frag

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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.example.yuekaomoni_99.MainActivity">

    <RadioGroup
        android:layout_width="match_parent"
        android:background="#f00"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        android:layout_alignParentBottom="true"
        android:id="@+id/rg">
        <RadioButton
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:id="@+id/rb_index"
            android:checked="true"
            android:layout_weight="1"
            android:text="首页"

            android:button="@null"
            android:gravity="center"/>

        <!--文字颜色的改变   1.res新建一个color文件夹  2.color文件夹内 新建selector，<item android:color=""  3.radiobutton的属性 android:textColor=@color/....>-->
        <RadioButton
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:id="@+id/rb_mind"
            android:layout_weight="1"
            android:gravity="center"
            android:text="想法"

            android:button="@null"/>

    </RadioGroup>

    <FrameLayout

        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/fcontent"
        ></FrameLayout>

</RelativeLayout>

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import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;

import android.view.View;
import android.widget.FrameLayout;
import android.widget.RadioButton;
import android.widget.RadioGroup;

public class MainActivity extends AppCompatActivity {

    private FrameLayout fcontent;
    private RadioButton rb_index;
    private RadioButton rb_main;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        fcontent = findViewById(R.id.fcontent);
        RadioGroup radioGroup=findViewById(R.id.rg);
        rb_index = findViewById(R.id.rb_index);
        rb_main = findViewById(R.id.rb_mind);
        radioGroup.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() {
            @Override
            public void onCheckedChanged(RadioGroup radioGroup, int i) {
                switch (i){
                    case R.id.rb_index:
                        getSupportFragmentManager().beginTransaction().replace(R.id.fcontent,new Fragment_01()).commit();
                        break;
                    case R.id.rb_mind:
                        getSupportFragmentManager().beginTransaction().replace(R.id.fcontent,new MindFragment()).commit();
                        break;
                }
            }
        });

        //设置初始fragment页面
        getSupportFragmentManager().beginTransaction().
                replace(R.id.fcontent,new Fragment_01()).commit();

    }}