Question

将以下相对布局和嵌套元素（ImageView，TextView）添加到主布局后，我的应用程序在打开时关闭，错误为java.lang.ClassCastException: android.widget.ImageView cannot be cast to android.widget.TextView：

这是stacktrace：

E/AndroidRuntime: FATAL EXCEPTION: main
     Process: com.fogtechnologies.expotec.urban, PID: 2898
     java.lang.RuntimeException: Unable to start activity ComponentInfo{com.fogtechnologies.expotec.urban/com.fogtechnologies.expotecshell.urban.activities.ActivityExpotecMainView}: java.lang.ClassCastException: android.widget.ImageView cannot be cast to android.widget.TextView
     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2195)
     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
     at android.app.ActivityThread.access$800(ActivityThread.java:135)
     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
     at android.os.Handler.dispatchMessage(Handler.java:102)
     at android.os.Looper.loop(Looper.java:136)
     at android.app.ActivityThread.main(ActivityThread.java:5017)
     at java.lang.reflect.Method.invokeNative(Native Method)
     at java.lang.reflect.Method.invoke(Method.java:515)
     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
     at dalvik.system.NativeStart.mai(Native Method)
Caused by: java.lang.ClassCastException: android.widget.ImageView cannot be cast to android.widget.TextView
     at com.fogtechnologies.expotecshell.urban.activities.ActivityExpotecMainView.findViews(ActivityExpotecMainView.java:163)
     at com.fogtechnologies.expotecshell.urban.activities.ActivityExpotecMainView.onCreate(ActivityExpotecMainView.java:77)
     at android.app.Activity.performCreate(Activity.java:5231)
     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2159)
     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245) 
     at android.app.ActivityThread.access$800(ActivityThread.java:135) 
     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196) 
     at android.os.Handler.dispatchMessage(Handler.java:102) 
     at android.os.Looper.loop(Looper.java:136) 
     at android.app.ActivityThread.main(ActivityThread.java:5017) 
     at java.lang.reflect.Method.invokeNative(Native Method) 
     at java.lang.reflect.Method.invoke(Method.java:515) 
     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779) 
     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595) 
     at dalvik.system.NativeStart.main(Native Method)

以下是我的布局文件中的代码段：

<RelativeLayout
    android:id="@+id/RelativeLayout2"
    android:layout_width="match_parent"
    android:layout_height="wrap_content" >

    <ImageView
        android:id="@+id/tvMainDownloadEvent"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginLeft="80dp"
        android:layout_marginRight="80dp"
        android:textColor="@color/white"
        android:onClick="downloadEventButtonAction"
        android:src="@drawable/now_performing_shape"
        android:scaleX="0.8"
        android:scaleY="0.8" />

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@id/tvMainDownloadEvent"
        android:layout_alignTop="@id/tvMainDownloadEvent"
        android:layout_alignRight="@id/tvMainDownloadEvent"
        android:layout_alignBottom="@id/tvMainDownloadEvent"
        android:layout_margin="1dp"
        android:gravity="center"
        android:textColor="@color/white"
        android:textSize="16sp"
        android:scaleX="0.9"
        android:scaleY="0.9"
        android:text="Download Event" />

</RelativeLayout>

```

以下是问题的代码行：

tvMainDownloadEvent = (TextView) findViewById(R.id.tvMainDownloadEvent);

将(TextView)更改为(ImageView)并不能解决此问题。

如何将ID的类型更改为ImageView？

Answer 1

您的Logcat会抛出 ClassCastException

抛出以指示代码已尝试将对象强制转换为它不是实例的子类。

问题从

开始

 android:id="@+id/tvMainDownloadEvent"

是 TextView ID。请勿在 ImageView 部分设置此内容。

您应该从Java类中更改它。

Answer 2

问题出在你的java代码中，而不是xml中。您最有可能在TextView方法中使用了ImageView和findViewById()个ID。

Answer 3

将tvMainDownloadEvent用于textview，将ivMainDownloadEvent用于imageview。

将布局更改为

<RelativeLayout
    android:id="@+id/RelativeLayout2"
    android:layout_width="match_parent"
    android:layout_height="wrap_content" >

    <ImageView
        android:id="@+id/ivMainDownloadEvent"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginLeft="80dp"
        android:layout_marginRight="80dp"
        android:textColor="@color/white"
        android:onClick="downloadEventButtonAction"
        android:src="@drawable/now_performing_shape"
        android:scaleX="0.8"
        android:scaleY="0.8" />

    <TextView
        android:id="@+id/tvMainDownloadEvent"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@id/ivMainDownloadEvent"
        android:layout_alignTop="@id/ivMainDownloadEvent"
        android:layout_alignRight="@id/ivMainDownloadEvent"
        android:layout_alignBottom="@id/ivMainDownloadEvent"
        android:layout_margin="1dp"
        android:gravity="center"
        android:textColor="@color/white"
        android:textSize="16sp"
        android:scaleX="0.9"
        android:scaleY="0.9"
        android:text="Download Event" />

</RelativeLayout>

ImageView无法强制转换为android.widget.TextView

3 个答案: