一个Activity分别加载多个layout布局文件

   本程序只有一个Activity，首先加载activity_main布局文件。通过点击不同的按钮，分别加载不同的布局文件layout_1、layout_2、layout_3。

   activity_main.xml文件如下：

<?xml version="1.0" encoding="utf-8"?><android.support.constraint.ConstraintLayout    xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:app="http://schemas.android.com/apk/res-auto"    xmlns:tools="http://schemas.android.com/tools"    android:layout_width="match_parent"    android:layout_height="match_parent"    tools:context="com.horrorkwangmail.a20171208_multilayout.ActivityMain">    <TextView        android:id="@+id/textView"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_marginTop="20dp"        android:text="This is Layout main"        android:textAllCaps="false"        android:textSize="25sp"        app:layout_constraintLeft_toLeftOf="parent"        app:layout_constraintRight_toRightOf="parent"        app:layout_constraintTop_toTopOf="parent"/>    <Button        android:id="@+id/buttonLayout1"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_marginTop="40dp"        android:text="Layout 1"        android:textAllCaps="false"        app:layout_constraintEnd_toStartOf="@+id/buttonLayout2"        app:layout_constraintStart_toStartOf="parent"        app:layout_constraintTop_toBottomOf="@+id/textView"        android:onClick="buttonClick"/>    <Button        android:id="@+id/buttonLayout2"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_marginBottom="8dp"        android:layout_marginTop="8dp"        android:text="Layout 2"        android:textAllCaps="false"        app:layout_constraintBottom_toBottomOf="@+id/buttonLayout1"        app:layout_constraintEnd_toStartOf="@+id/buttonLayout3"        app:layout_constraintStart_toEndOf="@+id/buttonLayout1"        app:layout_constraintTop_toTopOf="@+id/buttonLayout1"        android:onClick="buttonClick"/>    <Button        android:id="@+id/buttonLayout3"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="Layout 3"        android:textAllCaps="false"        app:layout_constraintBottom_toBottomOf="@+id/buttonLayout2"        app:layout_constraintEnd_toEndOf="parent"        app:layout_constraintStart_toEndOf="@+id/buttonLayout2"        app:layout_constraintTop_toTopOf="@+id/buttonLayout2"        android:onClick="buttonClick"/></android.support.constraint.ConstraintLayout>

     layout_1.xml文件如下：

<?xml version="1.0" encoding="utf-8"?><android.support.constraint.ConstraintLayout    xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:app="http://schemas.android.com/apk/res-auto"    xmlns:tools="http://schemas.android.com/tools"    android:layout_width="match_parent"    android:layout_height="match_parent">    <Button        android:id="@+id/buttonBack"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_marginBottom="8dp"        android:layout_marginEnd="8dp"        android:layout_marginStart="8dp"        android:layout_marginTop="8dp"        android:text="Back to Layout main"        android:textAllCaps="false"        app:layout_constraintBottom_toBottomOf="parent"        app:layout_constraintEnd_toEndOf="parent"        app:layout_constraintStart_toStartOf="parent"        app:layout_constraintTop_toTopOf="parent"/>    <TextView        android:id="@+id/textView"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_marginBottom="8dp"        android:layout_marginEnd="8dp"        android:layout_marginStart="8dp"        android:layout_marginTop="30dp"        android:text="This is Layout 1"        android:textSize="25sp"        android:textAllCaps="false"        app:layout_constraintBottom_toTopOf="@+id/buttonBack"        app:layout_constraintEnd_toEndOf="parent"        app:layout_constraintStart_toStartOf="parent"        app:layout_constraintTop_toTopOf="parent"/></android.support.constraint.ConstraintLayout>

layout_2.xml文件如下：

<?xml version="1.0" encoding="utf-8"?><android.support.constraint.ConstraintLayout    xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:app="http://schemas.android.com/apk/res-auto"    xmlns:tools="http://schemas.android.com/tools"    android:layout_width="match_parent"    android:layout_height="match_parent">    <Button        android:id="@+id/buttonBack"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_marginBottom="8dp"        android:layout_marginEnd="8dp"        android:layout_marginStart="8dp"        android:layout_marginTop="8dp"        android:text="Back to Layout main"        android:textAllCaps="false"        app:layout_constraintBottom_toBottomOf="parent"        app:layout_constraintEnd_toEndOf="parent"        app:layout_constraintStart_toStartOf="parent"        app:layout_constraintTop_toTopOf="parent"/>    <TextView        android:id="@+id/textView"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_marginBottom="8dp"        android:layout_marginEnd="8dp"        android:layout_marginStart="8dp"        android:layout_marginTop="30dp"        android:text="This is Layout 2"        android:textSize="25sp"        android:textAllCaps="false"        app:layout_constraintBottom_toTopOf="@+id/buttonBack"        app:layout_constraintEnd_toEndOf="parent"        app:layout_constraintStart_toStartOf="parent"        app:layout_constraintTop_toTopOf="parent"/></android.support.constraint.ConstraintLayout>

