Android学习笔记篇2. 单选按钮、复选按钮

单选按钮

在XML里写一组单选按钮（2个）+ 一个文本（用于提示）：

在Java中编写代码

package com.example.no_2;

import androidx.appcompat.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 radioGroup, int i) {
                // 判断被点击的RadioButton
                if (i == R.id.rbtn) {
                    textView.setText("您的性别是：男");
                } else {
                    textView.setText("您的性别是：女");
                }
            }
        });
    }
}

运行，点击按钮，在底下提示相应信息：

复选按钮

在XML里写一组复选按钮 + 两个提示文本 + 一个显示输出文本

在Java中编写代码，利用TextView提示哪一个复选框被选择：

package com.example.no_2;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.widget.CheckBox;
import android.widget.CompoundButton;
import android.widget.RadioGroup;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity implements CompoundButton.OnCheckedChangeListener {

    private TextView hobby;
    private String hobbys;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        
        CheckBox shuttlecock = (CheckBox) findViewById(R.id.shuttlecock);
        CheckBox basketball = (CheckBox) findViewById(R.id.basketball);
        CheckBox pingpong = (CheckBox) findViewById(R.id.pingpong);
        shuttlecock.setOnCheckedChangeListener(this);
        basketball.setOnCheckedChangeListener(this);
        pingpong.setOnCheckedChangeListener(this);
        hobby = (TextView) findViewById(R.id.hobby);
        hobbys = new String();
    }

    @Override
    public void onCheckedChanged(CompoundButton compoundButton, boolean b) {
        String motion = compoundButton.getText().toString();
        
        if (b) {
            if (!hobbys.contains(motion)) {
                hobbys = hobbys + motion;
                hobby.setText(hobbys);
            }
        } else {
            if (hobbys.contains(motion)) {
                hobbys = hobbys.replace(motion, "");
                hobby.setText(hobbys);
            }
        }
    }
}

运行，在底下提示对应信息：