Fragment与Radiogroup联动，经典的主界面布局。使用show和hide的方式实现；

Fragment+RadioGroup经典的主界面布局，方便实用；

1、使用replace方式：

直接上代码，先是布局文件；<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">

<RelativeLayout
android:id="@+id/rl"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:background="#ffffff">

<RadioGroup
android:id="@+id/rg"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="#ffffff"
android:orientation="horizontal">

<RadioButton
android:id="@+id/rb_home"
style="@style/main_tab_button"
android:drawableTop="@drawable/rgbtn_home_select"
android:text="主页"/>

<RadioButton
android:id="@+id/rb_shoppingcart"
style="@style/main_tab_button"
android:drawableTop="@drawable/rgbtn_gouwuche_select"
android:text="购物车"/>

<RadioButton
android:id="@+id/rb_orderfrom"
style="@style/main_tab_button"
android:drawableTop="@drawable/rgbtn_orderfrom_select"
android:text="分类"/>

<RadioButton
android:id="@+id/rb_my"
style="@style/main_tab_button"
android:drawableTop="@drawable/rgbtn_my_select"
android:text="个人"/>
</RadioGroup>
<View
style="@style/Line_e0e0e0_Horizontal"/>
</RelativeLayout>
<FrameLayout
android:id="@+id/fl"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_above="@id/rl"
></FrameLayout>
</RelativeLayout>Radiogroup的style：
<style name="main_tab_button">
<item name="android:textSize">12dp</item>
<item name="android:textColor"&
109c8
gt;@drawable/rgbtn_select</item>
<item name="android:ellipsize">marquee</item>
<item name="android:gravity">center</item>
<item name="android:paddingBottom">2dp</item>
<item name="android:background">#ffffff</item>
<item name="android:layout_width">0dp</item>
<item name="android:layout_weight">1.0</item>
<item name="android:layout_height">wrap_content</item>
<item name="android:button">@null</item>
<item name="android:singleLine">true</item>
<item name="android:drawablePadding">2dp</item>
</style>文字的状态选择器：
<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
<item android:color="#666666" android:state_checked="false"/>
<item android:color="#424242" android:state_checked="true"/>
</selector>
图片状态选择器：

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
<item android:drawable="@drawable/datahui_def" android:state_checked="false"/>
<item android:drawable="@drawable/datahui_sel" android:state_checked="true"/>
</selector>好了，核心代码：
public class FragmentReplaceActivity extends AppCompatActivity {

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(getContentViewResource());
initView();
initData();
initList();
}
private RadioGroup rg;
private Fragment HomeFm = null,SpcFm = null, OrderFm = null, MyFm = null;

private final class RadioGroupOnCheckedChangeListener implements RadioGroup.OnCheckedChangeListener {
@Override
public void onCheckedChanged(RadioGroup radioGroup, int checkedId) {
/**
* 替换fragment
*/
switch (checkedId) {
case R.id.rb_home:
getSupportFragmentManager().beginTransaction().replace(R.id.fl, HomeFm).commit();
break;
case R.id.rb_shoppingcart:
getSupportFragmentManager().beginTransaction().replace(R.id.fl, SpcFm).commit();
break;
case R.id.rb_orderfrom:
getSupportFragmentManager().beginTransaction().replace(R.id.fl, OrderFm).commit();
break;
case R.id.rb_my:
getSupportFragmentManager().beginTransaction().replace(R.id.fl, MyFm).commit();
break;
}
}
}

public int getContentViewResource() {
return R.layout.activity_fragment;
}

protected void initView() {
rg = findViewById(R.id.rg);
}

protected void initData() {
HomeFm = new Fragment1();
SpcFm = new Fragment2();
OrderFm = new Fragment3();
MyFm = new Fragment4();
}

protected void initList() {
rg.setOnCheckedChangeListener(new RadioGroupOnCheckedChangeListener());
rg.check(R.id.rb_home);
}
}这样，一个简单的使用replace点击切换界面就好了；不过这样的方式不太好，每次切换都要走一遍fragment中所有的方法，好来介绍下一种：

