Question

我有一个快餐栏，我想要删除textview，但是当我使用View.INVISIBLE时它没有显示uo但是当使用View.GONE时，app会因为说NullPointerException而崩溃。为什么这样？

这是代码

MainActivity.java

Snackbar sk=Snackbar.make(findViewById(R.id.ll),"It is checked",Snackbar.LENGTH_INDEFINITE);
sk.setAction("Undo",m);
sk.setActionTextColor(Color.GREEN);       

Snackbar.SnackbarLayout sl = (Snackbar.SnackbarLayout) sk.getView();

TextView t=sl.findViewById(android.support.design.R.id.snackbar_text);
t.setVisibility(View.GONE);

logcat的

致命的例外：主要处理：com.example.ankit.testing，PID：29950 java.lang.NullPointerException：尝试调用虚方法＆＃39; int android.text.Layout.getLineCount（）＆＃39;在null对象引用上在android.support.design.internal.SnackbarContentLayout.onMeasure（SnackbarContentLayout.java:85）在android.view.View.measure（View.java:18820）在android.view.ViewGroup.measureChildWithMargins（ViewGroup.java:5961）在android.widget.FrameLayout.onMeasure（FrameLayout.java:194）在android.support.design.widget.Snackbar $ SnackbarLayout.onMeasure（Snackbar.java:335）在android.view.View.measure（View.java:18820）在android.view.ViewGroup.measureChildWithMargins（ViewGroup.java:5961）在android.widget.FrameLayout.onMeasure（FrameLayout.java:194）在android.support.v7.widget.ContentFrameLayout.onMeasure（ContentFrameLayout.java:139）在android.view.View.measure（View.java:18820）在android.view.ViewGroup.measureChildWithMargins（ViewGroup.java:5961）在android.support.v7.widget.ActionBarOverlayLayout.onMeasure（ActionBarOverlayLayout.java:391）在android.view.View.measure（View.java:18820）在android.view.ViewGroup.measureChildWithMargins（ViewGroup.java:5961）在android.widget.FrameLayout.onMeasure（FrameLayout.java:194）在android.view.View.measure（View.java:18820）在android.view.ViewGroup.measureChildWithMargins（ViewGroup.java:5961）在android.widget.LinearLayout.measureChildBeforeLayout（LinearLayout.java:1465）在android.widget.LinearLayout.measureVertical（LinearLayout.java:748）在android.widget.LinearLayout.onMeasure（LinearLayout.java:630）在android.view.View.measure（View.java:18820）在android.view.ViewGroup.measureChildWithMargins（ViewGroup.java:5961）在android.widget.FrameLayout.onMeasure（FrameLayout.java:194）在com.android.internal.policy.PhoneWindow $ DecorView.onMeasure（PhoneWindow.java:2680）在android.view.View.measure（View.java:18820）在android.view.ViewRootImpl.performMeasure（ViewRootImpl.java:2132）在android.view.ViewRootImpl.measureHierarchy（ViewRootImpl.java:1248）在android.view.ViewRootImpl.performTraversals（ViewRootImpl.java:1484）在android.view.ViewRootImpl.doTraversal（ViewRootImpl.java:1139）在android.view.ViewRootImpl $ TraversalRunnable.run（ViewRootImpl.java:6091）在android.view.Choreographer $ CallbackRecord.run（Choreographer.java:858）在android.view.Choreographer.doCallbacks（Choreographer.java:670）在android.view.Choreographer.doFrame（Choreographer.java:606）在android.view.Choreographer $ FrameDisplayEventReceiver.run（Choreographer.java:844）在android.os.Handler.handleCallback（Handler.java:739）在android.os.Handler.dispatchMessage（Handler.java:95）在android.os.Looper.loop（Looper.java:148）在android.app.ActivityThread.main（ActivityThread.java:5437） at java.lang.reflect.Method.invoke（Native Method）在com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run（ZygoteInit.java:726）在com.android.internal.os.ZygoteInit.main（ZygoteInit.java:616）

Answer 1

首先尝试创建像这样的Snackbar

 // Create the Snackbar
Snackbar snackbar = Snackbar.make(containerLayout, "", Snackbar.LENGTH_LONG);

获取Snackbar的布局视图

 Snackbar.SnackbarLayout layout = (Snackbar.SnackbarLayout) snackbar.getView();

隐藏像这样的小吃吧文本

 TextView textView = (TextView) layout.findViewById(android.support.design.R.id.snackbar_text);
    textView.setVisibility(View.INVISIBLE);

将文字设置为此类小吃吧

TextView textViewTop = (TextView)    
snackView.findViewById(R.id.text);
textViewTop.setText(text);

将视图添加到Snackbar的布局

layout.addView(snackView, 0);

显示Snackbar

snackbar.show();

为什么View.Gone无法在Snackbar中工作？

1 个答案: