教育系统APP(三)

秒速五厘米 2021-08-20 00:21 423阅读 0赞

挑战任务回顾教育系统APP(二)以及教育系统APP(三)

检验登录和注册模块。请修改MainActivity和LoginActivity，欢迎界面调转入主界面后，自动跳转入登录界面，登录成功后，返回主界面，在主界面的Hello World位置显示：用户名 “登录成功”。

解决方法

解决任务看看一下AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
    <manifest xmlns:android="http://schemas.android.com/apk/res/android"
        package="cn.edu.gdmec.android.boxuegu">
    
        
        
        
        <application
            android:allowBackup="true"
            android:icon="@drawable/app_icon"
            android:label="@string/app_name"
            android:roundIcon="@mipmap/ic_launcher_round"
            android:supportsRtl="true"
            android:theme="@style/Theme.AppCompat.NoActionBar">
            <activity android:name=".activity.SplashActivity">
                <intent-filter>
                    <action android:name="android.intent.action.MAIN" />
                    <category android:name="android.intent.category.LAUNCHER" />
                </intent-filter>
            </activity>
            
            <activity android:name=".activity.MainActivity"></activity>
            <activity android:name=".activity.LoginActivity"></activity>
            <activity android:name=".activity.RegisterActivity"></activity>
        </application>
    </manifest>

然后在MainActivity中编写代码，activity\_main.xml添加一下显示,把helloWord改为显示账号：

<?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"
        android:gravity="center">
    
        <TextView
            android:id="@ id/et_user_name"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="hello"
            android:layout_gravity="center"/>
    
    </LinearLayout>

package cn.edu.gdmec.android.boxuegu.activity;
    
    import android.content.Intent;
    import android.support.v7.app.AppCompatActivity;
    import android.os.Bundle;
    import android.widget.TextView;
    import android.widget.Toast;
    
    import cn.edu.gdmec.android.boxuegu.R;
    /*任务在主界面的Hello World位置显示：用户名 “登录成功”*/
    public class MainActivity extends AppCompatActivity {
        private TextView et_user_name;
    
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
            et_user_name = findViewById(R.id.et_user_name);
            Intent intent=new Intent(MainActivity.this,LoginActivity.class);
            startActivityForResult(intent,1);
        }
        @Override
        protected void onActivityResult(int requestCode, int resultCode, Intent data) {
            super.onActivityResult(requestCode, resultCode, data);
            if (data!=null){
                String userName = data.getStringExtra("userName");
                //if (!TextUtils.isEmpty(userName)){
                Toast.makeText(MainActivity.this,"登陆成功：" userName, Toast.LENGTH_SHORT).show();
                et_user_name.setText(userName);
                //}
            }
        }
    }

最后在LoginActivity下：

data.putExtra("userName",userName);

教育系统APP(三) 主界面学习目标:掌握注册和登录模块的开发，能够实现模块切换功能。

主页面,挑战任务

学习目标主界面有三个模块，分别为课程模块、习题模块、用户模块。用户点击底部导航栏可以实现三个模块的跳转。主界面用于做三个模块的切换。使用Fragment做为三个模块界面的载体。

任务实施放置图片资源本次实验要用到的图片资源有6个，分别为main*exercises*icon.png、main*course*icon.png、main*my*icon.pngmain*exercises*icon\_selected.png、main*course*icon\_selected.png、main*my*icon\_selected.png把要用到的图片资源放进drawrable文件夹中。

![file][]

activity\_main布局MainActivity页面主要包括两个区域：放Fragment的main\_body底部导航栏main*bottom*baractivity\_main.xml的完整代码

<?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="wrap_content"
        android:orientation="vertical">
        <LinearLayout
            android:orientation="vertical"
            android:background="@android:color/white"
            android:layout_width="match_parent"
            android:layout_height="match_parent">
            
            <include layout="@layout/main_title_bar"/>
            
            <RelativeLayout
                android:id="@ id/main_body"
                android:background="@android:color/white"
                android:layout_width="match_parent"
                android:layout_height="match_parent">
            </RelativeLayout>
        </LinearLayout>
    
