RadioGroup折扣计算异常：0%折扣功能失效求助

我正在开发一个咖啡馆菜单计算项目，使用RadioGroup区分0%（现金支付）和10%（信用卡支付）折扣。选择10%折扣的单选按钮时代码运行正常，但选择0%折扣的单选按钮时，计算结果仍与10%折扣一致，功能失效。

原代码 #

package com.example.fo_liaharsono_proj_cafestekom;

import android.os.Bundle;
import android.app.Activity;
import android.view.View;
import android.widget.Button;
import android.widget.CheckBox;
import android.widget.RadioButton;
import android.widget.RadioGroup;
import android.widget.TextView;

public class MainActivity extends Activity {
    TextView edHrgAyamG,edHrgAyamC,edHrgKentang,edHrgSoft,edHrgAir,edSubTotal,edStatus,edBayar;
    CheckBox cbAyamG,cbAyamC,cbKentang,cbSoft,cbAir;
    RadioGroup radioGroup1;
    RadioButton rgTunai,rgCredit;
    Button btnPesan;
    
    private boolean checked;
    private double dSubTotal;
    private double dBayar;
    private double dHrgAyamG;
    private double dHrgAyamC;
    private double dHrgKentang;
    private double dHrgSoft;
    private double dHrgAir;
    private double Diskon;
    

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        edHrgAyamG = (TextView)findViewById(R.id.edHrgAyamG);
        edHrgAyamC = (TextView)findViewById(R.id.edHrgAyamC);
        edHrgKentang = (TextView)findViewById(R.id.edHrgKentang);
        edHrgSoft = (TextView)findViewById(R.id.edHrgSoft);
        edHrgAir = (TextView)findViewById(R.id.edHrgAir);
        edSubTotal = (TextView)findViewById(R.id.edSubTotal);
        edStatus = (TextView)findViewById(R.id.edStatus);
        edBayar = (TextView)findViewById(R.id.edBayar);
        
        cbAyamG = (CheckBox)findViewById(R.id.cbAyamG);
        cbAyamC = (CheckBox)findViewById(R.id.cbAyamC);
        cbKentang = (CheckBox)findViewById(R.id.cbKentang);
        cbSoft = (CheckBox)findViewById(R.id.cbSoft);
        cbAir = (CheckBox)findViewById(R.id.cbAir);
        
        radioGroup1 = (RadioGroup)findViewById(R.id.radioGroup1);
        rgTunai = (RadioButton)findViewById(R.id.rgTunai);
        rgCredit = (RadioButton)findViewById(R.id.rgCredit);
        
        btnPesan = (Button)findViewById(R.id.btnPesan);
    
radioGroup1.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() {
    
    @Override
    public void onCheckedChanged(RadioGroup arg0, int arg1) {
        // TODO Auto-generated method stub
        if(rgTunai.isChecked())
            edStatus.setText("Pembayaran Tunai Diskon 0%");
        btnPesan.setOnClickListener(new View.OnClickListener() {
            
            @Override
            public void onClick(View arg0) {
                // TODO Auto-generated method stub
                dSubTotal = (dHrgAyamG)+(dHrgAyamC)+(dHrgKentang)+(dHrgSoft)+(dHrgAir);
                Diskon = (dSubTotal*0)/100;
                dBayar = (dSubTotal-Diskon)*1000;
                edBayar.setText("Rp.  "+dBayar);
            }
        });
        if(rgCredit.isChecked())
            edStatus.setText("Pembayaran Credit Diskon 10%");
        btnPesan.setOnClickListener(new View.OnClickListener() {
            
            @Override
            public void onClick(View arg0) {
                // TODO Auto-generated method stub
                dSubTotal = (dHrgAyamG)+(dHrgAyamC)+(dHrgKentang)+(dHrgSoft)+(dHrgAir);
                Diskon = (dSubTotal*10)/100;
                dBayar = (dSubTotal-Diskon)*1000;
                edBayar.setText("Rp. "+dBayar);
            }
            });  
            }
        });
        };          
        
    
    public void KlikCheckBox(View v){
        checked = ((CheckBox)v).isChecked();
        switch (v.getId()){
        case R.id.cbAyamG:
            if(checked)edHrgAyamG.setText("15.000");
            else edHrgAyamG.setText("0");
            break;
        case R.id.cbAyamC:
            if(checked)edHrgAyamC.setText("12.000");
            else edHrgAyamC.setText("0");
            break;
        case R.id.cbKentang:
            if(checked)edHrgKentang.setText("10.000");
            else edHrgKentang.setText("0");
            break;
        case R.id.cbSoft:
            if(checked)edHrgSoft.setText("5.000");
            else edHrgSoft.setText("0");
            break;
        case R.id.cbAir:
            if(checked)edHrgAir.setText("3.000");
            else edHrgAir.setText("0");
            break;
        }
        dHrgAyamG = Double.parseDouble(edHrgAyamG.getText().toString());
        dHrgAyamC = Double.parseDouble(edHrgAyamC.getText().toString());
        dHrgKentang = Double.parseDouble(edHrgKentang.getText().toString());
        dHrgSoft = Double.parseDouble(edHrgSoft.getText().toString());
        dHrgAir = Double.parseDouble(edHrgAir.getText().toString());
        
        dSubTotal = ((dHrgAyamG)+(dHrgAyamC)+(dHrgKentang)+(dHrgSoft)+(dHrgAir))*1000;
        edSubTotal.setText(""+dSubTotal);
    }
}

