第一行代码2.4 活动的生命周期

2.4.1 返回栈

2.4.2 活动状态

2.4.3 活动的生存周

2.4.4 体验活动的生命周期

main.activity

package com.example.activitylifecycletest;

import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;

public class MainActivity extends AppCompatActivity {
    public static  final String TAG ="MainActivity";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Button startNormalActivity = (Button) findViewById(R.id.start_normal_activity);
        Button startDialogActivity = (Button) findViewById(R.id.start_dialog_activity);
        startNormalActivity.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent intent = new Intent(MainActivity.this,NormalActivity.class);
                startActivity(intent);
            }
        });

        startDialogActivity.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent intent = new Intent(MainActivity.this,DialogActivity.class);
                startActivity(intent);
            }
        });
    }



    @Override
    protected void onStart() {
        super.onStart();
        Log.d(TAG, "onStart");
    }

    @Override
    protected void onResume() {
        super.onResume();
        Log.d(TAG,"onResume");
    }

    @Override
    protected void onPause() {
        super.onPause();
        Log.d(TAG,"onPause");
    }

    @Override
    protected void onStop() {
        super.onStop();
        Log.d(TAG,"onStop");
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        Log.d(TAG,"onDestroy");
    }

    @Override
    protected void onRestart() {
        super.onRestart();
        Log.d(TAG,"onRestart");
    }
}

2.4.5活动被回收了怎么办

  @Override
    public void onSaveInstanceState(Bundle outState, PersistableBundle outPersistentState) {
        super.onSaveInstanceState(outState, outPersistentState);
        String tempData = "Something you just typed";
        outState.putString("data_key",tempData);
    }

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

        if(savedInstanceState != null){
            String tempData = savedInstanceState.getString("data_key");
            Log.d(TAG,tempData);
        }
     }