我正在研究UI事件处理，发现了一些问题，但在Android Dev中没有找到解释：我有一个ImageView和一个TextView，每当我点击ImageView时，TextView会显示一条消息。但以下代码无法正常工作：
public class ShowSomething extends Activity {
private LinearLayout ll;
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
LinearLayout ll = (LinearLayout)findViewById(R.id.linearLayout);
final TextView textview = (TextView)findViewById(R.id.textview);
MyImageView image = new MyImageView(this, textview);
image.setImageResource(R.drawable.icon);
ll.addView(image, 48, 48);
}
}
还有MyImageView.java文件
public class MyImageView extends ImageView implements OnTouchListener{
private TextView textview;
public MyImageView(Context context,TextView textview) {
super(context);
this.textview = textview;
}
@Override
public boolean onTouch(View v, MotionEvent event) {
textview.setText("Event captured !");
return true;
}
}
main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/linearLayout"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical"
>
<TextView
android:id="@+id/textview"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Holder"
/>
</LinearLayout>
但是当我在MyImageView上附加一个OnTouchListener时，它确实起作用：
文件ShowSomething.java
public class ShowSomething extends Activity {
private LinearLayout ll;
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
LinearLayout ll = (LinearLayout)findViewById(R.id.linearLayout);
final TextView textview = (TextView)findViewById(R.id.textview);
MyImageView image = new MyImageView(this,textview);
image.setImageResource(R.drawable.icon);
image.setOnTouchListener(new OnTouchListener() {
@Override
public boolean onTouch(View v, MotionEvent event) {
textview.setText("Event captured!");
return false;
}
});
ll.addView(image, 48, 48);
}
}
并且将文件MyImageView.java
public class MyImageView extends ImageView {
private TextView textview;
public MyImageView(Context context,TextView textview) {
super(context);
this.textview = textview;
}
}
但是据我所知，这两种实现方式是相同的（都是实现事件监听器）- 我有什么误解吗？