学步园

在看API Demo中的GestureBuilderActivity时候遇到了一个比较恶心的问题：

本来想看Add gesture这个Button的点击事件是如何写的，但是根据他的id没有能找到

<Button
            android:id="@+id/addButton"
            android:onClick="addGesture"

            android:layout_width="0dip"
            android:layout_height="wrap_content"
            android:layout_weight="1"

            android:enabled="false"
            android:text="@string/button_add" />

但是根据代码中函数的名字和断点调试发现走的就是下面的函数：

 @SuppressWarnings({"UnusedDeclaration"})
    public void addGesture(View v) {
        Intent intent = new Intent(this, CreateGestureActivity.class);
        startActivityForResult(intent, REQUEST_NEW_GESTURE);
    }

仔细一看原来定义这个Button的时候有一个属性android:onClick="addGesture"

However, instead of applying an OnClickListener to
the button in your activity, you can assign a method to your button in the XML layout, using the android:onClick attribute.
For example:

 <Button
     android:layout_height="wrap_content"
     android:layout_width="wrap_content"
     android:text="@string/self_destruct"
     android:onClick="selfDestruct" />

Now, when a user clicks the button, the Android system calls the activity's selfDestruct(View) method. In order for this to work, the method must be public and accept a View as
its only parameter. For example:

 public void selfDestruct(View view) {
     // Kabloey
 }

The View passed into the method is a reference to the widget
that was clicked.