如果这是一个怪异的问题，我感到很抱歉，但是我刚刚开始OOP，并遇到了一个我应该制作的简单菜单驱动数学程序。我清除了编译器给我的所有错误，但是现在它给了我大约14个新错误，其中大多数被描述为“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

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>