Android XML文件java.lang.nullpointerexception（Android xml文件中为什么id属性会标红）

25-02-11 15

在本文中，我们将详细介绍AndroidXML文件java.lang.nullpointerexception的各个方面，并为您提供关于Androidxml文件中为什么id属性会标红的相关解答，同时，我

在本文中，我们将详细介绍Android XML文件java.lang.nullpointerexception的各个方面，并为您提供关于Android xml文件中为什么id属性会标红的相关解答，同时，我们也将为您带来关于Android AVD Manager：无法创建新的设备定义(java.lang.NullPointerException)、Android java.lang.RuntimeException：无法实例化活动ComponentInfo … java.lang.NullPointerException、Android sdk：java.lang.NullPointerException：尝试调用虚方法、Android Studio：取消装箱“ xxx”可能会产生“ java.lang.NullPointerException”的有用知识。

本文目录一览：

Android XML文件java.lang.nullpointerexception（Android xml文件中为什么id属性会标红）
Android AVD Manager：无法创建新的设备定义(java.lang.NullPointerException)
Android java.lang.RuntimeException：无法实例化活动ComponentInfo … java.lang.NullPointerException
Android sdk：java.lang.NullPointerException：尝试调用虚方法
Android Studio：取消装箱“ xxx”可能会产生“ java.lang.NullPointerException”

Android XML文件java.lang.nullpointerexception（Android xml文件中为什么id属性会标红）

我正在建立一个全新的android项目。这不是我的第一个android应用程序，所以我更沮丧的是无法摆脱此错误…

我使用的XML文件目前只有3个项目，并且XML标签中没有错误：

<?xml version="1.0" encoding="utf-8"?><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:id="@+id/container"    android:layout_width="match_parent"    android:layout_height="match_parent"    tools:context=".gaming..MainActivity" >    <ImageView        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:background="@drawable/fondipad"        android:contentDescription="@string/FondDesc"        />    <RelativeLayout         android:layout_height="300dp"         android:layout_width="fill_parent"        android:background="@drawable/cadremenu">    </RelativeLayout>     </RelativeLayout>

很简单，是吗？但是，视觉选项卡不会使cadremenu可绘制（但“喜欢”会呈现）…但是cadremenu.png在drawable文件夹中！我可以启动应用程序，但只渲染背景…我真的不知道该怎么办…
xml文件返回此异常