        <LinearLayout
            android:id="@ id/main_bottom_bar"
            android:layout_alignParentBottom="true"
            android:background="#F2F2F2"
            android:orientation="horizontal"
            android:layout_width="match_parent"
            android:layout_height="55dp">
            <RelativeLayout
                android:layout_weight="1"
                android:id="@ id/bottom_bar_course_btn"
                android:layout_width="0dp"
                android:layout_height="match_parent">
                <TextView
                    android:id="@ id/bottom_bar_text_course"
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:layout_alignParentBottom="true"
                    android:layout_centerHorizontal="true"
                    android:layout_marginBottom="3dp"
                    android:gravity="center"
                    android:singleLine="true"
                    android:text="课 程"
                    android:textColor="#666666"
                    android:textSize="14sp"/>
                <ImageView
                    android:layout_width="27dp"
                    android:layout_height="27dp"
                    android:layout_above="@ id/bottom_bar_text_course"
                    android:layout_alignParentTop="true"
                    android:layout_centerHorizontal="true"
                    android:layout_marginTop="3dp"
                    android:id="@ id/bottom_bar_image_course"
                    android:src="@drawable/main_course_icon"/>
            </RelativeLayout>
            <RelativeLayout
                android:id="@ id/bottom_bar_exercises_btn"
                android:layout_weight="1"
                android:layout_width="0dp"
                android:layout_height="match_parent">
                <TextView
                    android:id="@ id/bottom_bar_text_exercises"
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:layout_alignParentBottom="true"
                    android:layout_centerHorizontal="true"
                    android:layout_marginBottom="3dp"
                    android:gravity="center"
                    android:singleLine="true"
                    android:text="习 题"
                    android:textColor="#666666"
                    android:textSize="14sp"/>
                <ImageView
                    android:layout_width="27dp"
                    android:layout_height="27dp"
                    android:layout_above="@ id/bottom_bar_text_exercises"
                    android:layout_alignParentTop="true"
                    android:layout_centerHorizontal="true"
                    android:layout_marginTop="3dp"
                    android:id="@ id/bottom_bar_image_exercises"
                    android:src="@drawable/main_exercises_icon"/>
            </RelativeLayout>
            <RelativeLayout
                android:layout_weight="1"
                android:id="@ id/bottom_bar_myinfo_btn"
                android:layout_width="0dp"
                android:layout_height="match_parent">
                <TextView
                    android:id="@ id/bottom_bar_text_myinfo"
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:layout_alignParentBottom="true"
                    android:layout_centerHorizontal="true"
                    android:layout_marginBottom="3dp"
                    android:gravity="center"
                    android:singleLine="true"
                    android:text="我"
                    android:textColor="#666666"
                    android:textSize="14sp"/>
                <ImageView
                    android:layout_width="27dp"
                    android:layout_height="27dp"
                    android:layout_above="@ id/bottom_bar_text_myinfo"
                    android:layout_alignParentTop="true"
                    android:layout_centerHorizontal="true"
                    android:layout_marginTop="3dp"
                    android:id="@ id/bottom_bar_image_myinfo"
                    android:src="@drawable/main_my_icon"/>
            </RelativeLayout>
        </LinearLayout>
    </RelativeLayout>

实例化控件点一下MainActivity

public class MainActivity extends AppCompatActivity {
        private RelativeLayout main_body;
        private TextView bottom_bar_text_course;
        private ImageView bottom_bar_image_course;
        private RelativeLayout bottom_bar_course_btn;
        private TextView bottom_bar_text_exercises;
        private ImageView bottom_bar_image_exercises;
        private RelativeLayout bottom_bar_exercises_btn;
        private TextView bottom_bar_text_myinfo;
        private ImageView bottom_bar_image_myinfo;
        private RelativeLayout bottom_bar_myinfo_btn;
        private LinearLayout main_bottom_bar;
    
