fragment与回退栈back stack

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作用：因在同一ViewGroup中显示多个Fragment，因此需要回退到上一次的Fragment时，需要回退栈
FragmentTransaction.addToBackStack(String name) 将当前的Fragment增加到回退栈中

实例

逻辑代码--MainActivity

package com.example.week3_day2_fragment_backstack;import android.os.Bundle;import android.annotation.SuppressLint;import android.app.Activity;import android.app.FragmentManager;import android.app.FragmentTransaction;import android.view.Menu;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;public class MainActivity extends Activity implements OnClickListener {private Button btn1;private Button btn2;private Button btn3;private Button btn4;private FragmentManager manager;@SuppressLint("NewApi")@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);btn1 = (Button) findViewById(R.id.btn1);btn2 = (Button) findViewById(R.id.btn2);btn3 = (Button) findViewById(R.id.btn3);btn4 = (Button) findViewById(R.id.btn4);// 注册监听器btn1.setOnClickListener(this);btn2.setOnClickListener(this);btn3.setOnClickListener(this);btn4.setOnClickListener(this);manager = getFragmentManager();FragmentTransaction transaction = manager.beginTransaction();transaction.add(R.id.ld, new Fragment1());transaction.commit();}// 实现监听器中的方法@SuppressLint("NewApi")public void onClick(View v) {FragmentTransaction transaction = manager.beginTransaction();switch (v.getId()) {case R.id.btn1:transaction.replace(R.id.ld, new Fragment1());break;case R.id.btn2:transaction.replace(R.id.ld, new Fragment2());break;case R.id.btn3:transaction.replace(R.id.ld, new Fragment3());break;case R.id.btn4:transaction.replace(R.id.ld, new Fragment4());break;default:break;}//将Fragment保存到回退栈中  参数Tag  标记  如果没有的话  nulltransaction.addToBackStack(null);transaction.commit();}}

逻辑代码--fragment1

package com.example.week3_day2_fragment_backstack;import android.annotation.SuppressLint;import android.app.Fragment;import android.os.Bundle;import android.view.LayoutInflater;import android.view.View;import android.view.ViewGroup;@SuppressLint("NewApi") public class Fragment1 extends Fragment{@Overridepublic View onCreateView(LayoutInflater inflater, ViewGroup container,Bundle savedInstanceState) {View view = inflater.inflate(R.layout.fragment1, container,false);return view;}}

fragment2,fragment3,fragment4与fragment1一致,分别加载fragment2,fragment3,fragment4

布局文件--main.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:orientation="horizontal" >    <LinearLayout        android:id="@+id/ld1"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:orientation="horizontal" >        <Button        android:id="@+id/btn1"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="青春" />    <Button        android:id="@+id/btn2"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="校园" />    <Button        android:id="@+id/btn3"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="旅行" />    <Button        android:id="@+id/btn4"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="音乐" />    </LinearLayout>    <LinearLayout        android:id="@+id/ld"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:orientation="vertical" >    </LinearLayout></LinearLayout>

布局文件--fragment1

<?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:orientation="vertical" >    <TextView        android:id="@+id/tv1"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="青春" /></LinearLayout>

布局文件-fragment2,fragment3,fragment4与fragment1一致

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