2、Add，Show，Hide；隐藏和显示fragment；

public class FragmentShowHideActivity extends AppCompatActivity {

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(getContentViewResource());
initView();
initData();
initList();
}

private FrameLayout fl;
private RadioGroup rg;
private Fragment HomeFm = null,SpcFm = null, OrderFm = null, MyFm = null;

private final class RadioGroupOnCheckedChangeListener implements RadioGroup.OnCheckedChangeListener {
@Override
public void onCheckedChanged(RadioGroup radioGroup, int checkedId) {
if (HomeFm != null) {
getSupportFragmentManager().beginTransaction().hide(HomeFm).commit();
}
if (SpcFm != null) {
getSupportFragmentManager().beginTransaction().hide(SpcFm).commit();
}
if (OrderFm != null) {
getSupportFragmentManager().beginTransaction().hide(OrderFm).commit();
}
if (MyFm != null) {
getSupportFragmentManager().beginTransaction().hide(MyFm).commit();
}
switch (checkedId) {
case R.id.rb_home:
if (HomeFm == null) {
HomeFm = new Fragment1();
getSupportFragmentManager().beginTransaction().add(R.id.fl, HomeFm).commit();
} else {
getSupportFragmentManager().beginTransaction().show(HomeFm).commit();
}
break;
case R.id.rb_shoppingcart:
if (SpcFm == null) {
SpcFm = new Fragment2();
getSupportFragmentManager().beginTransaction().add(R.id.fl, SpcFm).commit();
} else {
getSupportFragmentManager().beginTransaction().show(SpcFm).commit();
}
break;

case R.id.rb_orderfrom:
if (OrderFm == null) {
OrderFm = new Fragment3();
getSupportFragmentManager().beginTransaction().add(R.id.fl, OrderFm).commit();
} else {
getSupportFragmentManager().beginTransaction().show(OrderFm).commit();
}
break;
case R.id.rb_my:
if (MyFm == null) {
MyFm = new Fragment4();
getSupportFragmentManager().beginTransaction().add(R.id.fl, MyFm).commit();
} else {
getSupportFragmentManager().beginTransaction().show(MyFm).commit();
}
break;
}
}
}

public int getContentViewResource() {
return R.layout.activity_fragment;
}

protected void initView() {
fl = findViewById(R.id.fl);
rg = findViewById(R.id.rg);

}

protected void initData() {
}

protected void initList() {
rg.setOnCheckedChangeListener(new RadioGroupOnCheckedChangeListener());
rg.check(R.id.rb_home);
}
}
简化一下是这样的：使用isAdded方法判断是否添加过；
public class FragmentShowHide2Activity extends AppCompatActivity {

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(getContentViewResource());
initView();
initData();
initList();
}

private RadioGroup rg;
private Fragment HomeFm = null,SpcFm = null, OrderFm = null, MyFm = null;

private final class RgOnCheckedChangeListener implements RadioGroup.OnCheckedChangeListener {
@Override
public void onCheckedChanged(RadioGroup radioGroup, int checkedId) {
switch (checkedId) {
case R.id.rb_home:
switchFragment(showFragment,HomeFm);
break;
case R.id.rb_shoppingcart:
switchFragment(showFragment,SpcFm);
break;
case R.id.rb_orderfrom:
switchFragment(showFragment,OrderFm);
break;
case R.id.rb_my:
switchFragment(showFragment,MyFm);
break;
}
}
}

public int getContentViewResource() {
return R.layout.activity_fragment;
}

protected void initView() {
rg = findViewById(R.id.rg);

}

protected void initData() {
HomeFm = new Fragment1();
SpcFm = new Fragment2();
OrderFm = new Fragment3();
MyFm = new Fragment4();
}

protected void initList() {
rg.setOnCheckedChangeListener(new RgOnCheckedChangeListener());
rg.check(R.id.rb_home);
}

private Fragment showFragment; //当前显示的fragment

private void switchFragment(Fragment hide,Fragment show){
FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
if (hide == show)return;
if (hide != null){
if (!show.isAdded()){
ft.hide(hide).add(R.id.fl, show).commit();
}else{
ft.hide(hide).show(show).commit();
}
}else {
if (!show.isAdded()){
ft.add(R.id.fl, show).commit();
}else{
ft.show(show).commit();
}
}
showFragment = show;
}
}下载Demo:FragmentDemo
github：Github
附：使用show和hide的方式显示Fragment,在Activity回收后重叠的问题；
随意门：https://blog.csdn.net/qq_35605213/article/details/79713871