Fragment生命周期及add、replace、remove、hide&show方法分析


轉載自https://blog.csdn.net/u014699958/article/details/52996143
項目有一個Activity類和3個Fragment類。Activity 中放置3個按鈕(實質TextView)可以切換到不同的Fragment上。下面將給出Activity 和Fragment的代碼和layout。

1-1 Fragment1

public class Fragment1 extends Fragment {
final String TAG = " test Fragment1";

public Fragment1() {
// Required empty public constructor
}

@Override
public void onAttach(Context context) {
super.onAttach(context);
Log.d(TAG,"onAttach");
}

@Override
public void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Log.d(TAG,"onCreate");
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment1_layout, null);
Log.d(TAG,"onCreateView");
return view;
}

@Override
public void onActivityCreated(@Nullable Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
Log.d(TAG,"onActivityCreated");
}

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

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

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

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

@Override
public void onDestroyView() {
super.onDestroyView();
Log.d(TAG,"onDestroyView");
}

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

@Override
public void onDetach() {
super.onDetach();
Log.d(TAG,"onDetach");
}
}

1-2 fragment1_layout.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#888"
android:gravity="center">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textSize="30sp"
android:text="Fragment1"/>
</LinearLayout>

2-1 Fragment2

public class Fragment2 extends Fragment {
final String TAG = " test Fragment2";

public Fragment2() {
// Required empty public constructor
}

@Override
public void onAttach(Context context) {
super.onAttach(context);
Log.d(TAG,"onAttach");
}

@Override
public void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Log.d(TAG,"onCreate");
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment2_layout, null);
Log.d(TAG,"onCreateView");
return view;
}

@Override
public void onActivityCreated(@Nullable Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
Log.d(TAG,"onActivityCreated");
}

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

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

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

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

@Override
public void onDestroyView() {
super.onDestroyView();
Log.d(TAG,"onDestroyView");
}

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

@Override
public void onDetach() {
super.onDetach();
Log.d(TAG,"onDetach");
}
}

2-2 fragment2_layout.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#888"
android:gravity="center">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textSize="30sp"
android:text="Fragment2"/>
</LinearLayout>

3-1 Fragment3

public class Fragment3 extends Fragment {
final String TAG = " test Fragment3";

public Fragment3() {
// Required empty public constructor
}

@Override
public void onAttach(Context context) {
super.onAttach(context);
Log.d(TAG,"onAttach");
}

@Override
public void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Log.d(TAG,"onCreate");
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment3_layout, null);
Log.d(TAG,"onCreateView");
return view;
}

@Override
public void onActivityCreated(@Nullable Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
Log.d(TAG,"onActivityCreated");
}

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

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

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

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

@Override
public void onDestroyView() {
super.onDestroyView();
Log.d(TAG,"onDestroyView");
}

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

@Override
public void onDetach() {
super.onDetach();
Log.d(TAG,"onDetach");
}
}


3-2 fragment3_layout.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#888"
android:gravity="center">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textSize="30sp"
android:text="Fragment3"/>
</LinearLayout>

4-1 MainActivity

public class MainActivity extends Activity{
final String TAG = " test MainActivity";

TextView mFragment1Tv ;
TextView mFragment2Tv ;
TextView mFragment3Tv ;

FrameLayout mainll ;

FragmentManager manager ;
FragmentTransaction transaction;

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

initView();
initListener();
initData();

Log.d(TAG,"onCreate");
}

private void initListener() {
mFragment1Tv.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Fragment1 fragment1= new Fragment1();
transaction = manager.beginTransaction();
transaction.add(R.id.main_ll, fragment1,"1");
transaction.commit();
}
});
mFragment2Tv.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Fragment2 fragment2= new Fragment2();
transaction = manager.beginTransaction();
transaction.add(R.id.main_ll, fragment2,"2");
transaction.commit();
}
});
mFragment3Tv.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Fragment3 fragment3= new Fragment3();
transaction = manager.beginTransaction();
transaction.add(R.id.main_ll, fragment3,"3");
transaction.commit();
}
});
}

private void initData() {
manager = getFragmentManager();
}

private void initView() {
mFragment1Tv = (TextView) findViewById(R.id.fragment1_tv);
mFragment2Tv = (TextView) findViewById(R.id.fragment2_tv);
mFragment3Tv = (TextView) findViewById(R.id.fragment3_tv);
mainll = (FrameLayout) findViewById(R.id.main_ll);

