08-07 11:18:38.353: D/dalvikvm(15215): GC_FOR_ALLOC freed 83K, 6% free 12813K/13599K, paused 21ms
08-07 11:18:38.363: I/dalvikvm-heap(15215): Grow heap (frag case) to 15.352MB for 2908176-byte allocation
08-07 11:18:38.393: D/dalvikvm(15215): GC_FOR_ALLOC freed 1K, 6% free 15652K/16483K, paused 12ms
08-07 11:18:38.413: D/dalvikvm(15215): GC_CONCURRENT freed <1K, 6% free 15652K/16483K, paused 2ms+2ms
08-07 11:18:38.443: D/dalvikvm(15215): GC_FOR_ALLOC freed <1K, 6% free 15652K/16483K, paused 15ms
08-07 11:18:38.443: I/dalvikvm-heap(15215): Grow heap (frag case) to 20.281MB for 5169196-byte allocation
08-07 11:18:38.463: D/dalvikvm(15215): GC_FOR_ALLOC freed 0K, 4% free 20700K/21539K, paused 13ms
08-07 11:18:38.483: D/dalvikvm(15215): GC_CONCURRENT freed <1K, 4% free 20700K/21539K, paused 2ms+2ms
08-07 11:18:38.543: D/AndroidRuntime(15215): Shutting down VM
08-07 11:18:38.543: W/dalvikvm(15215): threadid=1: thread exiting with uncaught exception (group=0x40ab2210)
08-07 11:18:38.553: E/AndroidRuntime(15215): FATAL EXCEPTION: main
08-07 11:18:38.553: E/AndroidRuntime(15215): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.demo/com.example.demo.MainActivity}: java.lang.ClassCastException: android.widget.ImageView cannot be cast to android.widget.Button
08-07 11:18:38.553: E/AndroidRuntime(15215): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1967)
08-07 11:18:38.553: E/AndroidRuntime(15215): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1992)
08-07 11:18:38.553: E/AndroidRuntime(15215): at android.app.ActivityThread.access$600(ActivityThread.java:127)
08-07 11:18:38.553: E/AndroidRuntime(15215): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1158)
08-07 11:18:38.553: E/AndroidRuntime(15215): at android.os.Handler.dispatchMessage(Handler.java:99)
08-07 11:18:38.553: E/AndroidRuntime(15215): at android.os.Looper.loop(Looper.java:137)
08-07 11:18:38.553: E/AndroidRuntime(15215): at android.app.ActivityThread.main(ActivityThread.java:4441)
08-07 11:18:38.553: E/AndroidRuntime(15215): at java.lang.reflect.Method.invokeNative(Native Method)
08-07 11:18:38.553: E/AndroidRuntime(15215): at java.lang.reflect.Method.invoke(Method.java:511)
08-07 11:18:38.553: E/AndroidRuntime(15215): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:823)
08-07 11:18:38.553: E/AndroidRuntime(15215): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:590)
08-07 11:18:38.553: E/AndroidRuntime(15215): at dalvik.system.NativeStart.main(Native Method)
08-07 11:18:38.553: E/AndroidRuntime(15215): Caused by: java.lang.ClassCastException: android.widget.ImageView cannot be cast to android.widget.Button
08-07 11:18:38.553: E/AndroidRuntime(15215): at com.example.demo.MainActivity.onCreate(MainActivity.java:16)
08-07 11:18:38.553: E/AndroidRuntime(15215): at android.app.Activity.performCreate(Activity.java:4465)
08-07 11:18:38.553: E/AndroidRuntime(15215): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049)
08-07 11:18:38.553: E/AndroidRuntime(15215): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1931)
我可以运行简单的图形布局，但是当我尝试添加一些代码onclick或其他任何它向我显示这些错误。我从sdk管理器中删除了api 20并尝试在api17中编译。如何解决这些错误??????
答案 0 :(得分：0)
此异常表示您已将ImageView投射至Button。
Caused by: java.lang.ClassCastException: android.widget.ImageView cannot be cast to android.widget.Button
请在 MainActivity.java
中将(Button)更改为第16行 (ImageView)