Question

MyService类包含静态字符串

package com.suprabhatam.alarm;

import android.app.Service;
import android.content.Intent;
import android.media.MediaPlayer;
import android.os.IBinder;
import android.util.Log;

import java.text.SimpleDateFormat;
import java.util.Calendar;

public class MyService extends Service {
    private static final String TAG = "MyService";
    static public MediaPlayer mp;
    final static public String start_pause_stop_audio = "start_pause_stop_audio";
    final static public String start_audio = "start_audio";
    final static public String pause_audio = "pause_audio";
    final static public String stop_audio = "stop_audio";

    @Override
    public int onStartCommand (Intent intent, int flags, int startId) {
        Calendar cal = Calendar.getInstance();
        cal.getTime();
        SimpleDateFormat sdf = new SimpleDateFormat("HH:mm:ss");
        Log.d(TAG, sdf.format(cal.getTime()));

        if (mp == null) {
            mp = MediaPlayer.create(this, R.raw.venkateshwara_suprabhatam);
        }

        final String s_s_audio = intent.getStringExtra(MyService.start_pause_stop_audio);
        Log.d(TAG, "onStartCommand: " + s_s_audio);
        if (s_s_audio.equals(start_audio)) {
            if (!mp.isPlaying()) {
                mp.start();
            } else {
                Log.d(TAG, "already playing");
            }
        } else if (s_s_audio.equals(pause_audio)) {
            mp.pause();
        } else if (s_s_audio.equals(stop_audio)) {
            mp.seekTo(0);
            mp.pause();
        } else {
            Log.d(TAG, "UNKNOWN: " + s_s_audio);
        }

        return START_STICKY;
    }

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

    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }
}

崩溃应用程序，adb输出上显示以下消息。

ANRAppManager﹕ !!! It is not under singleton mode, U can't use it. !!!

只有当应用程序不在内存中时才会发生崩溃（kill）并且 MyReceiver 会尝试访问静态字符串。

在创建对象之前，静态字符串看起来无效。在C ++中，静态字符串转到数据段并在应用程序启动时有效，java中的规则是不同的吗？

更新1：添加logcat消息

01-20 21:53:32.849    2396-2396/com.suprabhatam.alarm D/jdwp﹕ sendBufferedRequest : len=0x45
01-20 21:53:32.854    2396-2396/com.suprabhatam.alarm W/asset﹕ AssetManager-->addDefaultAssets CIP path not exsit!
01-20 21:53:32.875    2396-2396/com.suprabhatam.alarm D/dalvikvm﹕ open_cached_dex_file : /data/app/com.suprabhatam.alarm-1.apk /data/dalvik-cache/data@app@com.suprabhatam.alarm-1.apk@classes.dex
01-20 21:53:32.897    2396-2396/com.suprabhatam.alarm D/MyService﹕ 21:53:32
01-20 21:53:32.959    2396-2396/com.suprabhatam.alarm D/MediaPlayer﹕ Don't notify duration to com.suprabhatam.alarm!
01-20 21:53:32.983    2396-2396/com.suprabhatam.alarm D/AndroidRuntime﹕ Shutting down VM
01-20 21:53:32.983    2396-2396/com.suprabhatam.alarm W/dalvikvm﹕ threadid=1: thread exiting with uncaught exception (group=0x41bea9a8)
01-20 21:53:32.984    2396-2396/com.suprabhatam.alarm W/dalvikvm﹕ threadid=1: uncaught exception occurred
01-20 21:53:32.984    2396-2396/com.suprabhatam.alarm W/System.err﹕ java.lang.RuntimeException: Unable to start service com.suprabhatam.alarm.MyService@421b4720 with null: java.lang.NullPointerException
01-20 21:53:32.984    2396-2396/com.suprabhatam.alarm W/System.err﹕ at android.app.ActivityThread.handleServiceArgs(ActivityThread.java:2867)
01-20 21:53:32.984    2396-2396/com.suprabhatam.alarm W/System.err﹕ at android.app.ActivityThread.access$1900(ActivityThread.java:165)
