Android单选按钮radio练习1

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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=".RadioTest1"
    android:orientation="vertical">

    <RadioGroup
        android:id="@+id/radiogroup1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
    >
        <RadioButton
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="男"></RadioButton>
        <RadioButton
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="女"></RadioButton>
        <RadioButton
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="保密"></RadioButton>
    </RadioGroup>

    <Button
        android:id="@+id/btn_radio"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="提交"
        ></Button>
</LinearLayout>

public class RadioTest1 extends AppCompatActivity {

    private RadioGroup rg;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_radio_test1);

        rg = findViewById(R.id.radiogroup1);//找到单选按钮组
        rg.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() {
            @Override
            public void onCheckedChanged(RadioGroup radioGroup, int checkdId) {
                RadioButton r = findViewById(checkdId);
                Toast.makeText(RadioTest1.this, "性别:"+r.getText(), Toast.LENGTH_SHORT).show();
            }
        });

        Button btn_radio = findViewById(R.id.btn_radio);
        btn_radio.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                for (int i = 0; i < rg.getChildCount() ; i++) {
                    RadioButton r = (RadioButton) rg.getChildAt(i);
                    if (r.isChecked()) {
                        Toast.makeText(RadioTest1.this, r.getText(), Toast.LENGTH_SHORT).show();
                    }
                }
            }
        });

    }
}