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
            initView();
            setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);
        }
    
    
        private void initView() {
            main_body = findViewById(R.id.main_body);
            bottom_bar_text_course = findViewById(R.id.bottom_bar_text_course);
            bottom_bar_image_course = findViewById(R.id.bottom_bar_image_course);
            bottom_bar_course_btn = findViewById(R.id.bottom_bar_course_btn);
            bottom_bar_text_exercises = findViewById(R.id.bottom_bar_text_exercises);
            bottom_bar_image_exercises = findViewById(R.id.bottom_bar_image_exercises);
            bottom_bar_exercises_btn = findViewById(R.id.bottom_bar_exercises_btn);
            bottom_bar_text_myinfo = findViewById(R.id.bottom_bar_text_myinfo);
            bottom_bar_image_myinfo = findViewById(R.id.bottom_bar_image_myinfo);
            bottom_bar_myinfo_btn = findViewById(R.id.bottom_bar_myinfo_btn);
            main_bottom_bar = findViewById(R.id.main_bottom_bar);
        }
    
    }

控件实例化的部分就完成啦。

底部导航栏状态的切换方法底部导航栏在点击切换时，会有变色的效果。

![file][file 1]

给MainActivity加一个setSelectStatus（）方法。

private void setSelectStatus(int index) {
            switch (index){
                case 0:
                    bottom_bar_image_course.setImageResource(R.drawable.main_course_icon_selected);
                    bottom_bar_text_course.setTextColor(Color.parseColor("#0097F7"));
                    bottom_bar_text_exercises.setTextColor(Color.parseColor("#666666"));
                    bottom_bar_text_myinfo.setTextColor(Color.parseColor("#666666"));
                    bottom_bar_image_exercises.setImageResource(R.drawable.main_exercises_icon);
                    bottom_bar_image_myinfo.setImageResource(R.drawable.main_my_icon);
                    break;
                case 1:
                    bottom_bar_image_exercises.setImageResource(R.drawable.main_exercises_icon_selected);
                    bottom_bar_text_exercises.setTextColor(Color.parseColor("#0097F7"));
                    bottom_bar_text_course.setTextColor(Color.parseColor("#666666"));
                    bottom_bar_text_myinfo.setTextColor(Color.parseColor("#666666"));
                    bottom_bar_image_course.setImageResource(R.drawable.main_course_icon);
                    bottom_bar_image_myinfo.setImageResource(R.drawable.main_my_icon);
                    break;
                case 2:
                    bottom_bar_image_myinfo.setImageResource(R.drawable.main_my_icon_selected);
                    bottom_bar_text_myinfo.setTextColor(Color.parseColor("#0097F7"));
                    bottom_bar_text_course.setTextColor(Color.parseColor("#666666"));
                    bottom_bar_text_exercises.setTextColor(Color.parseColor("#666666"));
                    bottom_bar_image_exercises.setImageResource(R.drawable.main_exercises_icon);
                    bottom_bar_image_course.setImageResource(R.drawable.main_course_icon);
                    break;
            }
        }

在setSelectStatus（）方法里用参数index来判断当前选的按钮。

底部导航栏的响应导航栏颜色切换效果的方法写好了，接下来是点击响应的方法。先给MainActivity加上View.OnClickListener接口

public class MainActivity extends AppCompatActivity implements View.OnClickListener{

Alt 回车生成onClick() 方法在生成的onClick（）方法中加上导航栏区域的响应。

@Override
        public void onClick(View v) {
            switch (v.getId()){
                case R.id.bottom_bar_course_btn:
                    setSelectStatus(0);
                    break;
                case R.id.bottom_bar_exercises_btn:
                    setSelectStatus(1);
                    break;
                case R.id.bottom_bar_myinfo_btn:
                    setSelectStatus(2);
                    break;
            }
        }

别忘了给三个RelativeLayout控件加上监听器，我的习惯是在initView（）方法里加。

bottom_bar_course_btn.setOnClickListener(this);
            bottom_bar_exercises_btn.setOnClickListener(this);
            bottom_bar_myinfo_btn.setOnClickListener(this);

