I am having trouble linking my interface with my java.
package com.example.game;
import android.os.Bundle;
import android.R;
import android.app.Activity;
import android.view.Menu;
import android.widget.Button;
public class MainActivity extends Activity {
Button btn1 = (Button) findViewById(R.id.button1);
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main); <---- 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); <--- main
return true;
}
}
I am having trouble with the layout. I can link my buttons ect. but it always throws an error on the generated code? why does it do this? I did the suggested fixes and ran it, which resulted into a crash... I am new to java and android development. I am learning as I go. I do have other experience in visual basic and what not.
Suggested fixes:
change to activity_list_ item
and can not be resolved.
Your btn1 assignment is incorrect. When you're assigning it on initialization, there is no view, as the code is run prior to onCreate. Instead, it should look like this:
Button btn1;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main); <---- activity_main
btn1 = (Button) findViewById(R.id.button1);
}
Related
I am begginer in java and ArcGIS for android. I want to make simple app with MapView.
I have problem with declaration of MapView center and Zoom. I need to do it programmatically (application startup) in java file, not in xml file. I will try explain it on on simple example.
Problem is in mMapView.setMapOptions(options); I need to do in onCreate(), if I make Button with mMapView.setMapOptions(options); everything is OK. I searched solution in samples and on the internet, but I think, that I do not know how to ask on it.
Sorry for my english and thank you for your comments.
import android.app.Activity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import com.esri.android.map.MapOptions;
import com.esri.android.map.MapView;
public class MainActivity extends Activity {
MapView mMapView = null;
Button b1;
MapOptions options = new MapOptions(MapOptions.MapType.TOPO, 49.591241, 17.255503, 16);
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mMapView = (MapView) findViewById(R.id.map);
//mMapView.centerAndZoom(49.591241, 17.255503, 8);
btnClick();
mMapView.setMapOptions(options);
mMapView.setAllowRotationByPinch(true);
mMapView.setRotationAngle(25);
mMapView.enableWrapAround(true);
}
public void btnClick() {
b1 = (Button) findViewById(R.id.button);
b1.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View arg0) {
//mMapView.centerAndZoom(49.591241, 17.255503, 10);
mMapView.setMapOptions(options);
}
});
}
#Override
protected void onPause() {
super.onPause();
// Call MapView.pause to suspend map rendering while the activity is paused, which can save battery usage.
mMapView.pause();
}
#Override
protected void onResume() {
super.onResume();
// Call MapView.unpause to resume map rendering when the activity returns to the foreground.
mMapView.unpause();
}
#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);
}
}
You could remove the MapView declaration from your XML and create it inside the activity. Then just add the MapView to your layout.
XML (details omitted)
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout android:id="#+id/mapLayout"></LinearLayout>
MainActivity.java
#Override
protected void onCreate(Bundle savedInstanceState) {
MapView mapView = MapView(MainActivity.this, mapOpts);
// other logic/initializations
ViewGroup mapLayout = findViewById(R.id.mapLayout);
mapLayout.addView(mapView); // might have to specify index param if you need buttons
This is my solution by previous answer. Thanks zec!
import android.app.Activity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import com.esri.android.map.MapOptions;
import com.esri.android.map.MapView;
public class MainActivity extends Activity {
MapView mMapView;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
MapOptions options = new MapOptions(MapOptions.MapType.TOPO, 49.591241, 17.255503, 16);
mMapView = new MapView(MainActivity.this, options);
setContentView(mMapView);
}
#Override
protected void onPause() {
super.onPause();
// Call MapView.pause to suspend map rendering while the activity is paused, which can save battery usage.
mMapView.pause();
}
#Override
protected void onResume() {
super.onResume();
// Call MapView.unpause to resume map rendering when the activity returns to the foreground.
mMapView.unpause();
}
}
I'm really new in android and java, but im trying to make an android app.
Im trying to make something were you can just type in your name and then it should view it by a push on a button. Eclipse is giving me the "unreachable code" error. I was wondering if you guys could see what i was doing wrong. The error is given in the two rules with final in front of it. If i remove one of these rules it will just move the error to the other rule.
Thank you in advance,
Marek
package com.tutorial.helloworld2;
import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
public class MainActivity extends Activity {
#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;
final EditText nameField = (EditText) findViewById(R.id.nameField);
final TextView nameView = (TextView) findViewById(R.id.nameView);
Button button = (Button) findViewById(R.id.button);
button.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
nameView.setText("Hello " + nameField.getText());
}
});
}
}
Move return true to the end of method as the method execution will end on this statement and no code below will be executed.
it is due to return statement, return will return a true and exit the entire method you have currently written code in. you should write this in onCreate() like.
#Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
final EditText nameField = (EditText) findViewById(R.id.nameField);
final TextView nameView = (TextView) findViewById(R.id.nameView);
Button button = (Button) findViewById(R.id.button);
button.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
nameView.setText("Hello " + nameField.getText());
}
});
}
now you will get your desired result
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
My app force closes on the onClick (goForIt). I'm just trying to set a content View but it forces closes eatch time I press my button. And also is it possible to make an app with only 1 activity ?
Could somebody tell me why please:
package com.XanderApps.techquizz;
import android.app.Activity;
import android.os.Bundle;
import android.view.Menu;
import android.view.View;
import android.widget.CheckBox;
public class MainActivity extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
public void goForIt(View view) {
setContentView(R.layout.question_one);
}
public void onCheckboxClicked(View view) {
boolean checked = ((CheckBox) view).isChecked();
switch(view.getId()) {
case R.id.checkbox_meat:
if (checked)
setContentView(R.layout.choice_done);
break;
case R.id.checkbox_cheese:
if (checked)
System.exit(0);
break;
}
}
#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;
}
}
Without looking at your Logcat, my guess is that you are getting a 'NullPointerException' when you try to access your button.
Make sure you are 'instantiating' your button object using the findViewById syntax, before you are trying to use onClick().
As you haven't instantiated your goForIt inside onCreateView() of Activity. Thus it throws NPE(Null Pointer Exception).
Get your id of goForIt from your XML layout file.
Add
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
goForit=(Button)findViewById(R.id.goForItId);
}
And then add onClickListener on goForIt.
Maybe it sounds silly, but I am getting an error on Button keyword (where it should not be).
I am a newbie, and looked almost everywhere. And everyone says that
Button b = findViewById(R.id.button1);
is correct.
My code:
package com.example.myfirstappnew;
import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
public class MainActivity extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button b = findViewById(R.id.button1);
}
#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;
}
}
Here is the screenshot:
http://pbrd.co/ZEsSw7
From what I see, you have an error because findViewById returns View and not Button, and you need to cast it to Button.
You need to cast the Button to a Button:
Button b = (Button) findViewById(R.id.button1);
And add this import:
import android.widget.Button;
Next time, when you say you have an error please include it :)
findViewById returns View, you need to cast it into Button.
Button b = (Button) findViewById(R.id.button1);
Edit:
Click on the first link that show import import Button(android.widget.)
or simply press ctrl+shift+o
The code needs to import Button (as suggested in the top hint in the screenshot).
First you need to change
Button b = findViewById(R.id.button1);
to
Button b = (Button) findViewById(R.id.button1);
You also need to add
import java.widget.Button;
to your import statements at the top of your file. If you are using Eclipse, you should use it's "organize imports" feature (or whatever Eclipse calls it) to do this automagically for you.