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我想将ImageView移动到布局的顶部，以便它位于其他对象的后面。当我这样做时，它会崩溃。这工作，程序编译和运行：XML相对布局顺序更改崩溃程序（Android）
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".Nim" >
<TextView
android:id="@+id/tvTitle"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:text="@string/tvTitle"
android:textAppearance="?android:attr/textAppearanceLarge" />
<TextView
android:id="@+id/tvInfo"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@+id/tvTitle"
android:layout_centerHorizontal="true"
android:text="@string/tvInfo"
android:textAppearance="?android:attr/textAppearanceMedium" />
<SeekBar
android:id="@+id/sbMarbles"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_alignParentLeft="true"
android:layout_alignRight="@+id/tvInfo" />
<Button
android:id="@+id/butMarbles"
style="?android:attr/buttonStyleSmall"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_alignParentRight="true"
android:text="@string/butMarbles" />
<EditText
android:id="@+id/tvMarbles"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_toLeftOf="@+id/butMarbles"
android:layout_toRightOf="@+id/sbMarbles"
android:ems="10"
android:inputType="number" />
<TextView
android:id="@+id/tvInfo2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@+id/tvInfo"
android:layout_centerHorizontal="true"
android:layout_marginTop="43dp"
android:text="@string/tvInfo"
android:textAppearance="?android:attr/textAppearanceMedium" />
<Button
android:id="@+id/butYes"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@+id/tvInfo2"
android:layout_marginTop="83dp"
android:layout_toLeftOf="@+id/tvTitle"
android:text="@string/butYes" />
<Button
android:id="@+id/butNo"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBaseline="@+id/butYes"
android:layout_alignBottom="@+id/butYes"
android:layout_toRightOf="@+id/tvInfo2"
android:text="@string/butNo" />
<ImageView
android:id="@+id/bg"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:layout_centerVertical="true"
android:src="@drawable/marbles" />
</RelativeLayout>
但是，当我提出我的ImageView布局的顶部，一旦程序崩溃，我想不通为什么！这里是一个与logcat的一起导致程序崩溃的微小的变化：
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".Nim" >
<ImageView
android:id="@+id/bg"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:layout_centerVertical="true"
android:src="@drawable/marbles" />
<TextView
android:id="@+id/tvTitle"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:text="@string/tvTitle"
android:textAppearance="?android:attr/textAppearanceLarge" />
<TextView
android:id="@+id/tvInfo"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@+id/tvTitle"
android:layout_centerHorizontal="true"
android:text="@string/tvInfo"
android:textAppearance="?android:attr/textAppearanceMedium" />
<SeekBar
android:id="@+id/sbMarbles"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_alignParentLeft="true"
android:layout_alignRight="@+id/tvInfo" />
<Button
android:id="@+id/butMarbles"
style="?android:attr/buttonStyleSmall"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_alignParentRight="true"
android:text="@string/butMarbles" />
<EditText
android:id="@+id/tvMarbles"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_toLeftOf="@+id/butMarbles"
android:layout_toRightOf="@+id/sbMarbles"
android:ems="10"
android:inputType="number" />
<TextView
android:id="@+id/tvInfo2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@+id/tvInfo"
android:layout_centerHorizontal="true"
android:layout_marginTop="43dp"
android:text="@string/tvInfo"
android:textAppearance="?android:attr/textAppearanceMedium" />
<Button
android:id="@+id/butYes"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@+id/tvInfo2"
android:layout_marginTop="83dp"
android:layout_toLeftOf="@+id/tvTitle"
android:text="@string/butYes" />
<Button
android:id="@+id/butNo"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBaseline="@+id/butYes"
android:layout_alignBottom="@+id/butYes"
android:layout_toRightOf="@+id/tvInfo2"
android:text="@string/butNo" />
</RelativeLayout>
01-07 21:00:00.453: E/AndroidRuntime(568): FATAL EXCEPTION: main
01-07 21:00:00.453: E/AndroidRuntime(568): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.evorlor.gameofnim/com.evorlor.gameofnim.Nim}: java.lang.ClassCastException: android.widget.TextView
01-07 21:00:00.453: E/AndroidRuntime(568): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1647)
01-07 21:00:00.453: E/AndroidRuntime(568): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663)
01-07 21:00:00.453: E/AndroidRuntime(568): at android.app.ActivityThread.access$1500(ActivityThread.java:117)
01-07 21:00:00.453: E/AndroidRuntime(568): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931)
