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Programmatically changing background

I have this code that changes the background when you click a button however, I want to change the background every 10 seconds, and I want to switch between files img1.png, img2.png and img3.png and when the cycle is completed start all over again. Thanks in advance.
Here is the code:
In 'MainActivity.java'
package lucas.app_2001;
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.LinearLayout;
public class MainActivity extends Activity {
/** Called when the activity is first created. */
Button button;
LinearLayout mainLayout;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mainLayout=(LinearLayout)findViewById(R.id.myLayout);
button=(Button)findViewById(R.id.button1);
button.setOnClickListener(new View.OnClickListener() {
public void onClick(View arg0) {
mainLayout.setBackgroundResource(R.drawable.yellowgradient);
}
});
}
}
'MainActivity.xml':
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/myLayout"
android:layout_width="fill_parent"
android:layout_height="fill_parent" >
<Button
android:id="#+id/button1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true"
android:layout_marginLeft="64dp"
android:layout_marginTop="71dp"
android:text="Shout!" />
</LinearLayout>

You can do this way:
private Handler mHandler;
private Runnable mRunnable;
private int i = 0;
MainActivity.java:
public class MainActivity extends Activity {
/** Called when the activity is first created. */
Button button;
LinearLayout mainLayout;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mainLayout=(LinearLayout)findViewById(R.id.myLayout);
button=(Button)findViewById(R.id.button1);
button.setOnClickListener(new View.OnClickListener() {
public void onClick(View arg0) {
mainLayout.setBackgroundResource(R.drawable.yellowgradient);
}
});
mHandler = new Handler();
mRunnable = new Runnable(){
#Override
public void run() {
i++;
if(i==1){
mainLayout.setBackgroundResource(R.drawable.image_one);
}else if(i==2){
mainLayout.setBackgroundResource(R.drawable.image_two);
}else if(i==3){
mainLayout.setBackgroundResource(R.drawable.image_three);
i ==0;
}
mHandler.postDelayed(mRunnable , 10000);
}
};
mHandler .post(mRunnable);
}
}
on onStop():
if(mHandler!=null){
mHandler.removeCallbacks(mRunnable);
}
Done

Use a while loop to repeat.
To delay it for 10 seconds try something like this:
//wait 10 seconds
Button.postDelayed(new Runnable() {
#Override
public void run() {
Button.setClickable(true);
}
}, 10000);

Android Image Button

Android app, i wrote to test image button doesn't work. I have created a image button and implement an event listener for that button. What's wrong with this source code?
import android.view.View;
import android.view.View.OnClickListener;
import android.app.Activity;
import android.os.Bundle;
import android.widget.ImageButton;
import android.widget.Toast;
public class ImageButtonTestApp extends Activity {
ImageButton imageButton;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
}
public void eventListenerOnButton() {
imageButton = (ImageButton) findViewById(R.id.imageButton1);
imageButton.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View arg0) {
Toast.makeText(ImageButtonTestApp.this, "ImageButton is clicked!", Toast.LENGTH_SHORT).show();
}
});
}
}

u have written setOnClickListener in different method but u didnot call that method any where call that method in oncreate.
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
eventListenerOnButton();
}
try this one,

Try it
imageButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View arg0) {
Toast.makeText(ImageButtonTestApp.this, "ImageButton is clicked!", Toast.LENGTH_SHORT).show();
}
});

App Crashing on intent start with google maps

Java code for map activity
package com.schweigert.drinkingbuddy;
import android.app.Activity;
import android.os.Bundle;
public class BarMaps extends Activity {
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.barmaps);
}
}
XML Code
<?xml version="1.0" encoding="utf-8"?>
<fragment xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/map"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:name="com.google.android.gms.maps.MapFragment" >
</fragment>
Java code that starts intent
maps.setOnClickListener(new Button.OnClickListener(){
#Override
public void onClick(View v) {
Intent openMap = new Intent("com.schweigert.drinkingbuddy.BarMaps");
startActivity(openMap);
}
});
When i am running this code on my emulator i have set up on my computer it brings up the "This app wont run unless you update Google Play services. But when i run it on a physical device it just times out and says that the app has stopped working.Why am i getting such a difference in errors between my emulator and physical device?
Edit:
package com.schweigert.drinkingbuddy;
import android.os.Bundle;
import android.app.Activity;
import android.content.Intent;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.widget.EditText;
public class StartingPoint extends Activity {
double numDrinks;
int counter;
EditText standardDrinks;
Button bacIntent, maps, drinks;
TextView display;
Bundle testBundle;
#Override
protected void onCreate(Bundle testBundle) {
super.onCreate(testBundle);
setContentView(R.layout.activity_starting_point);
counter = 0;
bacIntent = (Button) findViewById(R.id.bacIntent);
maps = (Button) findViewById(R.id.Maps);
drinks = (Button) findViewById(R.id.drinks);
bacIntent.setOnClickListener(new Button.OnClickListener(){
#Override
public void onClick(View v){
try{
Intent openBac = new Intent("com.schweigert.drinkingbuddy.BloodAlcoholContent");
startActivity(openBac);
}
catch(Exception e)
{
display.setText("my d" + e);
}
}
});
maps.setOnClickListener(new Button.OnClickListener(){
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
try{
Intent openMap = new Intent("com.schweigert.drinkingbuddy.MainActivity");
startActivity(openMap);
}
catch(Exception e){
display.setText("my d"+ e);
}
}
});
drinks.setOnClickListener(new Button.OnClickListener(){
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
try{
Intent openDrinkMenu = new Intent("com.schweigert.drinkingbuddy.DrinkType");
startActivity(openDrinkMenu);
}
catch(Exception e){
display.setText("my d:" + e);
}
}
});
}
}

