@Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); Button button1 = (Button) findViewById(R.id.button1); button1.setOnClickListener(new View.OnClickListener() { @Override Button button2 = (Button) findViewById(R.id.button2); button2.setOnClickListener(new View.OnClickListener() { @Override Button button3 = (Button) findViewById(R.id.button3); button3.setOnClickListener(new View.OnClickListener() { @Override