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我在自定义视图中有两个辅助方法，它们由它们的片段调用：

public Bundle returnInstanceState() {
        Bundle state = new Bundle();
        state.putSerializable("colorData", colorData);
        return state;
}

public void loadInstanceState(Bundle savedInstanceState) {
    if(savedInstanceState.getSerializable("colorData") != null)
            colorData = (int[][]) savedInstanceState.getSerializable("colorData");
}

颜色数据的生命周期：

private int[][] colorData;

protected void onSizeChanged (int w, int h, int oldw, int oldh) 
{
    width = w;
    height = h;
    screen = new int[width*height];
    cellSize = 0;
    if(firstLoad && h!= 0 && w!=0)
    {

    if(nWidth>nHeight)
        colorData = new int[nWidth/(nHeight/170 - 1) + 1][170];
    else
            colorData = new int[nHeight/(nWidth/170 - 1) + 1][170];
        firstLoad = false;
    }
}

nWidth并且nHeight是代表原始分辨率的静态 int。

然而，一旦在一个蓝色的月亮上，我就会得到一个 ClassCastException。为什么？

从我的测试看来，你可以投到null虽然那int[][]实际上不是我的目标。 colorData是类型int[][]，据我所知，我从来没有在任何地方得到 NullPointerException，除了强制转换的行为，Serializable而且int[][]只是偶尔。

这是一个堆栈跟踪，尽管在这种情况下它没有多大用处：

java.lang.RuntimeException: Unable to start activity ComponentInfo{<MYPACKAGENAMEHERE>/<MYPACKAGENAMEHERE>.MusicVisualizerActivity}: java.lang.ClassCastException: [Ljava.lang.Object;
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1659)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1675)
    at android.app.ActivityThread.access$1500(ActivityThread.java:121)
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:943)
    at android.os.Handler.dispatchMessage(Handler.java:99)
    at android.os.Looper.loop(Looper.java:130)
    at android.app.ActivityThread.main(ActivityThread.java:3701)
    at java.lang.reflect.Method.invokeNative(Native Method)
    at java.lang.reflect.Method.invoke(Method.java:507)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:866)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:624)
    at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.ClassCastException: [Ljava.lang.Object;
    at <MYPACKAGENAMEHERE>.Visualization_Spectral$RenderView.loadInstanceState(Visualization_Spectral.java:95)
    at <MYPACKAGENAMEHERE>.Visualization_Spectral.onCreateView(Visualization_Spectral.java:46)
    at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:870)
    at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1080)
    at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1062)
    at android.support.v4.app.FragmentManagerImpl.dispatchActivityCreated(FragmentManager.java:1810)
    at android.support.v4.app.FragmentActivity.onStart(FragmentActivity.java:501)
    at android.app.Instrumentation.callActivityOnStart(Instrumentation.java:1129)
    at android.app.Activity.performStart(Activity.java:3791)
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1632)
    ... 11 more
java.lang.ClassCastException: [Ljava.lang.Object;
    at <MYPACKAGENAMEHERE>.Visualization_Spectral$RenderView.loadInstanceState(Visualization_Spectral.java:95)
    at <MYPACKAGENAMEHERE>.visualization.Visualization_Spectral.onCreateView(Visualization_Spectral.java:46)
    at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:870)
    at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1080)
    at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1062)
    at android.support.v4.app.FragmentManagerImpl.dispatchActivityCreated(FragmentManager.java:1810)
    at android.support.v4.app.FragmentActivity.onStart(FragmentActivity.java:501)
    at android.app.Instrumentation.callActivityOnStart(Instrumentation.java:1129)
    at android.app.Activity.performStart(Activity.java:3791)
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1632)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1675)
    at android.app.ActivityThread.access$1500(ActivityThread.java:121)
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:943)
    at android.os.Handler.dispatchMessage(Handler.java:99)
    at android.os.Looper.loop(Looper.java:130)
    at android.app.ActivityThread.main(ActivityThread.java:3701)
    at java.lang.reflect.Method.invokeNative(Native Method)
    at java.lang.reflect.Method.invoke(Method.java:507)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:866)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:624)
    at dalvik.system.NativeStart.main(Native Method)
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2 回答 2

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如果Serializable界面充满缺陷，应尽可能避免使用，尤其是在 Android 中。从您的代码的外观来看，您只是暂时将此对象传递给 aBundle以便可以重新创建 Activity 或其他组件，如果没有别的，序列化对象将为这种临时需求提供较差的性能。

如果onRetainNonConfigurationInstance()您getLastNonConfigurationInstance()在Activity. 如果您正在使用FragmentAPI，请同时查看该setRetainInstance()方法。

高温高压

于 2012-06-24T23:38:25.463 回答
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对我来说，这看起来很奇怪，因为默认情况下 Java（多维）数组是可序列化的（或者我错了吗？）。但似乎，至少在 Android 中，与此有所不同。

无论如何，您应该使用 Parcelable 通过。实现起来有点乏味，但比 Serializable 更快......这是一个操作方法：使用 Serializable 传递多维数组

于 2012-06-24T23:51:24.787 回答