Question

我的应用程序中有两个消息列表，传入和传出。这两个列表放在片段上，这些片段又在SlidingTab中。因此，事实证明，当您打开带有这些选项卡的屏幕时，始终会发送来自片段的两个请求以接收两个消息列表。但是我只需要在选择适当的选项卡时才能激活片段。因为当我的access_token死亡时，我有两个请求令牌更新请求，并且其中一个请求必须从服务器返回错误。

UPD：

我的错误日志：

08-16 16:16:24.135 E: FATAL EXCEPTION: main
    Process: com.example.developer_4.test_login, PID: 10852
    java.lang.NullPointerException
        at java.util.Objects.requireNonNull(Objects.java:203)
        at com.example.developer_4.test_login.Tabs.Sent.sent(Sent.java:92)
        at com.example.developer_4.test_login.Tabs.Sent.setUserVisibleHint(Sent.java:70)
        at android.support.v4.app.FragmentStatePagerAdapter.setPrimaryItem(FragmentStatePagerAdapter.java:160)
        at android.support.v4.view.ViewPager.populate(ViewPager.java:1234)
        at android.support.v4.view.ViewPager.populate(ViewPager.java:1092)
        at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1622)
        at android.view.View.measure(View.java:19857)
        at android.widget.RelativeLayout.measureChildHorizontal(RelativeLayout.java:715)
        at android.widget.RelativeLayout.onMeasure(RelativeLayout.java:461)
        at android.view.View.measure(View.java:19857)
        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6083)
        at android.support.design.widget.CoordinatorLayout.onMeasureChild(CoordinatorLayout.java:733)
        at android.support.design.widget.HeaderScrollingViewBehavior.onMeasureChild(HeaderScrollingViewBehavior.java:95)
        at android.support.design.widget.AppBarLayout$ScrollingViewBehavior.onMeasureChild(AppBarLayout.java:1556)
        at android.support.design.widget.CoordinatorLayout.onMeasure(CoordinatorLayout.java:803)
        at android.view.View.measure(View.java:19857)
        at android.support.v4.widget.DrawerLayout.onMeasure(DrawerLayout.java:1119)
        at android.view.View.measure(View.java:19857)
        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6083)
        at android.widget.FrameLayout.onMeasure(FrameLayout.java:185)
        at android.support.v7.widget.ContentFrameLayout.onMeasure(ContentFrameLayout.java:143)
        at android.view.View.measure(View.java:19857)
        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6083)
        at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1464)
        at android.widget.LinearLayout.measureVertical(LinearLayout.java:758)
        at android.widget.LinearLayout.onMeasure(LinearLayout.java:640)
        at android.view.View.measure(View.java:19857)
        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6083)
        at android.widget.FrameLayout.onMeasure(FrameLayout.java:185)
        at android.view.View.measure(View.java:19857)
        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6083)
        at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1464)
        at android.widget.LinearLayout.measureVertical(LinearLayout.java:758)
        at android.widget.LinearLayout.onMeasure(LinearLayout.java:640)
        at android.view.View.measure(View.java:19857)
        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6083)
        at android.widget.FrameLayout.onMeasure(FrameLayout.java:185)
        at com.android.internal.policy.DecorView.onMeasure(DecorView.java:689)
        at android.view.View.measure(View.java:19857)
        at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:2275)
        at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1366)
        at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1619)
        at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1254)
        at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:6337)
        at android.view.Choreographer$CallbackRecord.run(Choreographer.java:874)
        at android.view.Choreographer.doCallbacks(Choreographer.java:686)
        at android.view.Choreographer.doFrame(Choreographer.java:621)
        at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:860)
        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:6119)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)

第92行：

access_token = Objects.requireNonNull(getActivity()).getSharedPreferences(ACCESS_TOKEN, Context.MODE_PRIVATE);

第70行：

@Override
    public void setUserVisibleHint(boolean isVisibleToUser) {
        super.setUserVisibleHint(isVisibleToUser);
        if (isVisibleToUser) {
            sent(); - line 70
        }
    }

帮助请解决此问题。

Answer 1

您可以覆盖片段中的setUserVisibleHint并在可见片段时进行API调用。

@Override
public void setUserVisibleHint(boolean isVisibleToUser) {
    super.setUserVisibleHint(isVisibleToUser);
    if (isVisibleToUser) {
        //make Api Call here
    }
}

编辑

   private boolean isVisible;
   private boolean isStarted;

    @Override
    public void onStart() {
        super.onStart();
        isStarted = true;
        if (isVisible){
            //make Api Call here
        }
    }

    @Override
    public void onStop() {
        super.onStop();
        isStarted = false;
    }

    @Override
    public void setUserVisibleHint(boolean isVisibleToUser) {
        super.setUserVisibleHint(isVisibleToUser);
        isVisible = isVisibleToUser;
        if (isVisible && isStarted){
            //make Api Call here
        }
    }

是否可以在滑动标签中打开某些片段？

UPD：

1 个答案: