在 SharedPreference.Editor 上调用 putString 时，我的应用程序强制关闭

Question

The problem occurs when I call putString to SharedPreference. My program is first run through TileService which runs a ForegroundService then from ForegroundService opens an Activity and in this Activity I call putString to a SharedPreference.

How to make it work perfectly?

TileService

...
    @Override
    public void onClick()
    {
        super.onClick();
        Intent intent = new Intent(mContext,AdzanService.class);
        if(mTileEnabled)
            intent.setAction("STOP_SERVICE");
        else
            intent.setAction("START_SERVICE");
        startForegroundService(intent);
        mTileEnabled = !mTileEnabled;
    }
...

Service

...
    @Override
    public int onStartCommand(Intent intent, int flags, int startId)
    {
        if (intent.getAction().equals("STOP_SERVICE"))
        {
            stopForeground(true);
            stopSelf();
        }
...

Activity

...
    private void save(){
        mEditor.putString("setting_location",((EditText)findViewById(R.id.setting_location)).getText().toString());
        mEditor.putString("setting_times",((RadioButton)findViewById(((RadioGroup)findViewById(R.id.setting_times)).getCheckedRadioButtonId())).getTag().toString());
        mEditor.apply();
    }
...

Error

java.lang.RuntimeException: Unable to start service in.blackant.adzan.AdzanService@873299c with null: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String android.content.Intent.getAction()' on a null object reference
    at android.app.ActivityThread.handleServiceArgs(ActivityThread.java:3722)
    at android.app.ActivityThread.access$1600(ActivityThread.java:198)
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1686)
    at android.os.Handler.dispatchMessage(Handler.java:106)
    at android.os.Looper.loop(Looper.java:193)
    at android.app.ActivityThread.main(ActivityThread.java:6693)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:495)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:860)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String android.content.Intent.getAction()' on a null object reference
    at in.blackant.adzan.AdzanService.onStartCommand(AdzanService.java:97)
    at android.app.ActivityThread.handleServiceArgs(ActivityThread.java:3703)
    ... 8 more

Answer 1

As the error message states, the Intent in your service class is null when you call intent.getAction()

Intent is nullable here according to the docs

The Intent supplied to Context.startService(Intent), as given. This may be null if the service is being restarted after its process has gone away, and it had previously returned anything except START_STICKY_COMPATIBILITY.

Adding a null check before you check getAction() will fix the crash, but you might want to look into why your service is being restarted