• change of background color
import androidx.appcompat.app.AlertDialog;
import androidx.appcompat.app.AppCompatActivity;
import androidx.constraintlayout.widget.ConstraintLayout;
import android.content.DialogInterface;
import android.graphics.Color;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import java.util.Random;
public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button b1=(Button) findViewById(R.id.button);
b1.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
AlertDialog.Builder b=new AlertDialog.Builder(MainActivity.this);
b.setTitle("BackGround Color Changer");
b.setMessage("Are you sure you want to change the color");
b.setPositiveButton("yes", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialogInterface, int i) {
ConstraintLayout r=findViewById(R.id.cl);
Random gen=new Random();
r.setBackgroundColor(Color.rgb(gen.nextInt(256),gen.nextInt(100),gen.nextInt
(100)));
}
});
b.setNegativeButton("no", new DialogInterface.OnClickListener()
{
@Override
public void onClick(DialogInterface dialogInterface, int i) {
}
});
b.show();
}
});
}
}
• change of background image
import androidx.appcompat.app.AlertDialog;
import androidx.appcompat.app.AppCompatActivity;
import androidx.constraintlayout.widget.ConstraintLayout;
import androidx.core.content.ContextCompat;
import android.content.DialogInterface;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;
import java.util.Random;
public class MainActivity extends AppCompatActivity {
int [] back_images;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
ConstraintLayout r=findViewById(R.id.cl);
Button b1=(Button) findViewById(R.id.button);
b1.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
AlertDialog.Builder b=new AlertDialog.Builder(MainActivity.this);
b.setTitle("BackGround Image Changer");
b.setMessage("Are you sure you want to change background image?");
back_images=new
int[]{R.drawable.picture1,R.drawable.picture2,R.drawable.picture3,R.drawable.picture
4};
b.setPositiveButton("yes", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialogInterface, int i) {
int arrlength=back_images.length;
Random gen=new Random();
int ran_no=gen.nextInt(4);
r.setBackground(ContextCompat.getDrawable(getApplicationContext(),back_images[r
an_no]));
}
});
b.setNegativeButton("no", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialogInterface, int i) {
}
});
b.show();
}
});
}
}