我有一个 Activity 类，其中我有一个静态标志，比方说

public static volatile flag = false;

然后在类里面，我启动了一个线程，它检查标志并做不同的事情。

我还有一个广播接收器，它将标志设置为 true 或 false。

虽然 volatile 会强制标志为最新值。但是我可以看到我的 broadcastreceiver 将静态标志设置为 true，但我的线程仍然将其设置为 false。

我是不是漏掉了一些基本的东西？任何帮助将不胜感激!

简化代码(更新)- 因此该标志应该在一分钟后更改为 true。但它从来没有。但来自广播接收器的消息显示它已更改为 true

TestappActivity.java:

package com.test;

import java.util.Calendar;

import android.app.Activity;
import android.app.AlarmManager;
import android.app.PendingIntent;
import android.content.Intent;
import android.os.Bundle;

public class TestappActivity extends Activity {
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        Intent intent0 = new Intent(this, TestService.class);
        this.startService(intent0);

        Intent intent = new Intent(this, TestReceiver.class);
        AlarmManager am = (AlarmManager) getSystemService(ALARM_SERVICE);
        PendingIntent sender = PendingIntent.getBroadcast(this,
                1, intent,
                PendingIntent.FLAG_UPDATE_CURRENT);
        Calendar slot = Calendar.getInstance();
        int min = slot.get(Calendar.MINUTE);
        slot.set(Calendar.MINUTE, min+1);
        am.set(AlarmManager.RTC_WAKEUP, slot.getTimeInMillis(), sender);
    }
}

测试服务.java:

package com.test;

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

public class TestService extends Service {

    private static final String TAG = "TestService";

    public static volatile boolean flag = false;

    private MyTopThread mTopThread;

    public TestService() {
    }

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


    @Override
    public void onCreate() {

    }

    @Override
    public void onDestroy() {

    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        protect();

        // We want this service to continue running until it is explicitly
        // stopped, so return sticky.
        return START_STICKY;
    }


    /**
     * Run protection
     * 
     */
    private void protect() {

        mTopThread = new MyTopThread();
        mTopThread.start();
    }


    private class MyTopThread extends Thread {

        @Override
        public void run() {
            while (true) {
                try {
                    Thread.sleep(150);
                    Log.d(TAG, "Flag is " + TestService.flag);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }

            }
        }

    }
}

测试接收者.java:

package com.test;

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.util.Log;

public class TestReceiver extends BroadcastReceiver {
    final static private String TAG = "TestReceiver";

    @Override
    public void onReceive(Context context, Intent intent) {
        Log.d(TAG, "onReceive is triggered ...");
        TestService.flag = true;
        Log.d(TAG, "flag is changed to " + TestService.flag);

    }
}

AndroidManifest.xml:

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.test"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk android:minSdkVersion="8" />

    <application
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name" >
        <activity
            android:name=".TestappActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

        <service android:name=".TestService" />

        <receiver
            android:name=".TestReceiver"
            android:process=":remote" >
        </receiver>
    </application>

</manifest>

最佳答案

我认为问题在于您在自己的进程中运行接收器。来自 android:process 的文档<receiver> 的属性:

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 broadcast receiver runs in that process.

我认为接收方正在修改 TestService.flag 的进程本地版本，而不是 TestService 使用的那个.尝试删除 android:process来自 <receiver> 的属性 list 中的标记。

关于Android volatile 不工作？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/8868167/