layout_3.xml文件如下：

<?xml version="1.0" encoding="utf-8"?><android.support.constraint.ConstraintLayout    xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:app="http://schemas.android.com/apk/res-auto"    xmlns:tools="http://schemas.android.com/tools"    android:layout_width="match_parent"    android:layout_height="match_parent">    <Button        android:id="@+id/buttonBack"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_marginBottom="8dp"        android:layout_marginEnd="8dp"        android:layout_marginStart="8dp"        android:layout_marginTop="8dp"        android:text="Back to Layout main"        android:textAllCaps="false"        app:layout_constraintBottom_toBottomOf="parent"        app:layout_constraintEnd_toEndOf="parent"        app:layout_constraintStart_toStartOf="parent"        app:layout_constraintTop_toTopOf="parent"/>    <TextView        android:id="@+id/textView"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_marginBottom="8dp"        android:layout_marginEnd="8dp"        android:layout_marginStart="8dp"        android:layout_marginTop="30dp"        android:text="This is Layout 3"        android:textSize="25sp"        android:textAllCaps="false"        app:layout_constraintBottom_toTopOf="@+id/buttonBack"        app:layout_constraintEnd_toEndOf="parent"        app:layout_constraintStart_toStartOf="parent"        app:layout_constraintTop_toTopOf="parent"/></android.support.constraint.ConstraintLayout>

strings.xml文件如下：

<resources>    <string name="app_name">MultiLayout</string>    <string name="layoutMain">Layout main</string>    <string name="layout1">Layout 1</string>    <string name="layout2">Layout 2</string>    <string name="layout3">Layout 3</string></resources>

ActivityMain.java文件如下：

package com.horrorkwangmail.a20171208_multilayout;import android.support.v7.app.AppCompatActivity;import android.os.Bundle;import android.view.View;import android.widget.Button;public class ActivityMain extends AppCompatActivity{    @Override    protected void onCreate(Bundle savedInstanceState)    {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);  //首先加载activity_main布局文件        this.setTitle(R.string.layoutMain);  //设置标题栏名称    }    public void buttonClick(View v)    {        switch (v.getId())        {            case R.id.buttonLayout1:                setContentView(R.layout.layout_1);  //加载layout_1布局文件                this.setTitle(R.string.layout1);  //设置标题栏名称                //点击按钮，回到activity_main布局文件                //并设置标题栏名称                Button buttonBack1=findViewById(R.id.buttonBack);                buttonBack1.setOnClickListener(new View.OnClickListener()                {                    @Override                    public void onClick(View view)                    {                        setContentView(R.layout.activity_main);                        setTitle(R.string.layoutMain);                    }                });                break;            case R.id.buttonLayout2:                setContentView(R.layout.layout_2);  //加载layout_2布局文件                this.setTitle(R.string.layout2);  //设置标题栏名称                //点击按钮，回到activity_main布局文件                //并设置标题栏名称                Button buttonBack2=findViewById(R.id.buttonBack);                buttonBack2.setOnClickListener(new View.OnClickListener()                {                    @Override                    public void onClick(View view)                    {                        setContentView(R.layout.activity_main);                        setTitle(R.string.layoutMain);                    }                });                break;            case R.id.buttonLayout3:                setContentView(R.layout.layout_3);  //加载layout_3布局文件                this.setTitle(R.string.layout3);  //设置标题栏名称                //点击按钮，回到activity_main布局文件                //并设置标题栏名称                Button buttonBack3=findViewById(R.id.buttonBack);                buttonBack3.setOnClickListener(new View.OnClickListener()                {                    @Override                    public void onClick(View view)                    {                        setContentView(R.layout.activity_main);                        setTitle(R.string.layoutMain);                    }                });                break;            default:                break;        }    }        }

真机测试如下：