监听EditText

0、得到焦点的时候，作一些处理

public class AbcActivity extends Activity implements OnFocusChangeListener{　　

@Override
    public void onFocusChange(View v, boolean hasFocus) {
        switch (v.getId()) {
        case R.id.edtKeys:
            setLayoutVisible(0);
            break;

        default:
            break;
        }
    }

}

1、点击文本框，输入值后，显示一个X的清空的按钮

2、点击清空按钮后，EditText清空，并且隐一个X的清空的按钮

edtKeys.addTextChangedListener(new TextWatcher() {

            @Override
            public void onTextChanged(CharSequence s, int start, int before,
                    int count) {
                if(s.toString().equals("")){
                    btn_delSearchKey.setVisibility(View.GONE);
                }else{
                    btn_delSearchKey.setVisibility(View.VISIBLE);
                }
            }

            @Override
            public void beforeTextChanged(CharSequence s, int start, int count,
                    int after) {

            }

            @Override
            public void afterTextChanged(Editable s) {

            }
        });
        edtKeys.setOnFocusChangeListener(this);