java.lang.NullPointerException    at android.graphics.Bitmap_Delegate.createBitmap(Bitmap_Delegate.java:598)    at android.graphics.Bitmap_Delegate.createBitmap(Bitmap_Delegate.java:120)    at android.graphics.Bitmap_Delegate.createBitmap(Bitmap_Delegate.java:102)    at com.android.layoutlib.bridge.impl.ResourceHelper.getDrawable(ResourceHelper.java:233)    at android.content.res.BridgeTypedArray.getDrawable(BridgeTypedArray.java:782)    at android.view.View.<init>(View.java:3554)    at android.view.View.<init>(View.java:3484)    at android.view.ViewGroup.<init>(ViewGroup.java:464)    at android.widget.RelativeLayout.<init>(RelativeLayout.java:236)    at sun.reflect.GeneratedConstructorAccessor37.newInstance(Unknown Source)    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)    at java.lang.reflect.Constructor.newInstance(Constructor.java:513)    at android.view.LayoutInflater.createView(LayoutInflater.java:594)    at android.view.BridgeInflater.onCreateView(BridgeInflater.java:86)    at android.view.LayoutInflater.onCreateView(LayoutInflater.java:669)    at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:694)    at android.view.BridgeInflater.createViewFromTag(BridgeInflater.java:131)    at android.view.LayoutInflater.rInflate_Original(LayoutInflater.java:755)    at android.view.LayoutInflater_Delegate.rInflate(LayoutInflater_Delegate.java:64)    at android.view.LayoutInflater.rInflate(LayoutInflater.java:727)    at android.view.LayoutInflater.inflate(LayoutInflater.java:492)    at android.view.LayoutInflater.inflate(LayoutInflater.java:373)    at com.android.layoutlib.bridge.impl.RenderSessionImpl.inflate(RenderSessionImpl.java:399)    at com.android.layoutlib.bridge.Bridge.createSession(Bridge.java:336)    at com.android.ide.common.rendering.LayoutLibrary.createSession(LayoutLibrary.java:332)    at com.android.ide.eclipse.adt.internal.editors.layout.gle2.RenderService.createRenderSession(RenderService.java:504)    at com.android.ide.eclipse.adt.internal.editors.layout.gle2.GraphicalEditorPart.renderWithBridge(GraphicalEditorPart.java:1584)    at com.android.ide.eclipse.adt.internal.editors.layout.gle2.GraphicalEditorPart.recomputeLayout(GraphicalEditorPart.java:1309)    at com.android.ide.eclipse.adt.internal.editors.layout.gle2.GraphicalEditorPart.activated(GraphicalEditorPart.java:1066)    at com.android.ide.eclipse.adt.internal.editors.layout.LayoutEditorDelegate.delegatePageChange(LayoutEditorDelegate.java:686)    at com.android.ide.eclipse.adt.internal.editors.common.CommonXmlEditor.pageChange(CommonXmlEditor.java:360)    at org.eclipse.ui.part.MultiPageEditorPart$2.widgetSelected(MultiPageEditorPart.java:292)    at org.eclipse.swt.widgets.TypedListener.handleEvent(TypedListener.java:248)    at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:84)    at org.eclipse.swt.widgets.Display.sendEvent(Display.java:4136)    at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1458)    at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1481)    at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1466)    at org.eclipse.swt.widgets.Widget.notifyListeners(Widget.java:1271)    at org.eclipse.swt.custom.CTabFolder.setSelection(CTabFolder.java:3028)    at org.eclipse.swt.custom.CTabFolder.onMouse(CTabFolder.java:1749)    at org.eclipse.swt.custom.CTabFolder$1.handleEvent(CTabFolder.java:278)    at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:84)    at org.eclipse.swt.widgets.Display.sendEvent(Display.java:4136)    at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1458)    at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1481)    at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1466)    at org.eclipse.swt.widgets.Widget.notifyListeners(Widget.java:1271)    at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:3982)    at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3621)    at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine$9.run(PartRenderingEngine.java:1053)    at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332)    at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.run(PartRenderingEngine.java:942)    at org.eclipse.e4.ui.internal.workbench.E4Workbench.createAndRunUI(E4Workbench.java:86)    at org.eclipse.ui.internal.Workbench$5.run(Workbench.java:588)    at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332)    at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:543)    at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:149)    at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:124)    at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:196)    at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:110)    at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:79)    at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:353)    at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:180)    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)    at java.lang.reflect.Method.invoke(Method.java:597)    at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:629)    at org.eclipse.equinox.launcher.Main.basicRun(Main.java:584)    at org.eclipse.equinox.launcher.Main.run(Main.java:1438)

任何帮助都将受到欢迎！

编辑：我已经尝试过删除，放回可绘制对象，项目，…。清理项目，重新构建…我什至尝试删除并重新安装每个ADT组件

答案1

小编典典

正如@laato所建议的，我检查了我的drawable /
cadremenu文件。我在项目中复制/粘贴/覆盖了文件，然后一切正常！实际上，我所有其他资源都有相同的问题，例如我的资源文件夹已损坏或类似问题。

谢谢大家，希望有一天有人能在这里找到帮助

Android AVD Manager：无法创建新的设备定义(java.lang.NullPointerException)

我在Mac OS X 10.9.3上运行最新版本的 Android SDK.我以前没有安装Android SDK或任何其他Java开发环境,所以这可以被认为是一个全新的安装.