至此，底部导航栏的代码就完成了。

private void initView() {
            main_body = findViewById(R.id.main_body);
            bottom_bar_text_course = findViewById(R.id.bottom_bar_text_course);
            bottom_bar_image_course = findViewById(R.id.bottom_bar_image_course);
            bottom_bar_course_btn = findViewById(R.id.bottom_bar_course_btn);
            bottom_bar_text_exercises = findViewById(R.id.bottom_bar_text_exercises);
            bottom_bar_image_exercises = findViewById(R.id.bottom_bar_image_exercises);
            bottom_bar_exercises_btn = findViewById(R.id.bottom_bar_exercises_btn);
            bottom_bar_text_myinfo = findViewById(R.id.bottom_bar_text_myinfo);
            bottom_bar_image_myinfo = findViewById(R.id.bottom_bar_image_myinfo);
            bottom_bar_myinfo_btn = findViewById(R.id.bottom_bar_myinfo_btn);
            main_bottom_bar = findViewById(R.id.main_bottom_bar);
    
            bottom_bar_course_btn.setOnClickListener(this);
            bottom_bar_exercises_btn.setOnClickListener(this);
            bottom_bar_myinfo_btn.setOnClickListener(this);
        }

三个fragment的创建我们还是用Fragment的方法来做三个模块的界面吧。首先新建3个布局文件。fragment\_course.xmlfragment\_exercises.xmlfragment\_myinfo.xml布局文件的内容都相似，一个大大的TextView，里面写着Fragment\_1/2/3。记得改背景颜色和字体颜色。

fragment\_course.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="@android:color/white">
        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Fragment_1"
            android:textColor="@android:color/black"
            android:textSize="50sp"/>
    </LinearLayout>
    fragment_exercises.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="@android:color/white">
        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Fragment_2"
            android:textColor="@android:color/black"
            android:textSize="50sp"/>
    </LinearLayout>

fragment\_myinfo.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="@android:color/white">
        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Fragment_3"
            android:textColor="@android:color/black"
            android:textSize="50sp"/>
    </LinearLayout>

建一个Fragment包，把三个Fragment放进去CourseFragment.java

package cn.edu.gdmec.android.boxuegu.fragment;
    
    import android.os.Bundle;
    import android.support.v4.app.Fragment;
    import android.view.LayoutInflater;
    import android.view.View;
    import android.view.ViewGroup;
    
    import cn.edu.gdmec.android.boxuegu.R;
    
    public class CourseFragment extends Fragment {
    
    
        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container,
                                 Bundle savedInstanceState) {
            return inflater.inflate(R.layout.fragment_course, null);
        }
    
        @Override
        public void onViewCreated(View view, Bundle savedInstanceState) {
            super.onViewCreated(view, savedInstanceState);
    
        }
    }

ExercisesFragment.java

package cn.edu.gdmec.android.boxuegu.fragment;
    
    import android.os.Bundle;
    import android.support.v4.app.Fragment;
    import android.view.LayoutInflater;
    import android.view.View;
    import android.view.ViewGroup;
    
    import cn.edu.gdmec.android.boxuegu.R;
    
    public class ExercisesFragment extends Fragment {
    
        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container,
                                 Bundle savedInstanceState) {
            return inflater.inflate(R.layout.fragment_exercises, null);
        }
    
        @Override
        public void onViewCreated(View view, Bundle savedInstanceState) {
            super.onViewCreated(view, savedInstanceState);
    
        }
    
    }

MyinfoFragment.java

package cn.edu.gdmec.android.boxuegu.fragment;
    
    import android.os.Bundle;
    import android.support.v4.app.Fragment;
    import android.view.LayoutInflater;
    import android.view.View;
    import android.view.ViewGroup;
    
    import cn.edu.gdmec.android.boxuegu.R;
    
    public class MyinfoFragment extends Fragment {
    
        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container,
                                 Bundle savedInstanceState) {
            return inflater.inflate(R.layout.fragment_myinfo, null);
        }
    
