Android process killer

Maybe you can help.

Is it possible t开发者_开发问答o get list of all Processes which are running in the Android system, and kill some of them? I know that there are some applications (task managers), but I would like to write my own, simple application.

I would like to write simple task manager, just list of all processes and button which will kill some of them.

Could you just write some Java methods which I can call in order to get list of process, and method for killing them. Or just give me some advice's.

Killing apps/services in Android is generally a really bad idea. Whilst it is possible to write task killer apps, it shouldn't be encouraged for anything outside of development/debugging purposes.

Task management is the responsibility of the Android O/S, the tasks you can see are not processes (in the sense of the processes you see in the Windows task manager for example), in fact, they only have a process when Android tells them they can have one.

Apps are regularly broken by these task management tools, as they often fail to recover from the forced termination, particularly if they were busy writing to a file or using another resource when they were killed. It also puts the handset users into a false expectation that the apps listed are actually RUNNING on their phone, which they are often not. This is explained in the [ActivityManager docs][1]:

Information you can retrieve about a particular task that is currently "running" in the system. Note that a running task does not mean the given task actual has a process it is actively running in; it simply means that the user has gone to it and never closed it, but currently the system may have killed its process and is only holding on to its last state in order to restart it when the user returns.

When you see the list of running apps in apps like TaskKiller or Quick System Info, many of them are not actually running, they are just in a suspended state. These apps are not consuming system resources because Android has decided to stop them until they are needed again. However, when you kill them, you don't give them time to shut down cleanly, and when you try to launch them next time you can be presented with an unfriendly force close dialog. I have seen apps break completely, with even a re-install being ineffective, because they are trying to read a corrupted file on the SD card, or they use unofficial API calls.

In short, friends don't let friends use task killers in Android.

Anyway, to answer your question, the ActivityManageris what most of these apps use to list activities that are in running/suspended state.

freetaskmanager is an example of one of these task managers in use.

    // Get currently running application processes
    List<ActivityManager.RunningAppProcessInfo> list = servMng.getRunningAppProcesses();
    if(list != null){
     for(int i=0;i<list.size();++i){
      if("com.android.email".matches(list.get(i).processName)){
       int pid = android.os.Process.getUidForName("com.android.email");
             android.os.Process.killProcess(pid);
      }else{
       mTextVIew.append(list.get(i).processName + "\n");
      }
     }
    }


    /*
    // Get currently running service
    List<ActivityManager.RunningServiceInfo> list = servMng.getRunningServices(1024);
    if(list != null){
     for(int i=0;i<list.size();++i){
      mTextVIew.append(list.get(i).service.getClassName() + "\n");
     }
    }
    */

    /*
    // Get currently running tasks
    List<ActivityManager.RunningTaskInfo> list = servMng.getRunningTasks(1024);
    if(list != null){
     for(int i=0;i<list.size();++i){
      mTextVIew.append(list.get(i).toString() + "\n");
     }
    }
    */

Exiting an Android App via Java is tricky to say the least. Killing the app via the Process Object interface is generally considered bad form for all the reasons listed above, I wont rehash them, but I don't feel that the published discouragements are meant to stop you from doing it all together, they just make you aware of possible caveats. Here's the catch, Android has to keep track of Activities and load/run order because the devices have a back button...so you dutifully call finish() or finishFromChild(childActivity)and when the user exits the app, there's a previous activity from your app, happily ignoring your code that asked it exit.

Sometimes, you just have to kill the app. So...before committing this digital process kill, you have to do a little planning. Make sure the user won't be killing any file I/O or network communication vital to your app. My strategy for this was to front load my Activities to do all the heavy lifting on or near to the load events.

Also, I always prompt the user before they exit, a desktop application UI convention that translates well here.

The above code misses the mark by calling "getUidForName"...

This example captures the Android Native back button event from the hardware back button and prompts the user "do you really want to leave my app" and if the user selects "yes" it kills the App.

    @Override 
public boolean onKeyDown(int keyCode, KeyEvent event) {
    //Handle the back button
    if(keyCode == KeyEvent.KEYCODE_BACK) {
        //Ask the user if they want to quit
        new AlertDialog.Builder(this)
        .setIcon(android.R.drawable.exclamationpoint)
        .setTitle("Exit?")
        .setMessage("You are about to exit the Application. " + 
                     "Do you really want to exit?")
        .setPositiveButton("Yes", new DialogInterface.OnClickListener() {
             @Override
            public void onClick(DialogInterface dialog, int which) {
                //Stop the activity
                 //maintenancetabs.this.finish();
                 int pid = android.os.Process.myPid();
                 android.os.Process.killProcess(pid);
                }
         })
        .setNegativeButton("No", null)
        .show();
         return true;
    }     else {
        return super.onKeyDown(keyCode, event);
    }
 }