将值设置为静态变量将返回错误

亚当

我基本上试图将mRecyclerView的当前状态保存到一个静态的Parcelable变量中,以确保其安全onPause并将其恢复到mRcyclerView onResume。

这是我的静态变量的类:

public class MySavedState {
private static MySavedState ourInstance = new MySavedState();

private Parcelable state;

static MySavedState getInstance() {
    if(ourInstance == null){
        ourInstance = new MySavedState();
    }
    return ourInstance;
}

private MySavedState() {
}

public Parcelable getState() {
    return state;
}

public void setState(Parcelable state) {
    this.state = state;
}

}

这是我尝试设置值的行:

@Override
public void onPause() {
    super.onPause();

    Parcelable newState = mRecyclerView.onSaveInstanceState();
    state.setState(newState);


}

和错误消息:

java.lang.RuntimeException: Unable to pause activity {com.gunaya.tasmaew/com.gunaya.tasmaew.Controller.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void com.gunaya.tasmaew.Model.MySavedState.setState(android.os.Parcelable)' on a null object reference
                  at android.app.ActivityThread.performPauseActivity(ActivityThread.java:3745)
                  at android.app.ActivityThread.performPauseActivity(ActivityThread.java:3704)
                  at android.app.ActivityThread.handlePauseActivity(ActivityThread.java:3679)
                  at android.app.ActivityThread.access$1100(ActivityThread.java:177)
                  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1460)
                  at android.os.Handler.dispatchMessage(Handler.java:102)
                  at android.os.Looper.loop(Looper.java:145)
                  at android.app.ActivityThread.main(ActivityThread.java:5951)
                  at java.lang.reflect.Method.invoke(Native Method)
                  at java.lang.reflect.Method.invoke(Method.java:372)
                  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1388)
                  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1183)
               Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void com.gunaya.tasmaew.Model.MySavedState.setState(android.os.Parcelable)' on a null object reference
                  at com.gunaya.tasmaew.Controller.mListFragment.onPause(mListFragment.java:117)

作为一个额外的问题,我在调试器中始终显示此错误消息:

((Bundle)parce).mClassLoader = Cannot find local variable 'parce'

非常感谢您的宝贵时间。

可怕的袋熊

您的Singleton看起来还不错,但看来您没有找回它

MySavedState state = MySavedState.getInstance ();

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