public class MainActivity extends Activity implements OnClickListener{

	Boolean a = false;
	Boolean b = false;
	Boolean c = false;

	Button buttonA;
	Button buttonB;
	Button buttonC;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);

		buttonA = (Button)findViewById(R.id.button_a);
		buttonB = (Button)findViewById(R.id.button_b);
		buttonC = (Button)findViewById(R.id.button_c);

		buttonA.setOnClickListener(this);
		buttonB.setOnClickListener(this);
		buttonC.setOnClickListener(this);

	}
	@Override
	public void onClick(View v) {
		Button button;
		button = (Button)v;

		if(button == buttonA)	a = true;
		if(button == buttonB)	b = true;
		if(button == buttonC)	c = true;

		if(a && b && c)
			sendButton();
	}

	private void sendButton(){
		//３つのボタンが押された時にやりたい処理

		a = false;
		b = false;
		c = false;
	}
}