        @Override
        public void onViewCreated(View view, Bundle savedInstanceState) {
            super.onViewCreated(view, savedInstanceState);
    
        }
    
    }

三个fragment的显示和切换Fragment用的是android.support.v4.app.Fragment接下来我们在MainActivity里把AppCompatActivity改为FragmentActivity。

public class MainActivity extends FragmentActivity implements View.OnClickListener{

把Fragment加到Activity里的代码如下

FragmentManager manager = getSupportFragmentManager();
    FragmentTransaction transaction = manager.beginTransaction();
    transaction.add(R.id.main_body,new CourseFragment()).commit();

我们写一个setMain（）方法，用于打开初始页面

private void setMain() {
            this.getSupportFragmentManager().beginTransaction().add(R.id.main_body,new CourseFragment()).commit();
            setSelectStatus(0);
        }

这里面用的是连写，跟上面Fragment加到Activity的代码是一样效果的，这个看个人习惯。

在onCreate()方法里调用

@Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
            initView();
            setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);
            setMain();
        }

点击底部导航栏时，要切换响应的fragment，我们在onClick()方法里加上Fragment切换的方法。

@Override
        public void onClick(View v) {
            switch (v.getId()){
                case R.id.bottom_bar_course_btn:
                    getSupportFragmentManager().beginTransaction().add(R.id.main_body,new CourseFragment()).commit();
                    setSelectStatus(0);
                    break;
                case R.id.bottom_bar_exercises_btn:
                    getSupportFragmentManager().beginTransaction().add(R.id.main_body,new ExercisesFragment()).commit();
                    setSelectStatus(1);
                    break;
                case R.id.bottom_bar_myinfo_btn:
                    getSupportFragmentManager().beginTransaction().add(R.id.main_body,new MyinfoFragment()).commit();
                    setSelectStatus(2);
                    break;
            }
        }

完整的MainActivity.java

package cn.edu.gdmec.android.boxuegu.activity;
    
    import android.content.pm.ActivityInfo;
    import android.graphics.Color;
    import android.os.Bundle;
    import android.support.v4.app.FragmentActivity;
    import android.view.View;
    import android.widget.ImageView;
    import android.widget.LinearLayout;
    import android.widget.RelativeLayout;
    import android.widget.TextView;
    
    import cn.edu.gdmec.android.boxuegu.R;
    import cn.edu.gdmec.android.boxuegu.fragment.CourseFragment;
    import cn.edu.gdmec.android.boxuegu.fragment.ExercisesFragment;
    import cn.edu.gdmec.android.boxuegu.fragment.MyinfoFragment;
    
    /*任务在主界面的Hello World位置显示：用户名 “登录成功”*/
    public class MainActivity extends FragmentActivity implements View.OnClickListener{
        private RelativeLayout main_body;
        private TextView bottom_bar_text_course;
        private ImageView bottom_bar_image_course;
        private RelativeLayout bottom_bar_course_btn;
        private TextView bottom_bar_text_exercises;
        private ImageView bottom_bar_image_exercises;
        private RelativeLayout bottom_bar_exercises_btn;
        private TextView bottom_bar_text_myinfo;
        private ImageView bottom_bar_image_myinfo;
        private RelativeLayout bottom_bar_myinfo_btn;
        private LinearLayout main_bottom_bar;
    
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
            initView();
            setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);
            //把Fragment加到Activity里的代码如下
           /* FragmentManager manager = getSupportFragmentManager();
            FragmentTransaction transaction = manager.beginTransaction();
            transaction.add(R.id.main_body,new CourseFragment()).commit();*/
           setMain();
        }
    
        private void setMain() {
            this.getSupportFragmentManager().beginTransaction().add(R.id.main_body,new MyinfoFragment()).commit();
            setSelectStatus(2);
        }
    