}

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

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

@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");
}
}


4-2 activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/activity_main"
android:layout_width="match_parent"
android:layout_height="match_parent">

<LinearLayout
android:id="@+id/index"
android:layout_width="match_parent"
android:layout_height="40dp"
android:orientation="horizontal">

<TextView
android:id="@+id/fragment1_tv"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_margin="5dp"
android:background="#bbb"
android:text="Fragment1"
android:textSize="22sp" />

<TextView
android:id="@+id/fragment2_tv"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_margin="5dp"
android:background="#bbb"
android:text="Fragment2"
android:textSize="22sp" />

<TextView
android:id="@+id/fragment3_tv"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_margin="5dp"
android:background="#bbb"
android:text="Fragment3"
android:textSize="22sp" />
</LinearLayout>
<View
android:layout_below="@id/index"
android:layout_width="match_parent"
android:layout_height="1dp"
android:background="#aaa"/>

<LinearLayout
android:id="@+id/main_ll"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:layout_alignParentBottom="true"
android:layout_alignParentStart="true">
</LinearLayout>


</RelativeLayout>

5 測試生命周期
(一) add 方法分析
1.啟動app,log如圖:

 

 

 


界面如下:

 

 

 


2.點擊Fragment1,log如下:

 

 

 


界面如下:

 

 

 


3點擊fragment2 log如下: (這里並沒有觸發fragment1的生命周期)

 

 

 


界面如下:

 

 

 


4點擊fragment3 log如下:

 

 

 


界面如下:

 

 

 


5 在此時分為兩次不同的操作:

5-1 測試返回
操作:點擊返回鍵,此時應用已經退出。log如下:

 

 

 


5-2 home鍵測試
操作:(1)點擊home鍵,app退到后台,log如下:

 

 

 


(2)點擊應用圖標重新打開app,log如下:

 

 

 

 

6 回退棧測試
再回到5-1 ,如果想要點擊返回鍵回到上一個Fragment的話,那么就需要加入到會退棧。
修改 MainActivity 的方法initListener如下:

private void initListener() {
mFragment1Tv.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Fragment1 fragment1= new Fragment1();
transaction = manager.beginTransaction();
transaction.add(R.id.main_ll, fragment1,"1");
transaction.addToBackStack(null);
transaction.commit();
}
});
mFragment2Tv.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Fragment2 fragment2= new Fragment2();
transaction = manager.beginTransaction();
transaction.add(R.id.main_ll, fragment2,"2");
transaction.addToBackStack(null);
transaction.commit();
}
});
mFragment3Tv.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Fragment3 fragment3= new Fragment3();
transaction = manager.beginTransaction();
transaction.add(R.id.main_ll, fragment3,"3");
transaction.addToBackStack(null);
transaction.commit();

}
});
}

操作:執行 1.打開app,2.點擊Fragment,3.點擊Fragment2,4.點擊Fragment3。
此時清空LogCat,再點擊返回鍵Log如下:

 

 

 


此時界面回到Fragment2,而其他Fragment和Activity的生命周期是沒有變化的。若再點擊返回鍵將回到Fragment1界面,再點擊返回鍵就是回到Activity界面了。

(二) replace方法分析
修改 MainActivity 的方法initListener如下:(主要是替換add為replace)

private void initListener() {
mFragment1Tv.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Fragment1 fragment1= new Fragment1();
transaction = manager.beginTransaction();
transaction.replace(R.id.main_ll, fragment1,"1");
//transaction.add(R.id.main_ll, fragment1,"1");
// transaction.addToBackStack(null);
transaction.commit();
}
});
mFragment2Tv.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Fragment2 fragment2= new Fragment2();
transaction = manager.beginTransaction();
transaction.replace(R.id.main_ll, fragment2,"2");
//transaction.add(R.id.main_ll, fragment2,"2");
// transaction.addToBackStack(null);
transaction.commit();
}
});
mFragment3Tv.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Fragment3 fragment3= new Fragment3();
transaction = manager.beginTransaction();
transaction.replace(R.id.main_ll, fragment3,"3");
//transaction.add(R.id.main_ll, fragment3,"3");
//transaction.addToBackStack(null);
transaction.commit();

