如何使用while循环，for循环替换此do while循环。 import javax.swing.JOptionPane； 公共类样本1{ 公共静态void main（字符串[]args）{ 双延迟； 国际日； 字符串标准容差，标准日期； 做{ strdAmount=JOptionPane.showInputDialog（空，“请输入每日津贴$：（>0）”， “津贴”，作业窗格。信息（信息）； dAllowance=Double.parseDouble（标准容差）； if（dAllowance

我已经将第一个do while循环转换为for循环，代码如下

编辑：

我认为下面的版本比上一个版本稍微好一点：

import javax.swing.JOptionPane;


public class SampleLT1 {

    public static void main(String[] args) {
        double dAllowance;
        int days;

        String strDAllowance, strDays;
        do{
            strDAllowance = JOptionPane.showInputDialog(null,"Please enter Daily Allowance $:(>0)",
                "Allowance", JOptionPane.INFORMATION_MESSAGE);
            dAllowance = Double.parseDouble(strDAllowance);
            if (dAllowance<0) System.out.println("Daily Allowance shoould be >0. Please enter again.");
            if (dAllowance==0) {//if enter daily Allowance as 0, exit the program
                System.out.println("Thank you for using Allowance Calculating Application.");
                System.exit(0);
            }
        }while (dAllowance<0);//if daily allowance is smaller than 0, enter again

        do{
            strDays = JOptionPane.showInputDialog(null,"Please enter No. of working days: (>0 and <42)",
                "Allowance", JOptionPane.INFORMATION_MESSAGE);
            days = Integer.parseInt(strDays);
            if(days<0 || days>42) System.out.println("No. of working days should >0 and <42. Please enter again.");
            if (days==0) {//enter 0 to quit the program
                System.out.println("Thank you for using Allowance Calculating Application.");
                System.exit(0);
            }
        }while (days<0 || days>42);//if days <0 or >42, enter days again
        System.out.println("For an internship student who worked "+days +" days with daily allowance $"+dAllowance+", his total allowance is $"+calAllowance(dAllowance,days));
        System.exit(0);
    }

    public static double calAllowance(double dailyAllowance, int noOfDays){
        return dailyAllowance * noOfDays;//calculate and return total allowance
    }
    }

import javax.swing.JOptionPane；
公共类样本1{
公共静态void main（字符串[]args）{
双dAllowance=0；
国际日；
字符串标准容差，标准日期；
对于（inti=-1；i0）i++；
}//如果每日津贴小于0，请重新输入
做{
strDays=JOptionPane.showInputDialog（null，“请输入工作日数：（>0和0，并且您不需要在for循环中输入任何内容。完全空的for循环
for（；）
与
while（true）
相同。任何while循环都可以转换为for循环：

import javax.swing.JOptionPane;

public class SampleLT1 {

    public static void main(String[] args) {
        double dAllowance = 0;
        int days;

        String strDAllowance, strDays;
        for(int i =-1;i<0;){
            strDAllowance = JOptionPane.showInputDialog(null,"Please enter Daily Allowance $:(>0)",
                "Allowance", JOptionPane.INFORMATION_MESSAGE);
            dAllowance = Double.parseDouble(strDAllowance);
            if (dAllowance<0){ 
                System.out.println("Daily Allowance shoould be >0. Please enter again.");
            }
            if (dAllowance==0) {//if enter daily Allowance as 0, exit the program
                System.out.println("Thank you for using Allowance Calculating Application.");
                System.exit(0);
            }
            if (dAllowance>0) i++;
        }//if daily allowance is smaller than 0, enter again

        do{
            strDays = JOptionPane.showInputDialog(null,"Please enter No. of working days: (>0 and <42)",
                "Allowance", JOptionPane.INFORMATION_MESSAGE);
            days = Integer.parseInt(strDays);
            if(days<0 || days>42) System.out.println("No. of working days should >0 and <42. Please enter again.");
            if (days==0) {//enter 0 to quit the program
                System.out.println("Thank you for using Allowance Calculating Application.");
                System.exit(0);
            }
        }while (days<0 || days>42);//if days <0 or >42, enter days again
        System.out.println("For an internship student who worked "+days +" days with daily allowance $"+dAllowance+", his total allowance is $"+calAllowance(dAllowance,days));
        System.exit(0);
    }

    public static double calAllowance(double dailyAllowance, int noOfDays){
        return dailyAllowance * noOfDays;//calculate and return total allowance
    }
    }

while (
    ( dAllowance = Double.parseDouble(
        JOptionPane.showInputDialog(
            null,
            "Please enter Daily Allowance $:(>0)",
            "Allowance",
            JOptionPane.INFORMATION_MESSAGE)
    ) ) < 0) {
        System.out.println("Daily Allowance shoould be >0. Please enter again.");
}

if (dAllowance == 0) {
    System.out.println(
        "Thank you for using Allowance Calculating Application.");
    System.exit(0);
}