01-07 21:00:00.453: E/AndroidRuntime(568): at android.os.Handler.dispatchMessage(Handler.java:99)
01-07 21:00:00.453: E/AndroidRuntime(568): at android.os.Looper.loop(Looper.java:123)
01-07 21:00:00.453: E/AndroidRuntime(568): at android.app.ActivityThread.main(ActivityThread.java:3683)
01-07 21:00:00.453: E/AndroidRuntime(568): at java.lang.reflect.Method.invokeNative(Native Method)
01-07 21:00:00.453: E/AndroidRuntime(568): at java.lang.reflect.Method.invoke(Method.java:507)
01-07 21:00:00.453: E/AndroidRuntime(568): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
01-07 21:00:00.453: E/AndroidRuntime(568): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
01-07 21:00:00.453: E/AndroidRuntime(568): at dalvik.system.NativeStart.main(Native Method)
01-07 21:00:00.453: E/AndroidRuntime(568): Caused by: java.lang.ClassCastException: android.widget.TextView
01-07 21:00:00.453: E/AndroidRuntime(568): at com.evorlor.gameofnim.Nim.listener(Nim.java:56)
01-07 21:00:00.453: E/AndroidRuntime(568): at com.evorlor.gameofnim.Nim.onCreate(Nim.java:41)
01-07 21:00:00.453: E/AndroidRuntime(568): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
01-07 21:00:00.453: E/AndroidRuntime(568): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1611)
01-07 21:00:00.453: E/AndroidRuntime(568): ... 11 more
01-07 21:18:20.403: E/AndroidRuntime(704): FATAL EXCEPTION: main
01-07 21:18:20.403: E/AndroidRuntime(704): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.evorlor.gameofnim/com.evorlor.gameofnim.Opening}: java.lang.NullPointerException
01-07 21:18:20.403: E/AndroidRuntime(704): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1647)
01-07 21:18:20.403: E/AndroidRuntime(704): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663)
01-07 21:18:20.403: E/AndroidRuntime(704): at android.app.ActivityThread.access$1500(ActivityThread.java:117)
01-07 21:18:20.403: E/AndroidRuntime(704): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931)
01-07 21:18:20.403: E/AndroidRuntime(704): at android.os.Handler.dispatchMessage(Handler.java:99)
01-07 21:18:20.403: E/AndroidRuntime(704): at android.os.Looper.loop(Looper.java:123)
01-07 21:18:20.403: E/AndroidRuntime(704): at android.app.ActivityThread.main(ActivityThread.java:3683)
01-07 21:18:20.403: E/AndroidRuntime(704): at java.lang.reflect.Method.invokeNative(Native Method)
01-07 21:18:20.403: E/AndroidRuntime(704): at java.lang.reflect.Method.invoke(Method.java:507)
01-07 21:18:20.403: E/AndroidRuntime(704): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
01-07 21:18:20.403: E/AndroidRuntime(704): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
01-07 21:18:20.403: E/AndroidRuntime(704): at dalvik.system.NativeStart.main(Native Method)
01-07 21:18:20.403: E/AndroidRuntime(704): Caused by: java.lang.NullPointerException
01-07 21:18:20.403: E/AndroidRuntime(704): at com.evorlor.gameofnim.Opening.listener(Opening.java:36)
01-07 21:18:20.403: E/AndroidRuntime(704): at com.evorlor.gameofnim.Opening.onCreate(Opening.java:28)
01-07 21:18:20.403: E/AndroidRuntime(704): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
01-07 21:18:20.403: E/AndroidRuntime(704): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1611)
01-07 21:18:20.403: E/AndroidRuntime(704): ... 11 more
01-07 21:19:32.743: E/AndroidRuntime(737): FATAL EXCEPTION: main
01-07 21:19:32.743: E/AndroidRuntime(737): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.evorlor.gameofnim/com.evorlor.gameofnim.Opening}: java.lang.NullPointerException
01-07 21:19:32.743: E/AndroidRuntime(737): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1647)
01-07 21:19:32.743: E/AndroidRuntime(737): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663)
01-07 21:19:32.743: E/AndroidRuntime(737): at android.app.ActivityThread.access$1500(ActivityThread.java:117)
01-07 21:19:32.743: E/AndroidRuntime(737): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931)
01-07 21:19:32.743: E/AndroidRuntime(737): at android.os.Handler.dispatchMessage(Handler.java:99)
01-07 21:19:32.743: E/AndroidRuntime(737): at android.os.Looper.loop(Looper.java:123)
01-07 21:19:32.743: E/AndroidRuntime(737): at android.app.ActivityThread.main(ActivityThread.java:3683)
01-07 21:19:32.743: E/AndroidRuntime(737): at java.lang.reflect.Method.invokeNative(Native Method)
01-07 21:19:32.743: E/AndroidRuntime(737): at java.lang.reflect.Method.invoke(Method.java:507)
01-07 21:19:32.743: E/AndroidRuntime(737): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
01-07 21:19:32.743: E/AndroidRuntime(737): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
