Android/Java ดู Activity Lifecycle

ดูเมธอดต่างๆของ Android Activity Lifecycle ด้วยการ log ออกมาดู

Method	Description
`onCreate`	called when activity is first created.
`onStart`	called when activity is becoming visible to the user.
`onResume`	called when activity will start interacting with the user.
`onPause`	called when activity is not visible to the user.
`onStop`	called when activity is no longer visible to the user.
`onRestart`	called after your activity is stopped, prior to start.
`onDestroy`	called before the activity is destroyed.

ไฟล์ที่เกี่ยวข้อง

MainActivity.java

MainActivity.java

package com.phaisarn.myapplication;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.util.Log;

public class MainActivity extends AppCompatActivity {

    String tag = "mylog";

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

        Log.v(tag, "[onCreate]");
    }

    // invoked when the activity may be temporarily destroyed, save the instance state here
    @Override
    public void onSaveInstanceState(Bundle outState) {
        // outState.putString(GAME_STATE_KEY, mGameState);
        // outState.putString(TEXT_VIEW_KEY, mTextView.getText());

        // call superclass to save any view hierarchy
        super.onSaveInstanceState(outState);
        Log.v(tag, "[onSaveInstanceState]");
    }

    // This callback is called only when there is a saved instance that is previously saved by using
    // onSaveInstanceState(). We restore some state in onCreate(), while we can optionally restore
    // other state here, possibly usable after onStart() has completed.
    // The savedInstanceState Bundle is same as the one used in onCreate().
    @Override
    public void onRestoreInstanceState(Bundle savedInstanceState) {
        super.onRestoreInstanceState(savedInstanceState);
        Log.v(tag, "[onRestoreInstanceState]");
    }

    @Override
    public void onStart() {
        super.onStart();
        Log.v(tag, "[onStart]");
    }

    @Override
    public void onResume() {
        super.onResume();
        Log.v(tag, "[onResume]");
    }

    @Override
    public void onPause() {
        super.onPause();
        Log.v(tag, "[onPause]");
    }

    @Override
    public void onStop() {
        super.onStop();
        Log.v(tag, "[onStop]");
    }

    @Override
    public void onRestart() {
        super.onRestart();
        Log.v(tag, "[onRestart]");
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        Log.v(tag, "[onDestroy]");
    }
}

การดู log ให้เปิด logcat ออกมาดู View > Tool Windows > Logcat

เลือกเครื่อง เลือก application เลือกระดับของ log เป็น Verbose แล้วพิมพ์ mylog เพื่อ filter log ให้เหลือน้อยลงจะได้ดูง่ายขึ้น

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