碎片(Fragment) 嵌入与活动中的UI片段，为了合理的分配布局而存在，这是我的简单理解。多用于兼顾手机与平板的UI，也适用于灵活高级的UI制作。

Demo 简单的按键切换两片不同的Demo

新建left_fragment.xml

android:id="@+id/button"android:layout_width="match_parent"android:layout_height="wrap_content"android:layout_gravity="center_horizontal"android:text="Button"

/>

新建right_fragment.xml

android:layout_width="wrap_content"android:layout_height="wrap_content"android:layout_gravity="center_horizontal"android:textSize="20sp"android:text="This is right fragment"/>

新建another_right_fragment.xml

android:layout_width="wrap_content"android:layout_height="wrap_content"android:layout_gravity="center_horizontal"android:textSize="20sp"android:text="This is right fragment"/>

main_Activity.xml

>

android:layout_width="0dp"android:name="test.example.com.fragmenttest.LeftFragment"android:layout_height="match_parent"android:layout_weight="1"android:id="@+id/left_fragment"/>

android:id="@+id/right_layout"android:layout_width="0dp"android:layout_height="match_parent"android:layout_weight="1">

分别新建对应的类

packagetest.example.com.fragmenttest;importandroid.app.Fragment;importandroid.os.Bundle;importandroid.view.LayoutInflater;importandroid.view.View;importandroid.view.ViewGroup;/*** Created by hs769 on 2017/4/4.*/

public class LeftFragment extendsFragment {

@OverridepublicView onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState){

View view=inflater.inflate(R.layout.lift_fregment,container,false);returnview;

}

}

packagetest.example.com.fragmenttest;//import android.app.Fragment;

importandroid.support.v4.app.Fragment;importandroid.os.Bundle;importandroid.view.LayoutInflater;importandroid.view.View;importandroid.view.ViewGroup;/*** Created by hs769 on 2017/4/4.*/

public class RightFragment extendsFragment{

@OverridepublicView onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState){

View view=inflater.inflate(R.layout.right_fragment,container,false);returnview;

}

}

packagetest.example.com.fragmenttest;importandroid.support.v4.app.Fragment;importandroid.os.Bundle;importandroid.view.LayoutInflater;importandroid.view.View;importandroid.view.ViewGroup;/*** Created by hs769 on 2017/4/4.*/

public class AnotherRightFragment extendsFragment {

@OverridepublicView onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState){

View view=inflater.inflate(R.layout.another_right_fragment,container,false);returnview;

}

}

packagetest.example.com.fragmenttest;importandroid.support.v4.app.Fragment;importandroid.support.v4.app.FragmentManager;importandroid.support.v4.app.FragmentTransaction;importandroid.support.v7.app.AppCompatActivity;importandroid.os.Bundle;importandroid.view.View;importandroid.widget.Button;public class MainActivity extends AppCompatActivity implementsView.OnClickListener{

@Overrideprotected voidonCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

Button button=(Button)findViewById(R.id.button);

button.setOnClickListener(this);

replaceFragment(newRightFragment());

}

@Overridepublic voidonClick(View v) {switch(v.getId()){caseR.id.button:

replaceFragment(newAnotherRightFragment());break;default:break;

}

}private voidreplaceFragment(Fragment fragment){

FragmentManager fragmentManager=getSupportFragmentManager();

FragmentTransaction transaction=fragmentManager.beginTransaction();

transaction.replace(R.id.right_layout,fragment);

transaction.commit();

}

}

LeftFragment，RightFragment和another_Right_Fragment这三个类分别extends(继承)Fragment类，这是一个关键，因为有两个包中含有Fragment，建议选择android.support.v4.app.Fragment

如果包选择不一样会出现如下错误(MainAcitvity.java)，如图更改即可：找到出问题的类，更换包，完毕

最终效果实现点击button切换碎片(下图为点击前后的变化，分别为两个Fragment)