当我在“拉伸到填充屏幕”到“缩放到填充屏幕”之间切换时,我在Wizerd创建的一个简单的 Android项目上获得了一个空指针异常,该项目由一个分开的过程中的服务创建.如果将服务放入与主活动相同的进程中,即未指定“android：process”属性,则不会发生此崩溃.虽然只有当我将“android：process”添加到我的测试服务的清单文件时才会发生.

例外是：

FATAL EXCEPTION: main

    java.lang.NullPointerException
      at android.view.WindowManagerImpl.reportNewConfiguration(WindowManagerImpl.java:427)
      at android.app.ActivityThread.handleUpdatePackageCompatibilityInfo(ActivityThread.java:2801)
      at android.app.ActivityThread.access$2700(ActivityThread.java:122)
      at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1151)
      at android.os.Handler.dispatchMessage(Handler.java:99)
      at android.os.Looper.loop(Looper.java:132)
      at android.app.ActivityThread.main(ActivityThread.java:4123)
      at java.lang.reflect.Method.invokeNative(Native Method)
      at java.lang.reflect.Method.invoke(Method.java:491)
      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:841)
      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:599)
      at dalvik.system.NativeStart.main(Native Method)

我的测试代码：

TestActivity.java(由Wizerd生成)

package com.test;

import android.app.Activity;

public class TestActivity extends Activity {
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        Intent intent = new Intent(this,TestService.class);
        startService(intent);
    }
}

TestService.java(大多数函数都是空的)

Package com.test;

import android.content.ComponentName;

public class TestService extends Service {
    private boolean m_connected = false;

    private ServiceConnection m_connInitService = new ServiceConnection() {
        public void onServiceConnection(ComponentName className,IBinder service) {
            m_connected = true;
        }

        public void onServicedisconnected(ComponentName className) {
        }
    };

    public static class TestServiceBinder extends Binder {
    }

    public IBinder onBind(Intent intent) {
        return new TestServiceBinder();
    }

    public void onDestroy() {
        super.onDestroy();
    }

    public int onStartCommand(Intent intent,int flags,int startId) {
        return 1;
    }
}

如果我在同一过程中没有服务或服务运行测试应用程序,屏幕兼容性开关将不会导致任何问题.但是,我不明白为什么服务会在屏幕兼容性切换期间导致系统异常.这是因为服务流程是非UI流程吗？哪个可能会触发Android核心代码中的错误？

我在文档中发现了以下内容：

android:process

If the name assigned to this attribute begins with a colon (‘:’),a
new process,private to the application,is created when it’s needed
and the service runs in that process. If the process name begins with
a lowercase character,the service will run in a global process of
that name,provided that it has permission to do so. This allows
components in different applications to share a process,reducing
resource usage.

因此,如果您指定以小写字母开头的进程名称,则应具有执行此操作的权限.但我不知道检查这些权限的位置.也许它们在WindowManagerImpl中被检查,它找不到这个全局进程,因此返回null.这只是一个假设.

我真的不知道我正在构建的 Android应用程序发生了什么.在它开发的某个时刻,我开始在模拟器中启动它,并显示消息“Foo stopped”.这是错误日志,如果有人可以帮助我：

07-05 21:13:30.063    7647-7647/root.fazerumsom E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: root.fazerumsom,PID: 7647
java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{root.fazerumsom/root.fazerumsom.MainActivity}: java.lang.NullPointerException
        at android.app.ActivityThread.performlaunchActivity(ActivityThread.java:2110)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2233)
        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:5001)
        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:785)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
        at dalvik.system.NativeStart.main(Native Method)
 Caused by: java.lang.NullPointerException
        at android.content.Contextwrapper.getResources(Contextwrapper.java:89)
        at android.view.ContextThemeWrapper.getResources(ContextThemeWrapper.java:78)
        at root.fazerumsom.MainActivity.<init>(MainActivity.java:31)
        at java.lang.class.newInstanceImpl(Native Method)
        at java.lang.class.newInstance(Class.java:1208)
        at android.app.Instrumentation.newActivity(Instrumentation.java:1061)
        at android.app.ActivityThread.performlaunchActivity(ActivityThread.java:2101)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2233)
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:5001)
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:785)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
at dalvik.system.NativeStart.main(Native Method)

您正在从字段初始值设定项中调用getResources().就像是

private String mStr = getResources().getString(...);

(或使用drawables或其他类型的资源).

这是无效的,因为尚未设置Context.在onCreate()方法中移动此赋值.