if you want a clear and easy tutorial i advice you to check this one : http://www.vogella.com/tutorials/AndroidIntent/article.html