问题原因 #

• 重复设置点击监听器：每次切换RadioButton时，都会给btnPesan新增一个点击监听器，后面的监听器会覆盖前面的。比如先选信用卡再选现金，最后生效的是信用卡的监听器，导致计算结果始终是10%折扣。
• 依赖TextView文本解析价格，容易出现格式错误；折扣计算逻辑重复，代码冗余。

修复方案 #

将按钮点击监听器从RadioGroup切换事件中移出，只初始化一次，点击时根据当前选中的RadioButton判断折扣比例；同时优化价格存储逻辑，直接用变量维护价格，避免解析TextView文本。

修复后的代码 #

package com.example.fo_liaharsono_proj_cafestekom;

import android.os.Bundle;
import android.app.Activity;
import android.view.View;
import android.widget.Button;
import android.widget.CheckBox;
import android.widget.RadioButton;
import android.widget.RadioGroup;
import android.widget.TextView;

public class MainActivity extends Activity {
    TextView edSubTotal, edStatus, edBayar;
    CheckBox cbAyamG, cbAyamC, cbKentang, cbSoft, cbAir;
    RadioGroup radioGroup1;
    RadioButton rgTunai, rgCredit;
    Button btnPesan;
    
    // 直接定义商品价格常量，避免依赖TextView
    private static final double PRICE_AYAM_G = 15.000;
    private static final double PRICE_AYAM_C = 12.000;
    private static final double PRICE_KENTANG = 10.000;
    private static final double PRICE_SOFT = 5.000;
    private static final double PRICE_AIR = 3.000;

    private double dHrgAyamG = 0;
    private double dHrgAyamC = 0;
    private double dHrgKentang = 0;
    private double dHrgSoft = 0;
    private double dHrgAir = 0;
    private double dSubTotal;
    private double dBayar;

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

        // 初始化控件
        edSubTotal = findViewById(R.id.edSubTotal);
        edStatus = findViewById(R.id.edStatus);
        edBayar = findViewById(R.id.edBayar);
        
        cbAyamG = findViewById(R.id.cbAyamG);
        cbAyamC = findViewById(R.id.cbAyamC);
        cbKentang = findViewById(R.id.cbKentang);
        cbSoft = findViewById(R.id.cbSoft);
        cbAir = findViewById(R.id.cbAir);
        
        radioGroup1 = findViewById(R.id.radioGroup1);
        rgTunai = findViewById(R.id.rgTunai);
        rgCredit = findViewById(R.id.rgCredit);
        
        btnPesan = findViewById(R.id.btnPesan);

        // RadioGroup切换监听，只更新状态文本
        radioGroup1.setOnCheckedChangeListener((arg0, arg1) -> {
            if (rgTunai.isChecked()) {
                edStatus.setText("Pembayaran Tunai Diskon 0%");
            } else if (rgCredit.isChecked()) {
                edStatus.setText("Pembayaran Credit Diskon 10%");
            }
        });

        // 按钮点击监听只设置一次，点击时判断当前选中的RadioButton
        btnPesan.setOnClickListener(v -> {
            calculateSubTotal();
            double discountRate = rgTunai.isChecked() ? 0 : 10;
            dBayar = (dSubTotal - (dSubTotal * discountRate / 100)) * 1000;
            edBayar.setText("Rp. " + dBayar);
        });

        // 默认选中现金支付
        rgTunai.setChecked(true);
        edStatus.setText("Pembayaran Tunai Diskon 0%");
    }

    // 计算小计
    private void calculateSubTotal() {
        dSubTotal = dHrgAyamG + dHrgAyamC + dHrgKentang + dHrgSoft + dHrgAir;
        edSubTotal.setText(String.valueOf(dSubTotal * 1000));
    }

    public void KlikCheckBox(View v) {
        boolean checked = ((CheckBox) v).isChecked();
        switch (v.getId()) {
            case R.id.cbAyamG:
                dHrgAyamG = checked ? PRICE_AYAM_G : 0;
                break;
            case R.id.cbAyamC:
                dHrgAyamC = checked ? PRICE_AYAM_C : 0;
                break;
            case R.id.cbKentang:
                dHrgKentang = checked ? PRICE_KENTANG : 0;
                break;
            case R.id.cbSoft:
                dHrgSoft = checked ? PRICE_SOFT : 0;
                break;
            case R.id.cbAir:
                dHrgAir = checked ? PRICE_AIR : 0;
                break;
        }
        calculateSubTotal();
    }
}

内容的提问来源于stack exchange，提问作者Lia Harsono