01-07 21:19:32.743: E/AndroidRuntime(737): at dalvik.system.NativeStart.main(Native Method)
01-07 21:19:32.743: E/AndroidRuntime(737): Caused by: java.lang.NullPointerException
01-07 21:19:32.743: E/AndroidRuntime(737): at com.evorlor.gameofnim.Opening.listener(Opening.java:36)
01-07 21:19:32.743: E/AndroidRuntime(737): at com.evorlor.gameofnim.Opening.onCreate(Opening.java:28)
01-07 21:19:32.743: E/AndroidRuntime(737): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
01-07 21:19:32.743: E/AndroidRuntime(737): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1611)
01-07 21:19:32.743: E/AndroidRuntime(737): ... 11 more
01-07 21:23:52.323: E/AndroidRuntime(747): FATAL EXCEPTION: main
01-07 21:23:52.323: E/AndroidRuntime(747): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.evorlor.gameofnim/com.evorlor.gameofnim.Opening}: java.lang.NullPointerException
01-07 21:23:52.323: E/AndroidRuntime(747): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1647)
01-07 21:23:52.323: E/AndroidRuntime(747): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663)
01-07 21:23:52.323: E/AndroidRuntime(747): at android.app.ActivityThread.access$1500(ActivityThread.java:117)
01-07 21:23:52.323: E/AndroidRuntime(747): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931)
01-07 21:23:52.323: E/AndroidRuntime(747): at android.os.Handler.dispatchMessage(Handler.java:99)
01-07 21:23:52.323: E/AndroidRuntime(747): at android.os.Looper.loop(Looper.java:123)
01-07 21:23:52.323: E/AndroidRuntime(747): at android.app.ActivityThread.main(ActivityThread.java:3683)
01-07 21:23:52.323: E/AndroidRuntime(747): at java.lang.reflect.Method.invokeNative(Native Method)
01-07 21:23:52.323: E/AndroidRuntime(747): at java.lang.reflect.Method.invoke(Method.java:507)
01-07 21:23:52.323: E/AndroidRuntime(747): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
01-07 21:23:52.323: E/AndroidRuntime(747): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
01-07 21:23:52.323: E/AndroidRuntime(747): at dalvik.system.NativeStart.main(Native Method)
01-07 21:23:52.323: E/AndroidRuntime(747): Caused by: java.lang.NullPointerException
01-07 21:23:52.323: E/AndroidRuntime(747): at com.evorlor.gameofnim.Opening.listener(Opening.java:36)
01-07 21:23:52.323: E/AndroidRuntime(747): at com.evorlor.gameofnim.Opening.onCreate(Opening.java:28)
01-07 21:23:52.323: E/AndroidRuntime(747): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
01-07 21:23:52.323: E/AndroidRuntime(747): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1611)
01-07 21:23:52.323: E/AndroidRuntime(747): ... 11 more
01-07 21:33:28.122: E/AndroidRuntime(813): FATAL EXCEPTION: main
01-07 21:33:28.122: E/AndroidRuntime(813): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.evorlor.gameofnim/com.evorlor.gameofnim.Opening}: java.lang.NullPointerException
01-07 21:33:28.122: E/AndroidRuntime(813): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1647)
01-07 21:33:28.122: E/AndroidRuntime(813): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663)
01-07 21:33:28.122: E/AndroidRuntime(813): at android.app.ActivityThread.access$1500(ActivityThread.java:117)
01-07 21:33:28.122: E/AndroidRuntime(813): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931)
01-07 21:33:28.122: E/AndroidRuntime(813): at android.os.Handler.dispatchMessage(Handler.java:99)
01-07 21:33:28.122: E/AndroidRuntime(813): at android.os.Looper.loop(Looper.java:123)
01-07 21:33:28.122: E/AndroidRuntime(813): at android.app.ActivityThread.main(ActivityThread.java:3683)
01-07 21:33:28.122: E/AndroidRuntime(813): at java.lang.reflect.Method.invokeNative(Native Method)
01-07 21:33:28.122: E/AndroidRuntime(813): at java.lang.reflect.Method.invoke(Method.java:507)
01-07 21:33:28.122: E/AndroidRuntime(813): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
01-07 21:33:28.122: E/AndroidRuntime(813): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
01-07 21:33:28.122: E/AndroidRuntime(813): at dalvik.system.NativeStart.main(Native Method)
01-07 21:33:28.122: E/AndroidRuntime(813): Caused by: java.lang.NullPointerException
01-07 21:33:28.122: E/AndroidRuntime(813): at com.evorlor.gameofnim.Opening.listener(Opening.java:36)
01-07 21:33:28.122: E/AndroidRuntime(813): at com.evorlor.gameofnim.Opening.onCreate(Opening.java:28)
01-07 21:33:28.122: E/AndroidRuntime(813): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
01-07 21:33:28.122: E/AndroidRuntime(813): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1611)
01-07 21:33:28.122: E/AndroidRuntime(813): ... 11 more
谢谢！
您是否清理并运行该项目？我有时会遇到这种奇怪的行为。 –
清洁并运行？ – Evorlor
清理项目，然后运行 –