Fragment的使用

private RadioGroup rg;
private RadioButton bt1,bt2,bt3,bt4;
@Nullable
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
    View view = inflater.inflate(R.layout.mainfragment01, container, false);
     bt1 = view.findViewById(R.id.bt1);
     bt2 = view.findViewById(R.id.bt2);
     bt3 = view.findViewById(R.id.bt3);
     bt4 = view.findViewById(R.id.bt4);
    rg = view.findViewById(R.id.rg);
    getActivity().getSupportFragmentManager().beginTransaction().replace(R.id.frag,new Fragment01()).commit();
    bt1.setTextColor(Color.RED);
    bt2.setTextColor(Color.BLACK);
    bt3.setTextColor(Color.BLACK);
    bt4.setTextColor(Color.BLACK);
    rg.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() {
        @Override
        public void onCheckedChanged(RadioGroup radioGroup, @IdRes int i) {
            switch (i){
                case R.id.bt1:
                    getActivity().getSupportFragmentManager().beginTransaction().replace(R.id.frag,new Fragment01()).commit();
                    bt1.setTextColor(Color.RED);
                    bt2.setTextColor(Color.BLACK);
                    bt3.setTextColor(Color.BLACK);
                    bt4.setTextColor(Color.BLACK);
                    break;
                case R.id.bt2:
                    getActivity().getSupportFragmentManager().beginTransaction().replace(R.id.frag,new Fragment02()).commit();
                    bt1.setTextColor(Color.BLACK);
                    bt2.setTextColor(Color.RED);
                    bt3.setTextColor(Color.BLACK);
                    bt4.setTextColor(Color.BLACK);
                    break;
                case R.id.bt3:
                    getActivity().getSupportFragmentManager().beginTransaction().replace(R.id.frag,new Fragment03()).commit();
                    bt1.setTextColor(Color.BLACK);
                    bt2.setTextColor(Color.BLACK);
                    bt3.setTextColor(Color.RED);
                    bt4.setTextColor(Color.BLACK);
                    break;
                case R.id.bt4:
                    getActivity().getSupportFragmentManager().beginTransaction().replace(R.id.frag,new Fragment04()).commit();
                    bt1.setTextColor(Color.BLACK);
                    bt2.setTextColor(Color.BLACK);
                    bt3.setTextColor(Color.BLACK);
                    bt4.setTextColor(Color.RED);
                    break;
            }
        }
    });


    return view;
}





<?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">

    <FrameLayout
        android:id="@+id/frag"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_weight="9" />



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

        <RadioButton
            android:id="@+id/bt1"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:layout_weight="1"
            android:button="@null"
            android:gravity="center"
            android:text="首页"
            android:textSize="20sp" />

        <RadioButton
            android:id="@+id/bt2"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:layout_weight="1"
            android:button="@null"
            android:gravity="center"
            android:text="自选"
            android:textSize="20sp" />

        <RadioButton
            android:id="@+id/bt3"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:layout_weight="1"
            android:button="@null"
            android:gravity="center"
            android:text="行情"
            android:textSize="20sp" />

        <RadioButton
            android:id="@+id/bt4"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:layout_weight="1"
            android:button="@null"
            android:gravity="center"
            android:text="咨询"
            android:textSize="20sp" />

    </RadioGroup>

</LinearLayout>