实现Android单选框的监听

以下是java文件

package part1.bw.com.test02;

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

public class test7Activity extends AppCompatActivity {
RadioGroup gp;
RadioButton nan;
RadioButton nv;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_test7);
nan=findViewById(R.id.nan);
nv=findViewById(R.id.nv);
gp=findViewById(R.id.gp);
gp.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() {

        @Override
        public void onCheckedChanged(RadioGroup group, int checkedId) {
            if(checkedId==nan.getId()){
                Toast.makeText(test7Activity.this, "男", Toast.LENGTH_SHORT).show();
            }else{
                Toast.makeText(test7Activity.this, "女", Toast.LENGTH_SHORT).show();
            }
        }
    });
}

}