尝试使用AVD管理器创建新设备定义时,除了以下终端输出外,没有任何反应：

java.lang.NullPointerException
    at com.android.sdkuilib.internal.widgets.DeviceCreationDialog.okpressed(DeviceCreationDialog.java:916)
    at org.eclipse.jface.dialogs.Dialog.buttonpressed(Dialog.java:472)
    at org.eclipse.jface.dialogs.Dialog$2.widgetSelected(Dialog.java:624)
    at org.eclipse.swt.widgets.TypedListener.handleEvent(UnkNown Source)
    at org.eclipse.swt.widgets.EventTable.sendEvent(UnkNown Source)
    at org.eclipse.swt.widgets.display.sendEvent(UnkNown Source)
    at org.eclipse.swt.widgets.Widget.sendEvent(UnkNown Source)
    at org.eclipse.swt.widgets.Widget.sendEvent(UnkNown Source)
    at org.eclipse.swt.widgets.Widget.sendEvent(UnkNown Source)
    at org.eclipse.swt.widgets.Widget.notifyListeners(UnkNown Source)
    at org.eclipse.swt.widgets.display.runDeferredEvents(UnkNown Source)
    at org.eclipse.swt.widgets.display.readAnddispatch(UnkNown Source)
    at org.eclipse.jface.window.Window.runEventLoop(Window.java:825)
    at org.eclipse.jface.window.Window.open(Window.java:801)
    at com.android.sdkuilib.internal.repository.ui.DeviceManagerPage.onNewDevice(DeviceManagerPage.java:658)
    at com.android.sdkuilib.internal.repository.ui.DeviceManagerPage.access$100(DeviceManagerPage.java:97)
    at com.android.sdkuilib.internal.repository.ui.DeviceManagerPage$3.widgetSelected(DeviceManagerPage.java:215)
    at org.eclipse.swt.widgets.TypedListener.handleEvent(UnkNown Source)
    at org.eclipse.swt.widgets.EventTable.sendEvent(UnkNown Source)
    at org.eclipse.swt.widgets.display.sendEvent(UnkNown Source)
    at org.eclipse.swt.widgets.Widget.sendEvent(UnkNown Source)
    at org.eclipse.swt.widgets.Widget.sendEvent(UnkNown Source)
    at org.eclipse.swt.widgets.Widget.sendEvent(UnkNown Source)
    at org.eclipse.swt.widgets.Widget.notifyListeners(UnkNown Source)
    at org.eclipse.swt.widgets.display.runDeferredEvents(UnkNown Source)
    at org.eclipse.swt.widgets.display.readAnddispatch(UnkNown Source)
    at com.android.sdkuilib.internal.repository.ui.AvdManagerWindowImpl1.open(AvdManagerWindowImpl1.java:146)
    at com.android.sdkuilib.repository.AvdManagerWindow.open(AvdManagerWindow.java:94)
    at com.android.sdkmanager.Main.showAvdManagerWindow(Main.java:437)
    at com.android.sdkmanager.Main.doAction(Main.java:379)
    at com.android.sdkmanager.Main.run(Main.java:150)
    at com.android.sdkmanager.Main.main(Main.java:116)

这是窗口的屏幕截图：

我已经尝试运行AVD管理器,使用android avd和android sdk具有相同的结果.我能够根据通用设备定义创建一个新的AVD,就是这样.

我身边有什么问题,还是遇到某种错误？

解决方法

这似乎是框架中的一个错误,当我碰到它使用Eclipse Juno& ADT 23.0.2.错误报告如下.

https://code.google.com/p/android/issues/detail?id=73280

Android java.lang.RuntimeException：无法实例化活动ComponentInfo … java.lang.NullPointerException

出于某种原因,每次尝试启动我的应用程序时,我都会出现以下错误：

Unable to instantiate activity ComponentInfo{com.example.lifeahead/com.example.lifeahead.MainActivity}:java.lang.NullPointerException

我检查了清单文件,并添加了所有活动.

我启动应用程序时使用的唯一方法是：

private void logIn(){
    Button logIn = (Button) findViewById(R.id.login);
    logIn.setonClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {
            // Todo Auto-generated method stub
            Intent loginIntent = new Intent(MainActivity.this, HomeActivity.class);
            loginIntent.putExtra("cmUN", cmUN);
            loginIntent.putExtra("cmPW", cmPW);
            startActivity(loginIntent);
        }
    });
}

这是onCreate：

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    if (savedInstanceState == null) {
        getSupportFragmentManager().beginTransaction()
                .add(R.id.container, new PlaceholderFragment()).commit();
    }

    logIn();
}

完整日志：

/AndroidRuntime(1607): FATAL EXCEPTION: main
E/AndroidRuntime(1607): Process: com.example.lifeahead, PID: 1607
E/AndroidRuntime(1607): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.lifeahead/com.example.lifeahead.MainActivity}: java.lang.NullPointerException
E/AndroidRuntime(1607):     at android.app.ActivityThread.performlaunchActivity(ActivityThread.java:2121)
E/AndroidRuntime(1607):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
E/AndroidRuntime(1607):     at android.app.ActivityThread.access$800(ActivityThread.java:135)
E/AndroidRuntime(1607):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
E/AndroidRuntime(1607):     at android.os.Handler.dispatchMessage(Handler.java:102)
E/AndroidRuntime(1607):     at android.os.Looper.loop(Looper.java:136)
E/AndroidRuntime(1607):     at android.app.ActivityThread.main(ActivityThread.java:5017)
E/AndroidRuntime(1607):     at java.lang.reflect.Method.invokeNative(Native Method)
E/AndroidRuntime(1607):     at java.lang.reflect.Method.invoke(Method.java:515)
E/AndroidRuntime(1607):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
E/AndroidRuntime(1607):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
E/AndroidRuntime(1607):     at dalvik.system.NativeStart.main(Native Method)
E/AndroidRuntime(1607): Caused by: java.lang.NullPointerException
E/AndroidRuntime(1607):     at android.app.Activity.findViewById(Activity.java:1884)
E/AndroidRuntime(1607):     at com.example.lifeahead.MainActivity.<init>(MainActivity.java:22)
E/AndroidRuntime(1607):     at java.lang.class.newInstanceImpl(Native Method)
E/AndroidRuntime(1607):     at java.lang.class.newInstance(Class.java:1208)
E/AndroidRuntime(1607):     at android.app.Instrumentation.newActivity(Instrumentation.java:1061)
E/AndroidRuntime(1607):     at android.app.ActivityThread.performlaunchActivity(ActivityThread.java:2112)
E/AndroidRuntime(1607):     ... 11 more

