如何让这个java代码回到代码中的某一点？

Question

你可能会说,这是一个计算器.这是我用Java制作的第二个程序,除了机器人代码.我对Java很新,所以我对此并不了解.我希望能够在回答问题之后回到菜单(第19-27行).如果我能做到这一点,我会把M之类的东西放到菜单上,或者E放回答案之后退出.我想要它,所以如果他们把M,它将返回到那些代码行,以便能够重新开始,而不是重新启动程序.谢谢,马特.

public class Calculator {
public static void main(String[] args) {
    System.out.println("Calculator");
    System.out.println("----------");
    System.out.println("Press 1 for addition");
    System.out.println("Press 2 for subtraction");
    System.out.println("Press 3 for multiplication");
    System.out.println("Press 4 for division");
    int Menu;
    Scanner menu_scanner = new Scanner(System.in);
    Menu = menu_scanner.nextInt();
    if (Menu == 1){
        System.out.println("");
        System.out.println("");
        System.out.println("");
        System.out.println("");
        System.out.println("");
        System.out.println("");
        System.out.println("");
        System.out.println("");
        System.out.println("");
        System.out.println("");
        System.out.println("Please enter the first number in the problem");
        System.out.println("--------------------------------------------");
        double iAddition1;
        double iAddition2;
        double aAddition;
        Scanner sAddition1 = new Scanner(System.in);
        iAddition1 = sAddition1.nextDouble();
        System.out.println("Please enter the second number in the problem");
        System.out.println("---------------------------------------------");
        Scanner sAddition2 = new Scanner(System.in);
        iAddition2 = sAddition2.nextDouble();
        aAddition = iAddition1 + iAddition2;
        System.out.println("The answer to " + iAddition1 + " + " + iAddition2 + " = " + aAddition);
    }
    if (Menu == 2){
        System.out.println("");
        System.out.println("");
        System.out.println("");
        System.out.println("");
        System.out.println("");
        System.out.println("");
        System.out.println("");
        System.out.println("");
        System.out.println("");
        System.out.println("");
        System.out.println("Please enter the first number in the problem");
        System.out.println("--------------------------------------------");
        double iSubtraction1;
        Scanner sSubtraction1 = new Scanner(System.in);
        iSubtraction1 = sSubtraction1.nextDouble();
        System.out.println("Please enter the second number in the problem");
        System.out.println("---------------------------------------------");
        double iSubtraction2;
        Scanner sSubtraction2 = new Scanner(System.in);
        iSubtraction2 = sSubtraction2.nextDouble();
        double aSubtraction = iSubtraction1 - iSubtraction2;
        System.out.println("The answer to " + iSubtraction1 + " - " + iSubtraction2 + " = " + aSubtraction);
    }
    if (Menu == 3){
        System.out.println("");
        System.out.println("");
        System.out.println("");
        System.out.println("");
        System.out.println("");
        System.out.println("");
        System.out.println("");
        System.out.println("");
        System.out.println("");
        System.out.println("");
        System.out.println("Please enter the first number in the problem");
        System.out.println("--------------------------------------------");
        double iMultiplication1;
        double iMultiplication2;
        Scanner sMultiplication1 = new Scanner(System.in);
        iMultiplication1 = sMultiplication1.nextDouble();
        System.out.println("Please enter the second number in the problem");
        System.out.println("---------------------------------------------");
        Scanner sMultiplication2 = new Scanner(System.in);
        iMultiplication2 = sMultiplication2.nextDouble();
        double aMultiplication = iMultiplication1 * iMultiplication2;
        System.out.println("The answer to " + iMultiplication1 + " * " + iMultiplication2 + " = " + aMultiplication);
    }
    if (Menu == 4){
        System.out.println("");
        System.out.println("");
        System.out.println("");
        System.out.println("");
        System.out.println("");
        System.out.println("");
        System.out.println("");
        System.out.println("");
        System.out.println("");
        System.out.println("");
        System.out.println("Please enter the first number in the problem");
        System.out.println("--------------------------------------------");
        Scanner sDivision1 = new Scanner(System.in);
        double iDivision1;
        iDivision1 = sDivision1.nextDouble();
        System.out.println("Please enter the second number in the problem");
        System.out.println("---------------------------------------------");
        Scanner sDivision2 = new Scanner(System.in);
        double iDivision2;
        iDivision2 = sDivision1.nextDouble();
        double aDivision = iDivision1 / iDivision2;
        System.out.println("The answer to " + iDivision1 + " / " + iDivision2 + " = " + aDivision);
    }
}    
}

Answer 1

你正在寻找一个循环.可能是一个循环.

Answer 2

一个while与您选择的条件下环(如检查一定值时没有遇到),或for具有一定的迭代次数的循环,如果你满足于做的一组操作,比方说,例如10倍.

一种解决方案是Menu = menu_scanner.nextInt在while循环之后将整个代码块包装起来while(Menu < 5),并提供另一个选项5以退出程序.

基本上,您需要从指南中了解Java中的控件结构,例如http://docs.oracle.com/javase/tutorial/java/nutsandbolts/flow.html