如果你真的想深入研究“什么是有效的循环逻辑”，请考虑下面的内容：

double dAllowance;
String strDAllowance;

for ( ; ; ) {
    strDAllowance = JOptionPane.showInputDialog(/* ~~~ */);

    try {
        dAllowance = Double.parseDouble(strDAllowance);

        if (dAllowance > 0) {
            break;

        } else if (dAllowance == 0) {
            System.exit(0);
        }
    } catch (NumberFormatException e) {}

    /* notify and automatically continues */
}

while(
（dAllowance=Double.parseDouble(
JOptionPane.showInputDialog(
无效的
“请输入每日津贴$：（>0）”，
“津贴”，
JOptionPane.INFORMATION（消息）
) ) < 0) {
System.out.println（“每日津贴应大于0，请重新输入”）；
}
如果（dAllowance==0）{
System.out.println(
“感谢您使用津贴计算应用程序。”）；
系统出口（0）；
}

请注意，为了可读性，我只在while循环中加了大括号。大括号应该是不必要的。当然，这也可以转化为for循环：

import javax.swing.JOptionPane;

public class SampleLT1 {

    public static void main(String[] args) {
        double dAllowance = 0;
        int days;

        String strDAllowance, strDays;
        for(int i =-1;i<0;){
            strDAllowance = JOptionPane.showInputDialog(null,"Please enter Daily Allowance $:(>0)",
                "Allowance", JOptionPane.INFORMATION_MESSAGE);
            dAllowance = Double.parseDouble(strDAllowance);
            if (dAllowance<0){ 
                System.out.println("Daily Allowance shoould be >0. Please enter again.");
            }
            if (dAllowance==0) {//if enter daily Allowance as 0, exit the program
                System.out.println("Thank you for using Allowance Calculating Application.");
                System.exit(0);
            }
            if (dAllowance>0) i++;
        }//if daily allowance is smaller than 0, enter again

        do{
            strDays = JOptionPane.showInputDialog(null,"Please enter No. of working days: (>0 and <42)",
                "Allowance", JOptionPane.INFORMATION_MESSAGE);
            days = Integer.parseInt(strDays);
            if(days<0 || days>42) System.out.println("No. of working days should >0 and <42. Please enter again.");
            if (days==0) {//enter 0 to quit the program
                System.out.println("Thank you for using Allowance Calculating Application.");
                System.exit(0);
            }
        }while (days<0 || days>42);//if days <0 or >42, enter days again
        System.out.println("For an internship student who worked "+days +" days with daily allowance $"+dAllowance+", his total allowance is $"+calAllowance(dAllowance,days));
        System.exit(0);
    }

    public static double calAllowance(double dailyAllowance, int noOfDays){
        return dailyAllowance * noOfDays;//calculate and return total allowance
    }
    }

while (
    ( dAllowance = Double.parseDouble(
        JOptionPane.showInputDialog(
            null,
            "Please enter Daily Allowance $:(>0)",
            "Allowance",
            JOptionPane.INFORMATION_MESSAGE)
    ) ) < 0) {
        System.out.println("Daily Allowance shoould be >0. Please enter again.");
}

if (dAllowance == 0) {
    System.out.println(
        "Thank you for using Allowance Calculating Application.");
    System.exit(0);
}

用于（；
（dAllowance=Double.parseDouble(
JOptionPane.showInputDialog(
无效的
“请输入每日津贴$：（>0）”，
“津贴”，
JOptionPane.INFORMATION（消息）
) ) < 0;
System.out.println（“每日津贴应大于0，请重新输入”）
)；//循环的
是如何工作的？涉及哪些组件？可能会有帮助。我建议你用一些简单的例子（例如打印出数字）来处理循环。它们不难理解，但所有Swing代码附带的复杂性使“玩”更难“用你的例子。啊，非常感谢！在再次尝试之前，我会尝试其他循环的例子！非常感谢！虽然我仍然不确定循环，但我会尽量吸收！没问题。我已经编辑了我认为更好的答案。这是（；I<10；）的
）
很有用：我不知道你能做到这一点。（+1）。@KnockFall没问题。如果问题已经解决，一定要标记它。：@bluesh34确实，你可以或多或少地将任何你想要的东西放入for循环中。
while (
    ( dAllowance = Double.parseDouble(
        JOptionPane.showInputDialog(
            null,
            "Please enter Daily Allowance $:(>0)",
            "Allowance",
            JOptionPane.INFORMATION_MESSAGE)
    ) ) < 0) {
        System.out.println("Daily Allowance shoould be >0. Please enter again.");
}

if (dAllowance == 0) {
    System.out.println(
        "Thank you for using Allowance Calculating Application.");
    System.exit(0);
}

for (;
    ( dAllowance = Double.parseDouble(
        JOptionPane.showInputDialog(
            null,
            "Please enter Daily Allowance $:(>0)",
            "Allowance",
            JOptionPane.INFORMATION_MESSAGE)
    ) ) < 0;
        System.out.println("Daily Allowance shoould be >0. Please enter again.")
); // <- no body necessary