为啥我的代码的最后一行没有打印？另外，我将数字四舍五入到小数点后两位的最简单方法是啥？ [复制]

Posted 2023-04-13

【中文标题】为啥我的代码的最后一行没有打印？另外，我将数字四舍五入到小数点后两位的最简单方法是啥？ [复制]

【英文标题】：Why is the last line of my code not printing? Also, what's the simplest way for me to round numbers to 2 decimals? [duplicate]为什么我的代码的最后一行没有打印？另外，我将数字四舍五入到小数点后两位的最简单方法是什么？ [复制]

【发布时间】：2016-10-14 01:02:24

【问题描述】：

在运行我的程序时，显示每年 gas 费用的最后一行没有显示...我做错了什么？还需要一些帮助将数字四舍五入到小数点后 2 位... 我尝试实施一些策略，但没有一个奏效。 任何帮助表示赞赏！

public class GasExpenses 
public static void main(String[] args) 

//Use scanner in order to retrieve user input.
Scanner keyboard= new Scanner(System.in);

//Declare variables.
int milesPerWeek;
double milesPerGallon,costOfGas;


System.out.println("GAS EXPENSES"); 
//Get user input.
System.out.println("How many miles do you drive a week?");
milesPerWeek = keyboard.nextInt();

//Get user input.
System.out.println("How many miles per gallon does your auto get?");
milesPerGallon=keyboard.nextDouble();

//Get user input.
System.out.println("What is the current cost of gas?");
costOfGas=keyboard.nextDouble();

//Calculate miles per year.
int milesPerYear=(milesPerWeek*52);
//Display calculated yearly mileage.
System.out.println("At " + milesPerWeek + "miles per week, you travel "+
milesPerYear + " miles per year.");

//Calculate and display calculated weekly & yearly gallons of gas used.
double gallonsPerWeek=(milesPerWeek/milesPerGallon); 
System.out.println("Gallons per week:" + gallonsPerWeek);
double gallonsPerYear=(gallonsPerWeek*52);
System.out.println("Gallons per year:" + gallonsPerYear);

//Calculate and display calculated weekly & yearly gas expense.
System.out.println("With gas at $" +costOfGas + " per gallon, you will
spend: ");
double weeklyGasExpense=(costOfGas*milesPerWeek);
System.out.println("Gas expense per week: $" +weeklyGasExpense);
double yearlyGasExpense=(costOfGas*milesPerYear);
System.out.println("Gas expense per year: $" +yearlyGasExpense);

//Calculate and display calculated weekly & yearly gas expense based on
increased gas price.
double costIncrease= (costOfGas+1);
System.out.println("If gas goes up by one dollar per gallon to $" +
costIncrease +(" per gallon, you will spend:"));
double weeklyIncreasedGas=(costIncrease*milesPerWeek);
double yearlyIncreasedGas=(costIncrease*milesPerYear);
System.out.println("Gas expense per week : $" +weeklyIncreasedGas);
System.out.print("Gas expense per year : $" +yearlyIncreasedGas);

【问题讨论】：

您是否遗漏了代码的结尾？看不到没有终止s

double round = Math.round(a * 100.0) / 100.0; 你的第二个问题

请仔细阅读minimal reproducible example 指南，了解应作为示例代码发布的内容，并针对每个帖子提出一个 问题。 （请注意，其他人之前可能已经尝试过以这种方式格式化数字 - 请务必先搜索）。

我没有粘贴它们...让我编辑。不过，它们在原始代码中。

【参考方案1】：

在代码末尾运行 system.out.flush() 以确保打印所有内容。

对于四舍五入，你可以试试这个答案round up to 2 decimal places in java?

【参考方案2】：

对于第一个问题，鉴于您的代码，这一行对我有用：

System.out.print("Gas expense per year : $" +yearlyIncreasedGas);

第二次这样做：

double number = 111.12345;
double result = Math.round(number * 100.0) / 100.0;