获取错误：为viewPager适配器执行notifyDataSetChanged时出现“java.lang.IllegalStateException：Activity已被销毁”

Question

我从onActivityResult（...）方法中的活动类调用viewDatar适配器的notifyDataSetChanged（）。我面临“致命异常：java.lang.IllegalStateException：Activity已被销毁”错误仅在某些设备中出现。下面是堆栈跟踪。

Fatal Exception: java.lang.IllegalStateException: Activity has been destroyed
   at android.support.v4.app.FragmentManagerImpl.enqueueAction(FragmentManager.java:1515)
   at android.support.v4.app.BackStackRecord.commitInternal(BackStackRecord.java:638)
   at android.support.v4.app.BackStackRecord.commitAllowingStateLoss(BackStackRecord.java:621)
   at android.support.v4.app.FragmentPagerAdapter.finishUpdate(FragmentPagerAdapter.java:139)
   at android.support.v4.view.ViewPager.dataSetChanged(ViewPager.java:1003)
   at android.support.v4.view.ViewPager$PagerObserver.onChanged(ViewPager.java:2996)
   at android.support.v4.view.PagerAdapter.notifyDataSetChanged(PagerAdapter.java:279)
   at com.demo.activities.ActivityMain$1.run(ActivityMain.java:180)
   at android.os.Handler.handleCallback(Handler.java:751)
   at android.os.Handler.dispatchMessage(Handler.java:95)
   at android.os.Looper.loop(Looper.java:154)
   at android.app.ActivityThread.main(ActivityThread.java:6351)
   at java.lang.reflect.Method.invoke(Method.java)
   at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:896)
   at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:786)

视图寻呼机仅包含两个片段（v4）。我在以下代码中执行notifyDataSetChanged的行中收到错误。

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data); 

    if (resultCode == 100) {
        Handler handler = new Handler();
        handler.postDelayed(new Runnable() {
            @Override
            public void run() {
                mViewPager.getAdapter().notifyDataSetChanged();
            }
        }, 1000);
    }}

我是否需要在run方法中执行任何检查以检查活动是否仍然存在以避免此异常？

Answer 1

每当您使用Delay或回调访问实例变量或上下文时，您应首先检查其存在。

对于活动

Handler handler = new Handler();
    handler.postDelayed(new Runnable() {
        @Override
        public void run() {
            if(!isFinishing())
            mViewPager.getAdapter().notifyDataSetChanged();
        }
    }, 1000);

对于片段

Handler handler = new Handler();
    handler.postDelayed(new Runnable() {
        @Override
        public void run() {
            if(isAdded())
            mViewPager.getAdapter().notifyDataSetChanged();
        }
    }, 1000);