我感谢所有帮助！

解决方法:

stacktrace告诉你

  Button logIn = (Button) findViewById(R.id.login);

findViewById返回的对象为null,因为您拥有的唯一方法是logIn(). findViewById返回null的唯一原因是因为您正在查找不属于当前活动的视图层次结构的视图

Android sdk：java.lang.NullPointerException：尝试调用虚方法

当我尝试在我的设备上调试应用程序并尝试在几个小时内摆脱它时,我收到此错误…并且无法弄清楚…如果有人能找到解决方案,那将是非常棒的,因为我想要尽快为我的应用发布新的更新..

07-05 22:45:02.550    2821-2821/davvarn.csgo_maps E/AndroidRuntime﹕ FATAL EXCEPTION: main
    Process: davvarn.csgo_maps,PID: 2821
    java.lang.RuntimeException: Unable to start activity ComponentInfo{davvarn.csgo_maps/davvarn.csgo_maps.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.ImageView.setimageDrawable(android.graphics.drawable.Drawable)' on a null object reference
            at android.app.ActivityThread.performlaunchActivity(ActivityThread.java:2356)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2418)
            at android.app.ActivityThread.access$900(ActivityThread.java:154)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1321)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:135)
            at android.app.ActivityThread.main(ActivityThread.java:5289)
            at java.lang.reflect.Method.invoke(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:372)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:904)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:699)
     Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.ImageView.setimageDrawable(android.graphics.drawable.Drawable)' on a null object reference
            at davvarn.csgo_maps.MainActivity.changeContent(MainActivity.java:176)
            at davvarn.csgo_maps.MainActivity.onCreate(MainActivity.java:115)
            at android.app.Activity.performCreate(Activity.java:5990)
            at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1106)
            at android.app.ActivityThread.performlaunchActivity(ActivityThread.java:2309)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2418)
at android.app.ActivityThread.access$900(ActivityThread.java:154)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1321)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5289)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:904)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:699)

我真的不知道如何粘贴MainActivity文件,因为我是Stackoverflow的新手.请让我知道如何,我会尝试.

解决方法

确保已初始化图像视图并使用XML中定义的正确ID.您可以像这样初始化ImageView：

ImageView imageView =(ImageView)findViewById(R.id.yourImageViewIDHere);

在onCreate调用setContentView之后,请执行此操作.

Android Studio：取消装箱“ xxx”可能会产生“ java.lang.NullPointerException”

我正在关注Android图书示例：

//Get the drink from the intent
int drinkIdd = (Integer)getIntent().getExtras().get(EXTRA_DRINKID);
Drink drink = Drink.drinks[drinkIdd];

该项目可以在Android Studio中运行，但在线上带有黄色警告：

int drinkIdd = (Integer)getIntent().getExtras().get(EXTRA_DRINKID);

与：

info: Unboxing of '(Integer)getIntent().getExtras().get(EXTRA_DRINKID)' may produce 'java.lang.NullPointerException'

根据我的理解，get(EXTRA_DRINKID)返回一个Object，然后（Integer）将其转换为int类型，以与满足int drinkIdd。

您能告诉我该信息的确切含义吗，对于初学者来说，您的回答将是值得的。
我可以这样写上限吗？使用（）将getIntent（）。getExtras（）。get（）打包为一个整体，因为它最终返回了一个对象，然后将其转换为int。
```
int drinkIdd = (Integer)(getIntent().getExtras().get(EXTRA_DRINKID));
```

关于Android XML文件java.lang.nullpointerexception和Android xml文件中为什么id属性会标红的介绍现已完结，谢谢您的耐心阅读，如果想了解更多关于Android AVD Manager：无法创建新的设备定义(java.lang.NullPointerException)、Android java.lang.RuntimeException：无法实例化活动ComponentInfo … java.lang.NullPointerException、Android sdk：java.lang.NullPointerException：尝试调用虚方法、Android Studio：取消装箱“ xxx”可能会产生“ java.lang.NullPointerException”的相关知识，请在本站寻找。

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