在OnResume之后立即调用OnPause

Question

EDIT* This issue is occurring while testing on a android device. This issue does not appear while testing on a emultor.

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I am starting a new activity and I see onPause is called right after onResume is called. If I look at log it goes to Idle after onResume. Therefore causing onPause right after onResume is called.

Caller activity - calling MainActivity on onClick via intent.

public class TestActivity extends AppCompatActivity implements View.OnClickListener{

    String TAG = "acr";
    Button testBtn;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_test);
        testBtn = (Button) findViewById(R.id.testBtn);
        testBtn.setOnClickListener(this);
    }

    @Override
    protected void onPause() {
        super.onPause();
        Log.i(TAG, "on pause called on TestActivity ");
    }

    @Override
    protected void onResume() {
        super.onResume();
        Log.i(TAG, "on resume called on  TestActivity ");
    }

    @Override
    public void onClick(View v) {
        switch(v.getId()){
            case R.id.testBtn:
                Intent mainIntent = new Intent(this, MainActivity.class);
                TestActivity.this.startActivity(mainIntent);
                break;
        }
    }
}

Activity that has bug

public class MainActivity extends AppCompatActivity{

    public static final String TAG = "acrx";


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }


    @Override
    protected void onPause() {
        super.onPause();
        Log.i(TAG, "on pause called on mainactivity");
    }

    @Override
    protected void onResume() {
        super.onResume();
        Log.i(TAG, "on resume Called on Main activity");
    }

    @Override
    protected void onStop() {
        super.onStop();
        Log.i(TAG, "on stop Called on Main activity");
    }
}

Log

12-06 23:24:19.751 22983-22983/com.example.m1alesis.smartcardreader I/acrx: on resume Called on Main activity
12-06 23:24:19.751 22983-22983/com.example.m1alesis.smartcardreader D/SecWifiDisplayUtil: Metadata value : SecSettings2
12-06 23:24:19.751 22983-22983/com.example.m1alesis.smartcardreader D/ViewRootImpl: #1 mView = com.android.internal.policy.PhoneWindow$DecorView{5ce8491 I.E...... R.....ID 0,0-0,0}
12-06 23:24:19.781 22983-23012/com.example.m1alesis.smartcardreader D/mali_winsys: EGLint new_window_surface(egl_winsys_display*, void*, EGLSurface, EGLConfig, egl_winsys_surface**, egl_color_buffer_format*, EGLBoolean) returns 0x3000,  [1440x2560]-format:1
12-06 23:24:19.811 22983-22983/com.example.m1alesis.smartcardreader W/DisplayListCanvas: DisplayListCanvas is started on unbinded RenderNode (without mOwningView)
12-06 23:24:19.831 22983-22983/com.example.m1alesis.smartcardreader D/ViewRootImpl: MSG_RESIZED_REPORT: ci=Rect(0, 96 - 0, 0) vi=Rect(0, 96 - 0, 0) or=1
12-06 23:24:19.871 22983-23012/com.example.m1alesis.smartcardreader D/OpenGLRenderer: endAllActiveAnimators on 0x7f9c17ec00 (RippleDrawable) with handle 0x7f9ccc8b60
12-06 23:24:19.871 22983-22983/com.example.m1alesis.smartcardreader I/Timeline: Timeline: Activity_idle id: android.os.BinderProxy@fa2f707 time:376798424
12-06 23:24:20.131 22983-22983/com.example.m1alesis.smartcardreader V/ActivityThread: updateVisibility : ActivityRecord{e78cff6 token=android.os.BinderProxy@a67fd36 {com.example.m1alesis.smartcardreader/com.example.m1alesis.smartcardreader.TestActivity}} show : false
12-06 23:24:31.561 22983-22983/com.example.m1alesis.smartcardreader I/acrx: on pause called on mainactivity
12-06 23:24:31.701 22983-22983/com.example.m1alesis.smartcardreader I/acrx: on resume Called on Main activity
12-06 23:24:31.721 22983-22983/com.example.m1alesis.smartcardreader I/Timeline: Timeline: Activity_idle id: android.os.BinderProxy@fa2f707 time:376810271

Answer 1

I tried it in my test activity and I did not get your problem. I had only one button on my MainActivity and my TestActivity.

I have found something here: Pausing and Resuming an Activity .

This is the interesting part:

Note: When the system calls your activity's onPause() method, the system may be signaling that the activity will be paused for a moment and the user may return focus to your activity, or that the app is running in multi-window mode. However, this method call may also be the first indication that the user is leaving your activity.

Answer 2

I had the same issue and for me it is related to the activity starting up and the screen not being on - I only saw it after I had the screen off (eg after touching the power button and then home to resume again).

This is a behaviour that others have seen also - I found this question and answer has useful references: OnPause and OnStop() called immediately after starting activity

The key quote that helped me understand the behaviour was:

Keep in mind that onResume is not the best indicator that your activity is visible to the user; a system window such as the keyguard may be in front. Use onWindowFocusChanged(boolean) to know for certain that your activity is visible to the user