-1

如果这是一个奇怪的问题，我很抱歉，但我刚刚开始 OOP 并遇到了这个问题，因为我应该制作一个简单的菜单驱动数学程序。我清除了编译器给我的所有错误，但现在它给了我大约 14 个新错误，其中大部分被描述为“找不到符号”。这是我的代码：

import java.util.Scanner;


public class MathMenu
{


//MENU METHOD
private static void menu(String args[])
{
int choice;

System.out.printf("Enter '1' to add");
System.out.printf("Enter '2' to subtract");
System.out.printf("Enter '3' to exit");

System.out.printf("\nPlease enter your choice: ");


choice=input.nextInt();

if (choice==1)
sum(n,m);

if (choice==2)
dif(n,m);

else if(choice==3)
return;

}



//SUM
private static int sum(int a, int b)
{
return n+m;
}


//DIFFERENCE 
private static int dif(int a, int b)
{
if(n<m)
return m-n;

else
return n-m;
}





public static void main(String args[])
{


int n=15;
int m=8;

Scanner input = new Scanner(System.in);

menu();

}


}

这是新的编译器输出：

Microsoft Windows [Version 6.1.7601]
Copyright (c) 2009 Microsoft Corporation.  All rights reserved.

C:\Users\Shahraiz Tabassam>cd c:\java\bin

c:\java\bin>javac MathMenu.java
MathMenu.java:7: error: no suitable constructor found for Scanner()
private static Scanner input = new Scanner();
                               ^
    constructor Scanner.Scanner(ReadableByteChannel,String) is not applicable
      (actual and formal argument lists differ in length)
    constructor Scanner.Scanner(ReadableByteChannel) is not applicable
      (actual and formal argument lists differ in length)
    constructor Scanner.Scanner(String) is not applicable
      (actual and formal argument lists differ in length)
    constructor Scanner.Scanner(Path,Charset) is not applicable
      (actual and formal argument lists differ in length)
    constructor Scanner.Scanner(Path,String) is not applicable
      (actual and formal argument lists differ in length)
    constructor Scanner.Scanner(Path) is not applicable
      (actual and formal argument lists differ in length)
    constructor Scanner.Scanner(File,CharsetDecoder) is not applicable
      (actual and formal argument lists differ in length)
    constructor Scanner.Scanner(File,String) is not applicable
      (actual and formal argument lists differ in length)
    constructor Scanner.Scanner(File) is not applicable
      (actual and formal argument lists differ in length)
    constructor Scanner.Scanner(InputStream,String) is not applicable
      (actual and formal argument lists differ in length)
    constructor Scanner.Scanner(InputStream) is not applicable
      (actual and formal argument lists differ in length)
    constructor Scanner.Scanner(Readable) is not applicable
      (actual and formal argument lists differ in length)
    constructor Scanner.Scanner(Readable,Pattern) is not applicable
      (actual and formal argument lists differ in length)
MathMenu.java:64: error: method menu in class MathMenu cannot be applied to give
n types;
menu();
^
  required: String[]
  found: no arguments
  reason: actual and formal argument lists differ in length
2 errors

c:\java\bin>
4

3 回答 3

1

您的所有函数都获取名为a & b 的参数，但可以使用n & m。改变其中之一。例如：

private static int sum(int n, int m)
{
    return n+m;
}
于 2012-09-17T15:04:41.217 回答
1

您没有input在程序中定义，而是调用

选择=输入.nextInt();

假设你想从用户那里得到输入，你需要有

Scanner input = new Scanner(System.in)

就在之前choice=input.nextInt();

于 2012-09-17T15:04:49.097 回答
1

你从来没有input在方法体中定义你的变量menu。尝试Scanner input = new Scanner(System.in)在menu方法中添加。简单地定义变量 inmain并不能menu访问它。如果您想避免Scanner多次创建实例，您可以执行类似的操作

import java.util.Scanner;

public class MathMenu {
    private static Scanner input = new Scanner(System.in);
    ...
}

然后你可以使用你input所有的方法。

编辑：我刚刚注意到与和类似的东西m：n您必须在使用它们的方法中定义它们，或者使它们成为static字段。如果由我决定，我会这样做：

import java.util.Scanner;

public class MathMenu {
    private static Scanner input = new Scanner(System.in);
    private static int n = 15;
    private static int m = 8;

    // ...
    // your other methods unchanged
    // ...

    public static void main(String[] args) {
        menu(args);  // or just "menu()" if you remove the arguments from the menu method declaration.
    }
}
于 2012-09-17T15:06:32.520 回答