當前版本：
compileSdkVersion 29
implementation 'androidx.appcompat:appcompat:1.2.0'

第一步：創(chuàng)建Activity繼承AppCompatActivity類。

public class LifeCycleActivity extends AppCompatActivity {
 @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_life_cycle);

    }
}

第二步：定義一個類MyLifeCycleObserver，實現(xiàn)LifecycleObserver接口。

在MyLifeCycleObserver中定義方法，加上@OnLifecycleEvent注解

import android.util.Log;

import androidx.lifecycle.Lifecycle;
import androidx.lifecycle.LifecycleObserver;
import androidx.lifecycle.OnLifecycleEvent;
public class MyLifeCycleObserver implements LifecycleObserver {
    private static final String TAG = MyLifeCycleObserver.class.getSimpleName();

    @OnLifecycleEvent(Lifecycle.Event.ON_CREATE)
    public void onCreate() {
        Log.e(TAG, "onCreate");
    }

    @OnLifecycleEvent(Lifecycle.Event.ON_START)
    public void onStart() {
        Log.e(TAG, "onStart");
    }

    @OnLifecycleEvent(Lifecycle.Event.ON_RESUME)
    public void onResume() {
        Log.e(TAG, "onResume");
    }

    @OnLifecycleEvent(Lifecycle.Event.ON_PAUSE)
    public void onPause() {
        Log.e(TAG, "onPause");
    }

    @OnLifecycleEvent(Lifecycle.Event.ON_STOP)
    public void onStop() {
        Log.e(TAG, "onStop");
    }

    @OnLifecycleEvent(Lifecycle.Event.ON_DESTROY)
    public void onDestory() {
        Log.e(TAG, "onDestory");
    }

    @OnLifecycleEvent(Lifecycle.Event.ON_ANY)
    public void onAny() {
        Log.e(TAG, "onAny");
    }

}

第三步：在Activity中，getLifecycle().addObserver(new MyLifeCycleObserver());

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        Log.e(TAG, "onCreate    enable:"+enable());
        setContentView(R.layout.activity_life_cycle);
        getLifecycle().addObserver(new MyLifeCycleObserver());
    }

MyLifeCycleObserver 由創(chuàng)建到銷毀，其生命周期方法的會被MyLifeCycleObserver觀察到，并依次執(zhí)行其生命周期相關聯(lián)的方法。
運行結果如下

2020-11-19 10:11:34.793 20430-20430/com.example.jetpack E/LifeCycleActivity: onCreate
2020-11-19 10:11:34.815 20430-20430/com.example.jetpack E/MyLifeCycleObserver: onCreate
2020-11-19 10:11:34.815 20430-20430/com.example.jetpack E/MyLifeCycleObserver: onAny

2020-11-19 10:11:34.818 20430-20430/com.example.jetpack E/LifeCycleActivity: onStart
2020-11-19 10:11:34.818 20430-20430/com.example.jetpack E/MyLifeCycleObserver: onStart
2020-11-19 10:11:34.818 20430-20430/com.example.jetpack E/MyLifeCycleObserver: onAny

2020-11-19 10:11:34.818 20430-20430/com.example.jetpack E/LifeCycleActivity: onResume
2020-11-19 10:11:34.818 20430-20430/com.example.jetpack E/MyLifeCycleObserver: onResume
2020-11-19 10:11:34.819 20430-20430/com.example.jetpack E/MyLifeCycleObserver: onAny

2020-11-19 10:11:38.678 20430-20430/com.example.jetpack E/MyLifeCycleObserver: onPause
2020-11-19 10:11:38.678 20430-20430/com.example.jetpack E/MyLifeCycleObserver: onAny
2020-11-19 10:11:38.678 20430-20430/com.example.jetpack E/LifeCycleActivity: onPause

2020-11-19 10:11:39.278 20430-20430/com.example.jetpack E/MyLifeCycleObserver: onStop
2020-11-19 10:11:39.278 20430-20430/com.example.jetpack E/MyLifeCycleObserver: onAny
2020-11-19 10:11:39.278 20430-20430/com.example.jetpack E/LifeCycleActivity: onStop

2020-11-19 10:11:39.279 20430-20430/com.example.jetpack E/MyLifeCycleObserver: onDestory
2020-11-19 10:11:39.279 20430-20430/com.example.jetpack E/MyLifeCycleObserver: onAny
2020-11-19 10:11:39.280 20430-20430/com.example.jetpack E/LifeCycleActivity: onDestroy

需要注意的是：

當activity生命周期方法觸發(fā)時，會同時回調到這里
需要注意的是：
1.onCreate、onStart和onResume三個方法，會在對應的Activity方法執(zhí)行完之后執(zhí)行，
而onPause、onStop和onDestory 三個方法，會在對應的Activity方法之前執(zhí)行。
2.onAny方法會在LifecycleObserver的每個生命周期方法執(zhí)行之后調用。