protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);
setContentView(R.layout.first_layout);
Button button1 = (Button) findViewById(R.id.button_1);
button1.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
Toast.makeText(FirstActivity.this, "You clicked Button 1",
Toast.LENGTH_SHORT).show();
}
});
}
<Button
android:id="@+id/button_1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Button 1"
/>