Android带加减的edittext

看了网上这样自带加减的edittext写得好复杂，还有各种监听事件，我觉得没有必有。于是我自己写了一个。 我这个edittext仅仅限制整数，每次加减1.

public class TestEditTextActivity extends Activity implements OnClickListener {

	private TextView tv_subtract, tv_add;
	private EditText et_rate;
	// 存储全局变量的数字
	private int num;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		// TODO Auto-generated method stub
		super.onCreate(savedInstanceState);
		setContentView(R.layout.second);
		tv_subtract = (TextView) findViewById(R.id.subtract);
		tv_add = (TextView) findViewById(R.id.add);
		et_rate=(EditText)findViewById(R.id.transfer_year_rate);
		tv_subtract.setOnClickListener(this);
		tv_add.setOnClickListener(this);
	}

	@Override
	public void onClick(View v) {
		switch (v.getId()) {
		case R.id.subtract: {
			String numString = et_rate.getText().toString();
			num = Integer.valueOf(numString) - 1;
			et_rate.setText(String.valueOf(num));
		}
			break;
		case R.id.add: {
			String numString = et_rate.getText().toString();
			num = Integer.valueOf(numString) + 1;
			et_rate.setText(String.valueOf(num));
		}
			break;

		default:
			break;
		}
	}