        private void setSelectStatus(int index) {
            switch (index){
                case 0:
                    bottom_bar_image_course.setImageResource(R.drawable.main_course_icon_selected);
                    bottom_bar_text_course.setTextColor(Color.parseColor("#0097F7"));
                    bottom_bar_text_exercises.setTextColor(Color.parseColor("#666666"));
                    bottom_bar_text_myinfo.setTextColor(Color.parseColor("#666666"));
                    bottom_bar_image_exercises.setImageResource(R.drawable.main_exercises_icon);
                    bottom_bar_image_myinfo.setImageResource(R.drawable.main_my_icon);
                    break;
                case 1:
                    bottom_bar_image_exercises.setImageResource(R.drawable.main_exercises_icon_selected);
                    bottom_bar_text_exercises.setTextColor(Color.parseColor("#0097F7"));
                    bottom_bar_text_course.setTextColor(Color.parseColor("#666666"));
                    bottom_bar_text_myinfo.setTextColor(Color.parseColor("#666666"));
                    bottom_bar_image_course.setImageResource(R.drawable.main_course_icon);
                    bottom_bar_image_myinfo.setImageResource(R.drawable.main_my_icon);
                    break;
                case 2:
                    bottom_bar_image_myinfo.setImageResource(R.drawable.main_my_icon_selected);
                    bottom_bar_text_myinfo.setTextColor(Color.parseColor("#0097F7"));
                    bottom_bar_text_course.setTextColor(Color.parseColor("#666666"));
                    bottom_bar_text_exercises.setTextColor(Color.parseColor("#666666"));
                    bottom_bar_image_exercises.setImageResource(R.drawable.main_exercises_icon);
                    bottom_bar_image_course.setImageResource(R.drawable.main_course_icon);
                    break;
            }
        }
        private void initView() {
            main_body = findViewById(R.id.main_body);
            bottom_bar_text_course = findViewById(R.id.bottom_bar_text_course);
            bottom_bar_image_course = findViewById(R.id.bottom_bar_image_course);
            bottom_bar_course_btn = findViewById(R.id.bottom_bar_course_btn);
            bottom_bar_text_exercises = findViewById(R.id.bottom_bar_text_exercises);
            bottom_bar_image_exercises = findViewById(R.id.bottom_bar_image_exercises);
            bottom_bar_exercises_btn = findViewById(R.id.bottom_bar_exercises_btn);
            bottom_bar_text_myinfo = findViewById(R.id.bottom_bar_text_myinfo);
            bottom_bar_image_myinfo = findViewById(R.id.bottom_bar_image_myinfo);
            bottom_bar_myinfo_btn = findViewById(R.id.bottom_bar_myinfo_btn);
            main_bottom_bar = findViewById(R.id.main_bottom_bar);
    
            bottom_bar_course_btn.setOnClickListener(this);
            bottom_bar_exercises_btn.setOnClickListener(this);
            bottom_bar_myinfo_btn.setOnClickListener(this);
        }
    
        @Override
        public void onClick(View v) {
            switch (v.getId()){
                case R.id.bottom_bar_course_btn:
                    getSupportFragmentManager().beginTransaction().add(R.id.main_body,new CourseFragment()).commit();
                    setSelectStatus(0);
                    break;
                case R.id.bottom_bar_exercises_btn:
                    getSupportFragmentManager().beginTransaction().add(R.id.main_body,new ExercisesFragment()).commit();
                    setSelectStatus(1);
                    break;
                case R.id.bottom_bar_myinfo_btn:
                    getSupportFragmentManager().beginTransaction().add(R.id.main_body,new MyinfoFragment()).commit();
                    setSelectStatus(2);
                    break;
            }
        }
    }

好了，完成，这里没有新添加的activity的类。接下来进行挑战任务！

挑战任务初次打开页面都是Fragment*1，请修改相关代码，让初始打开的页面为Fragment*3，别忘了底部导航栏也要变颜色哦

总结这是走好Android的三步！

## ❤️ 不要忘记留下你学习的脚印 \[点赞 收藏 评论\] ##

作者Info：

> 【作者】：Jeskson
> 
> 【原创公众号】：达达前端小酒馆。
> 
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> 
> 【转载说明】：转载请说明出处，谢谢合作！~

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