删除和添加视图 NPE、蜂窝、android答案

【问题标题】：remove and add view NPE, honeycomb, android删除和添加视图 NPE、蜂窝、android
【发布时间】：2012-01-31 10:51:44
【问题描述】：

我有LinearLayout areaForGalleries 以编程方式填充Gallery 组件，一个接一个。每个画廊中的onItemClick 方法将其从areaForGalleries 中删除，并将其添加到RelativeLayout parentLayout，它是areaForGalleries 的父级。请参阅下面的代码。

LinearLayout areaForGalleries;
RelativeLayout parentLayout;

...
private void showGallery() {
final CustomGallery mGallery = new CustomGallery(mContext);

mGallery.setOnItemClickListener(new CustomAdapterView.OnItemClickListener() {
        public void onItemClick(CustomAdapterView<?> parent, View v, int position, long id) {
            areaForGalleries.removeView(mGallery);
            parentLayout.addView(mGallery);
        }
    });

CustomGallery 是我对 Android Gallery 组件的实现。我只改变了画廊向左的对齐方式——一行代码已经改变。代码在 Android 2.1 - 2.3.3 上完美运行，但在 Honeycomb 或 ICS 上尝试时会崩溃并出现以下错误：

01-31 10:31:49.596: E/AndroidRuntime(1536): FATAL EXCEPTION: main
01-31 10:31:49.596: E/AndroidRuntime(1536): java.lang.NullPointerException
01-31 10:31:49.596: E/AndroidRuntime(1536):     at android.view.GestureDetector.onTouchEvent(GestureDetector.java:587)
01-31 10:31:49.596: E/AndroidRuntime(1536):     at com.my.example.pullrefreshgallery.CustomGallery.onTouchEvent(CustomGallery.java:812)
01-31 10:31:49.596: E/AndroidRuntime(1536):     at android.view.View.dispatchTouchEvent(View.java:5486)
01-31 10:31:49.596: E/AndroidRuntime(1536):     at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:1953)
01-31 10:31:49.596: E/AndroidRuntime(1536):     at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1714)
01-31 10:31:49.596: E/AndroidRuntime(1536):     at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:1959)
01-31 10:31:49.596: E/AndroidRuntime(1536):     at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1728)
01-31 10:31:49.596: E/AndroidRuntime(1536):     at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:1959)
01-31 10:31:49.596: E/AndroidRuntime(1536):     at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1728)
01-31 10:31:49.596: E/AndroidRuntime(1536):     at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:1959)
01-31 10:31:49.596: E/AndroidRuntime(1536):     at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1728)
01-31 10:31:49.596: E/AndroidRuntime(1536):     at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:1959)
01-31 10:31:49.596: E/AndroidRuntime(1536):     at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1728)
01-31 10:31:49.596: E/AndroidRuntime(1536):     at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:1959)
01-31 10:31:49.596: E/AndroidRuntime(1536):     at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1728)
01-31 10:31:49.596: E/AndroidRuntime(1536):     at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:1959)
01-31 10:31:49.596: E/AndroidRuntime(1536):     at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1728)
01-31 10:31:49.596: E/AndroidRuntime(1536):     at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:1959)
01-31 10:31:49.596: E/AndroidRuntime(1536):     at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1728)
01-31 10:31:49.596: E/AndroidRuntime(1536):     at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:1959)
01-31 10:31:49.596: E/AndroidRuntime(1536):     at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1728)
01-31 10:31:49.596: E/AndroidRuntime(1536):     at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:1959)
01-31 10:31:49.596: E/AndroidRuntime(1536):     at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1728)
01-31 10:31:49.596: E/AndroidRuntime(1536):     at com.android.internal.policy.impl.PhoneWindow$DecorView.superDispatchTouchEvent(PhoneWindow.java:1892)
01-31 10:31:49.596: E/AndroidRuntime(1536):     at com.android.internal.policy.impl.PhoneWindow.superDispatchTouchEvent(PhoneWindow.java:1371)
01-31 10:31:49.596: E/AndroidRuntime(1536):     at android.app.Activity.dispatchTouchEvent(Activity.java:2364)
01-31 10:31:49.596: E/AndroidRuntime(1536):     at com.my.example.Home.dispatchTouchEvent(Home.java:883)
01-31 10:31:49.596: E/AndroidRuntime(1536):     at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchTouchEvent(PhoneWindow.java:1840)
01-31 10:31:49.596: E/AndroidRuntime(1536):     at android.view.View.dispatchPointerEvent(View.java:5662)
01-31 10:31:49.596: E/AndroidRuntime(1536):     at android.view.ViewRootImpl.deliverPointerEvent(ViewRootImpl.java:2863)
01-31 10:31:49.596: E/AndroidRuntime(1536):     at android.view.ViewRootImpl.handleMessage(ViewRootImpl.java:2442)
01-31 10:31:49.596: E/AndroidRuntime(1536):     at android.os.Handler.dispatchMessage(Handler.java:99)
01-31 10:31:49.596: E/AndroidRuntime(1536):     at android.os.Looper.loop(Looper.java:137)
01-31 10:31:49.596: E/AndroidRuntime(1536):     at android.app.ActivityThread.main(ActivityThread.java:4340)
01-31 10:31:49.596: E/AndroidRuntime(1536):     at java.lang.reflect.Method.invokeNative(Native Method)
01-31 10:31:49.596: E/AndroidRuntime(1536):     at java.lang.reflect.Method.invoke(Method.java:511)
01-31 10:31:49.596: E/AndroidRuntime(1536):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
01-31 10:31:49.596: E/AndroidRuntime(1536):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
01-31 10:31:49.596: E/AndroidRuntime(1536):     at dalvik.system.NativeStart.main(Native Method)

NullPointerException 指的是CustomGallery 方法，我完全没改：

@Override
public boolean onTouchEvent(MotionEvent event) {

    // Give everything to the gesture detector
    boolean retValue = mGestureDetector.onTouchEvent(event);

    int action = event.getAction();
    if (action == MotionEvent.ACTION_UP) {
        // Helper method for lifted finger
        onUp();
    } else if (action == MotionEvent.ACTION_CANCEL) {
        onCancel();
    }

    return retValue;

}

当我注释掉删除和添加mGallery 的行时，一切正常！有similar problem，但我没有使用片段。

任何想法有什么问题吗？谢谢！

【问题讨论】：

标签： android nullpointerexception android-3.0-honeycomb add android-gallery

【解决方案1】：

我现在不是您正在等待的答案，但我只是在原始画廊小部件上的 ICS 上遇到了同样的问题（未超载）。

经过一些测试，我终于使用了简单的方法：try...catch

@Override
public boolean onTouchEvent(MotionEvent event) {
    try {
        return super.onTouchEvent(event);
    } catch (Throwable t) {
        return true;
    }
}

Galley 和 onClickListener 仍然正常工作，所以对我没有副作用。

【讨论】：