}
});
}

1.測試replace
操作:啟動app,然后點擊Fragment1,再點擊Fragment2,log如下:

 

 

 


2.測試返回鍵
在上一步驟的基礎上點擊物理返回鍵Log如下:(應用程序已經退出了)

 

 

 


3.在(二)1的基礎上點擊home鍵,再重新打開app,log如下:

 

 

 


4.此時看下會退棧的情況。
修改 MainActivity 的方法initListener,主要是取消

// transaction.addToBackStack(null);
1
的注釋。

操作:打開app,點擊Fragment1,點擊Fragment2,清空logCat,再點擊返回鍵,此時log如下:

 

 

 


可見replace 是會銷毀掉被replace 的Fragment。

(三) hide &show方法分析。
修改 MainActivity如下:(在activity的oncreate中add Fragment1和Fragment2,修改mFragment2Tv的點擊事件。)

public class MainActivity extends Activity{
final String TAG = "testFragment MainActivity";

TextView mFragment1Tv ;
TextView mFragment2Tv ;
TextView mFragment3Tv ;

FrameLayout mainll ;

FragmentManager manager ;
FragmentTransaction transaction;

Fragment1 fragment1;
Fragment2 fragment2;
Fragment3 fragment3;

 

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

initView();
initListener();
initData();

Log.d(TAG,"onCreate");
}

private void initListener() {
mFragment1Tv.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {

transaction = manager.beginTransaction();
transaction.add(R.id.main_ll, fragment1,"1");
transaction.commit();
}
});
mFragment2Tv.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
transaction = manager.beginTransaction();
transaction.hide(fragment1).show(fragment2);
transaction.commit();
}
});
mFragment3Tv.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {

transaction = manager.beginTransaction();
transaction.replace(R.id.main_ll, fragment3,"3");
// transaction.add(R.id.main_ll, fragment3,"3");
transaction.addToBackStack(null);
transaction.commit();

}
});
}

private void initData() {
manager = getFragmentManager();
fragment1= new Fragment1();
fragment2= new Fragment2();
fragment3= new Fragment3();
transaction = manager.beginTransaction();
transaction.add(R.id.main_ll, fragment2,"2");
transaction.add(R.id.main_ll, fragment1,"1");
transaction.commit();
}

private void initView() {
mFragment1Tv = (TextView) findViewById(R.id.fragment1_tv);
mFragment2Tv = (TextView) findViewById(R.id.fragment2_tv);
mFragment3Tv = (TextView) findViewById(R.id.fragment3_tv);
mainll = (FrameLayout) findViewById(R.id.main_ll);

}

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

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

@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");
}
}



操作:啟動app ,log如下圖,代碼里面是先add Fragment2 再add Fragment1,此時顯示的界面是Fragment1 的界面,然后點擊TextView mFragment2Tv,界面切換到了Fragment2上,而log無任何的信息打印,可見hide &show 方法不觸發Fragment生命周期,只影響它的顯示。

 

 

 


(四) remove方法分析
在 (三)hide&show方法分析 的代碼基礎上修改MainActivity 如下:
(其他代碼不變,只修改為remove方法)

mFragment2Tv.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
transaction = manager.beginTransaction();
transaction.remove(fragment1).show(fragment2);
transaction.commit();
}
});

啟動app 時的log:

 

 

 


此時點擊Fragment2,log如下

:

 

 

———————————————

版權聲明:本文為CSDN博主「hdcanta」的原創文章,遵循 CC 4.0 BY-SA 版權協議,轉載請附上原文出處鏈接及本聲明。
原文鏈接:https://blog.csdn.net/u014699958/article/details/52996143


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