So i had a try catch that was interacting with a textview that didn't exist anymore and then i had my manifest set up incorrectly. Thanks for the help Shivan.

Android - Toast button not appearing

After reading about Android's Toast class, I had to try it out.
I added a button to my layout, followed the instructions on this page, and added an OnClickListener to my button that would call the toast.
The problem now is that when I debug the app, the button doesn't appear on the view.
Do I have something where it's not supposed to be? (Additional information available upon request)
Code:
activity_main.xml
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/relLayout"
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=".MainActivity" >
<Button
android:id="#+id/button1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true"
android:text="Button" />
</RelativeLayout>
MainActivity.java
package com.joseph.toasttest;
import com.joseph.toasttest.R;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;
import android.app.Activity;
import android.content.Context;
public class MainActivity extends Activity {
Context context = getApplicationContext();
CharSequence text = "Test";
int duration = Toast.LENGTH_SHORT;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button btnToast = (Button) findViewById(R.id.button1);
btnToast.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
toastMe(v);
}
});
}
private void toastMe(View v) {
Toast.makeText(context, text, duration).show();
}
}

try this :
btnToast.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
Toast msg = Toast.makeText(MainActivity.this, text, duration );
msg.show();

Just guessing here, but I'd start removing those paddings in your RelativeLayout. You may be running the app in a device in which values of
#dimen/activity_vertical_margin
and/or
#dimen/activity_horizontal_margin
are 'moving' your button out of the screen. You can also try aligning the button in the center of the view.-
<Button
android:id="#+id/button1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerInParent="true"
android:text="Button" />

You must create your context inside onCreate() method:
package com.joseph.toasttest;
import com.joseph.toasttest.R;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;
import android.app.Activity;
import android.content.Context;
public class MainActivity extends Activity {
Context context = getApplicationContext();
CharSequence text = "Test";
int duration = Toast.LENGTH_SHORT;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button btnToast = (Button) findViewById(R.id.button1);
btnToast.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
toastMe(v);
}
});
}
private void toastMe(View v) {
Toast.makeText(context, text, duration).show();
}
}

You can't use the application context for UI stuff, like creating dialogs, toasts or launching activities. Just use the activity as a context instead.
Different contexts in Android, and what they can and can't be used for.

I got it to work by removing the context and duration variables altogether and setting them manually inside my Toast method.
public class MainActivity extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button btnToast = (Button) findViewById(R.id.button1);
btnToast.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
toastMe(v);
}
});
}
private void toastMe(View v) {
Toast.makeText(getApplicationContext(), "Test", Toast.LENGTH_SHORT).show();
}
}

This should work:
package com.joseph.toasttest;
import com.joseph.toasttest.R;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;
import android.app.Activity;
import android.content.Context;
public class MainActivity extends Activity {
CharSequence text = "Test";
int duration = Toast.LENGTH_SHORT;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button btnToast = (Button) findViewById(R.id.button1);
btnToast.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
toastMe(this);
}
});
}
private void toastMe(Context context) {
Toast.makeText(context, text, duration).show();
}
}

button can not be resolved

This is my starting activity. I'm trying to get this button to work but it's been giving me this error.
Line 15 button can not be resolved.
package com.synamegames.giveaway;
import android.view.View.OnClickListener;
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
public class GiveawayActivity extends Activity {
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
final Button register = (Button) findViewById(R.id.register);
button.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
// Perform action on clicks
}
});
setContentView(R.layout.main);
}
}

Please try this..
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
final Button register = (Button) findViewById(R.id.register);
register.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
// Perform action on clicks
}
});
}

The problem is You have defined the Button instances as register in the line final Button register = (Button) findViewById(R.id.register); But you are setting onclick listener to the button instance which is not defined. You should have
register.setOnClickListener(new OnClickListener() {
instead of
button.setOnClickListener(new OnClickListener() {

U can use android:onClick from xml and pass a the view into the .java file
eg:
android:onClick="bactToList"
in java:
public void bactToList(View view){
}