android四大组件之activity

activity生命周期

onCreate -> onStart -> onResume -> onPause -> onStop -> onDestroy

点击运行

onCreate -> onStart -> onResuem

点击home键

onPause -> onStop

再回到activity1界面

onRestart -> onStart -> onResume

点返回键

onPause -> onStop -> onDestroy

点击跳转 activity1-> activity2

onPause -> onCreate2 -> onStart2 -> onResume2 -> onStop

再按返回键

onPause2 -> onRestart -> onStart -> onResume -> onStop2 -> onDestroy2

两个activity的跳转

//方法一  .class  
Intent intent = new Intent(MainActivity.this,Activity2.class);
startActivity(intent);

//方法二   componentName
ComponentName cn = new ComponentName(this,Activity2.class);
Intent intent = new Intent();
intent.setComponentName(cn);
startActivity(intent);

//方法三   setClassName 
Intent intent = new Intent();
intent.setClassName("com.example.myapplication","com.example.myapplication.Activity2")
startActivity(intent);

方法四

<!先在manifest文件中配置好MainActivity的配置文件>  
<activity
            android:name=".MainActivity2"
            android:exported="false" >
            <intent-filter>
                <action android:name="MainActivity2"/>
                <category android:name="android.intent.category.DEFAULT"/>
            </intent-filter>
        </activity>

Intent intent = new Intent();
intent.setAction("MainActivity2");
startActivity(intent);