ListView GetView中的位置错误

Question

我在 GetView 中遇到错误，我认为问题出在位置变量上，但我尝试的所有操作都无法更改 anything.The ListView 设置为显示 WebView 的 UrlHistory。我相信这就是当我为它打开 activity 时我的 ListVies 不可见的原因。如果不是，那么我将不得不稍后弄清楚。关于 log.e 我想看看我是否能看到它是否在 LogCat 中获取数据，但我找不到它在 LogCat.

中的特定行

UrlHistoryAdapter.Java

public View getView(int position, View convertView, ViewGroup parent) {
    View view = convertView;
    if (view == null) {
        view = 
LayoutInflater.from(context).inflate(R.layout.list_item,parent,false);
    }

    TextView textView = view.findViewById(android.R.id.title);
    textView.setText(getItem(position));

    Log.e(Tag, "received data");
    return view;
}

LogCat

02-02 16:33:04.424 26544-26544/com.example.mickeyt.onyxbrowser E/AndroidRuntime: FATAL EXCEPTION: main
                                                                             Process: com.example.mickeyt.onyxbrowser, PID: 26544
                                                                             java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.TextView.setText(java.lang.CharSequence)' on a null object reference
                                                                                 at com.example.mickeyt.onyxbrowser.UrlHistoryAdapter.getView(UrlHistoryAdapter.java:60)
                                                                                 at android.widget.AbsListView.obtainView(AbsListView.java:2406)
                                                                                 at android.widget.ListView.makeAndAddView(ListView.java:1975)
                                                                                 at android.widget.ListView.fillDown(ListView.java:709)
                                                                                 at android.widget.ListView.fillFromTop(ListView.java:770)
                                                                                 at android.widget.ListView.layoutChildren(ListView.java:1721)
                                                                                 at android.widget.AbsListView.onLayout(AbsListView.java:2205)
                                                                                 at android.view.View.layout(View.java:17564)
                                                                                 at android.view.ViewGroup.layout(ViewGroup.java:5654)
                                                                                 at android.support.constraint.ConstraintLayout.onLayout(ConstraintLayout.java:1197)
                                                                                 at android.view.View.layout(View.java:17564)
                                                                                 at android.view.ViewGroup.layout(ViewGroup.java:5654)
                                                                                 at android.support.constraint.ConstraintLayout.onLayout(ConstraintLayout.java:1197)
                                                                                 at android.view.View.layout(View.java:17564)
                                                                                 at android.view.ViewGroup.layout(ViewGroup.java:5654)
                                                                                 at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
                                                                                 at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
                                                                                 at android.view.View.layout(View.java:17564)
                                                                                 at android.view.ViewGroup.layout(ViewGroup.java:5654)
                                                                                 at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1741)
                                                                                 at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1585)
                                                                                 at android.widget.LinearLayout.onLayout(LinearLayout.java:1494)
                                                                                 at android.view.View.layout(View.java:17564)
                                                                                 at android.view.ViewGroup.layout(ViewGroup.java:5654)
                                                                                 at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
                                                                                 at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
                                                                                 at android.view.View.layout(View.java:17564)
                                                                                 at android.view.ViewGroup.layout(ViewGroup.java:5654)
                                                                                 at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1741)
                                                                                 at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1585)
                                                                                 at android.widget.LinearLayout.onLayout(LinearLayout.java:1494)
                                                                                 at android.view.View.layout(View.java:17564)
                                                                                 at android.view.ViewGroup.layout(ViewGroup.java:5654)
                                                                                 at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
                                                                                 at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
                                                                                 at com.android.internal.policy.DecorView.onLayout(DecorView.java:725)
                                                                                 at android.view.View.layout(View.java:17564)
                                                                                 at android.view.ViewGroup.layout(ViewGroup.java:5654)
                                                                                 at android.view.ViewRootImpl.performLayout(ViewRootImpl.java:2406)
                                                                                 at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:2126)
                                                                                 at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1286)
                                                                                 at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:6536)
                                                                                 at android.view.Choreographer$CallbackRecord.run(Choreographer.java:871)
                                                                                 at android.view.Choreographer.doCallbacks(Choreographer.java:683)
                                                                                 at android.view.Choreographer.doFrame(Choreographer.java:619)
                                                                                 at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:857)
                                                                                 at android.os.Handler.handleCallback(Handler.java:751)
                                                                                 at android.os.Handler.dispatchMessage(Handler.java:95)
                                                                                 at android.os.Looper.loop(Looper.java:154)
                                                                                 at android.app.ActivityThread.main(ActivityThread.java:6247)
                                                                                 at java.lang.reflect.Method.invoke(Native Method)
                                                                                 at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:872)
                                                                                 at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:762)

Answer 1

它说你的 TextView 是空的。检查它为什么为空。

OBS：我建议你使用RecyclerView。

Answer 2

您的问题出在这一行：

TextView textView = view.findViewById(android.R.id.title);

view 布局不包含 ID 为 android.R.id.title 的视图。
我认为问题在于您使用 android.R.id.title 而不是 R.id.title （开头没有 android）。
因此，为了解决这个问题，您应该将 android.R.id.title 更改为 R.id.title

Answer 3

您的文本视图为空，

尝试.. textView.setText(getItem(position).toString) 或者.. textView.setText(getItem(position)+" ")

ListView GetView中的位置错误

Position error in ListView GetView

android

listview

android-arrayadapter