01-20 21:53:32.984    2396-2396/com.suprabhatam.alarm W/System.err﹕ at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1470)
01-20 21:53:32.984    2396-2396/com.suprabhatam.alarm W/System.err﹕ at android.os.Handler.dispatchMessage(Handler.java:107)
01-20 21:53:32.984    2396-2396/com.suprabhatam.alarm W/System.err﹕ at android.os.Looper.loop(Looper.java:194)
01-20 21:53:32.984    2396-2396/com.suprabhatam.alarm W/System.err﹕ at android.app.ActivityThread.main(ActivityThread.java:5391)
01-20 21:53:32.985    2396-2396/com.suprabhatam.alarm W/System.err﹕ at java.lang.reflect.Method.invokeNative(Native Method)
01-20 21:53:32.985    2396-2396/com.suprabhatam.alarm W/System.err﹕ at java.lang.reflect.Method.invoke(Method.java:525)
01-20 21:53:32.985    2396-2396/com.suprabhatam.alarm W/System.err﹕ at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:833)
01-20 21:53:32.985    2396-2396/com.suprabhatam.alarm W/System.err﹕ at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:600)
01-20 21:53:32.985    2396-2396/com.suprabhatam.alarm W/System.err﹕ at dalvik.system.NativeStart.main(Native Method)
01-20 21:53:32.985    2396-2396/com.suprabhatam.alarm W/System.err﹕ Caused by: java.lang.NullPointerException
01-20 21:53:32.986    2396-2396/com.suprabhatam.alarm W/System.err﹕ at com.suprabhatam.alarm.MyService.onStartCommand(MyService.java:34)
01-20 21:53:32.986    2396-2396/com.suprabhatam.alarm W/System.err﹕ at android.app.ActivityThread.handleServiceArgs(ActivityThread.java:2850)
01-20 21:53:32.986    2396-2396/com.suprabhatam.alarm W/System.err﹕ ... 10 more
01-20 21:53:32.986    2396-2396/com.suprabhatam.alarm W/dalvikvm﹕ threadid=1: calling UncaughtExceptionHandler
01-20 21:53:32.987    2396-2396/com.suprabhatam.alarm E/AndroidRuntime﹕ FATAL EXCEPTION: main
    java.lang.RuntimeException: Unable to start service com.suprabhatam.alarm.MyService@421b4720 with null: java.lang.NullPointerException
            at android.app.ActivityThread.handleServiceArgs(ActivityThread.java:2867)
            at android.app.ActivityThread.access$1900(ActivityThread.java:165)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1470)
            at android.os.Handler.dispatchMessage(Handler.java:107)
            at android.os.Looper.loop(Looper.java:194)
            at android.app.ActivityThread.main(ActivityThread.java:5391)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:525)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:833)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:600)
            at dalvik.system.NativeStart.main(Native Method)
     Caused by: java.lang.NullPointerException
            at com.suprabhatam.alarm.MyService.onStartCommand(MyService.java:34)
            at android.app.ActivityThread.handleServiceArgs(ActivityThread.java:2850)
            at android.app.ActivityThread.access$1900(ActivityThread.java:165)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1470)
            at android.os.Handler.dispatchMessage(Handler.java:107)
            at android.os.Looper.loop(Looper.java:194)
            at android.app.ActivityThread.main(ActivityThread.java:5391)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:525)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:833)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:600)
            at dalvik.system.NativeStart.main(Native Method)

