单选框 RadioButton

<?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">


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

        <RadioButton
            android:id="@+id/rbt"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:textSize="25dp"
            android:text="男"
            />
        <RadioButton
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:textSize="25dp"
            android:text="女"
            />
    </RadioGroup>

        <TextView
            android:id="@+id/tv"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:textSize="25dp"
            />

</LinearLayout>

package com.iang.buttonclick;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.RadioGroup;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity  {

    private RadioGroup radioGroup;
    private TextView textView;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

       radioGroup= (RadioGroup)findViewById(R.id.rdg);
        textView=(TextView) findViewById(R.id.tv);
        radioGroup.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() {
            @Override
            public void onCheckedChanged(RadioGroup group, int checkedId) {
                if (checkedId==R.id.rbt)
                    textView.setText("您的性别是:男");
                else
                    textView.setText("您的性别是:女");
            }
        });

    }
}