更新2秒崩溃

01-20 21:56:23.332    2793-2799/com.suprabhatam.alarm D/jdwp﹕ handlePacket : cmd=0x1, cmdSet=0xC7, len=0x13, id=0x400000DF, flags=0x0, dataLen=0x8
01-20 21:56:42.336    2793-2805/com.suprabhatam.alarm D/ANRAppManager﹕ !!! It is not under singleton mode, U can't use it. !!!
01-20 21:57:33.091    2793-2793/com.suprabhatam.alarm I/Process﹕ Sending signal. PID: 2793 SIG: 9
01-20 21:57:38.252    3008-3008/com.suprabhatam.alarm D/MediaPlayer﹕ Don't notify duration to com.suprabhatam.alarm!
01-20 21:57:38.260    3008-3008/com.suprabhatam.alarm D/AndroidRuntime﹕ Shutting down VM
01-20 21:57:38.260    3008-3008/com.suprabhatam.alarm W/dalvikvm﹕ threadid=1: thread exiting with uncaught exception (group=0x41bea9a8)
01-20 21:57:38.260    3008-3008/com.suprabhatam.alarm W/dalvikvm﹕ threadid=1: uncaught exception occurred
01-20 21:57:38.260    3008-3008/com.suprabhatam.alarm W/System.err﹕ java.lang.RuntimeException: Unable to start service com.suprabhatam.alarm.MyService@421af568 with null: java.lang.NullPointerException
01-20 21:57:38.260    3008-3008/com.suprabhatam.alarm W/System.err﹕ at android.app.ActivityThread.handleServiceArgs(ActivityThread.java:2867)
01-20 21:57:38.260    3008-3008/com.suprabhatam.alarm W/System.err﹕ at android.app.ActivityThread.access$1900(ActivityThread.java:165)
01-20 21:57:38.260    3008-3008/com.suprabhatam.alarm W/System.err﹕ at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1470)
01-20 21:57:38.260    3008-3008/com.suprabhatam.alarm W/System.err﹕ at android.os.Handler.dispatchMessage(Handler.java:107)
01-20 21:57:38.260    3008-3008/com.suprabhatam.alarm W/System.err﹕ at android.os.Looper.loop(Looper.java:194)
01-20 21:57:38.261    3008-3008/com.suprabhatam.alarm W/System.err﹕ at android.app.ActivityThread.main(ActivityThread.java:5391)
01-20 21:57:38.261    3008-3008/com.suprabhatam.alarm W/System.err﹕ at java.lang.reflect.Method.invokeNative(Native Method)
01-20 21:57:38.261    3008-3008/com.suprabhatam.alarm W/System.err﹕ at java.lang.reflect.Method.invoke(Method.java:525)
01-20 21:57:38.261    3008-3008/com.suprabhatam.alarm W/System.err﹕ at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:833)
01-20 21:57:38.261    3008-3008/com.suprabhatam.alarm W/System.err﹕ at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:600)
01-20 21:57:38.261    3008-3008/com.suprabhatam.alarm W/System.err﹕ at dalvik.system.NativeStart.main(Native Method)
01-20 21:57:38.261    3008-3008/com.suprabhatam.alarm W/System.err﹕ Caused by: java.lang.NullPointerException
01-20 21:57:38.261    3008-3008/com.suprabhatam.alarm W/System.err﹕ at com.suprabhatam.alarm.MyService.onStartCommand(MyService.java:34)
01-20 21:57:38.261    3008-3008/com.suprabhatam.alarm W/System.err﹕ at android.app.ActivityThread.handleServiceArgs(ActivityThread.java:2850)
01-20 21:57:38.261    3008-3008/com.suprabhatam.alarm W/System.err﹕ ... 10 more
01-20 21:57:38.261    3008-3008/com.suprabhatam.alarm W/dalvikvm﹕ threadid=1: calling UncaughtExceptionHandler
01-20 21:57:38.262    3008-3008/com.suprabhatam.alarm E/AndroidRuntime﹕ FATAL EXCEPTION: main
    java.lang.RuntimeException: Unable to start service com.suprabhatam.alarm.MyService@421af568 with null: java.lang.NullPointerException
            at android.app.ActivityThread.handleServiceArgs(ActivityThread.java:2867)
            at android.app.ActivityThread.access$1900(ActivityThread.java:165)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1470)
            at android.os.Handler.dispatchMessage(Handler.java:107)
            at android.os.Looper.loop(Looper.java:194)
            at android.app.ActivityThread.main(ActivityThread.java:5391)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:525)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:833)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:600)
            at dalvik.system.NativeStart.main(Native Method)
     Caused by: java.lang.NullPointerException
            at com.suprabhatam.alarm.MyService.onStartCommand(MyService.java:34)
            at android.app.ActivityThread.handleServiceArgs(ActivityThread.java:2850)
            at android.app.ActivityThread.access$1900(ActivityThread.java:165)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1470)
            at android.os.Handler.dispatchMessage(Handler.java:107)
            at android.os.Looper.loop(Looper.java:194)
            at android.app.ActivityThread.main(ActivityThread.java:5391)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:525)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:833)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:600)
            at dalvik.system.NativeStart.main(Native Method)
01-20 21:57:58.221    3008-3020/com.suprabhatam.alarm D/ANRAppManager﹕ !!! It is not under singleton mode, U can't use it. !!!
01-20 22:02:38.277    3008-3008/com.suprabhatam.alarm I/Process﹕ Sending signal. PID: 3008 SIG: 9

更新了3个崩溃位置

崩溃发生在MyService.java的第32行

final String s_s_audio = intent.getStringExtra（MyService.start_pause_stop_audio）

01-20 22：22：42.230 6257-6257 / com.suprabhatam.alarm E / MyService：exception 显示java.lang.NullPointerException at com.suprabhatam.alarm.MyService.onStartCommand（MyService.java:32）在android.app.ActivityThread.handleServiceArgs（ActivityThread.java:2850）在android.app.ActivityThread.access $ 1900（ActivityThread.java:165）

问题似乎与intent.getStringExtra（）方法

有关

广播接收器发送以下事件。

Intent myIntent = new Intent(context, MyService.class);
myIntent.putExtra(MyService.start_pause_stop_audio, MyService.start_audio);
context.startService(myIntent);

如何调试此问题。

Answer 1

在执行任何操作之前，您应该检查onStartCommand()中收到的意图参数是否为空。 这是因为如果服务被系统杀死然后重新启动，Intent可以为null，并且您不要求重新发送原始意图。

请仔细查看here并最终将onStartCommand()的结果值更改为START_REDELIVER_INTENT，

Answer 2

更好的解决方案是从一个公共类中获取字符串，例如YourConstants.java和此类中的所有成员： public static final String;

然后当你需要它们时，无论你的项目在哪里打电话 YourConstants.NAME_OFF_YOUR_VARIABLE，你不会有这个问题。

我总是使用Constants类作为我的公共静态最终变量。

使用＆＃34;空指针异常＆＃34;访问静态字符串崩溃

2 个答案: