显示菜单编译错误

-1

我是新来的Java，请裸露在我身边。我只是困惑，为什么有一个编译错误，我应该如何解决它。另外，在最后一条if语句中，当用户输入一个有效的整数时，我应该再次重复该菜单。我应该怎么做？提前致谢。显示菜单编译错误

public class MainMenu { 
public static void main(String[] args) 
    { 
    System.out.println("My First Java program can do many things!"); 
    System.out.println("1.Estimate population\n2.Generate random integer\n3. Print ASCII  table\n4. Approximate pi by iteration"); 
    System.out.println("What would you like to do? (1-4)"); 
    System.out.print("Your choice: "); 
    int input = 0; 
    Scanner keyboard = new Scanner(System.in); 
    switch (keyboard.nextInt()) 
    { 
     case 1: 
      System.out.println("You chose to estimate population."); 
      break; 
     case 2: 
      System.out.println("You chose to generate random integer."); 
      break; 
     case 3: 
      System.out.println("You chose to print ASCII table."); 
      break; 
     case 4: 
      System.out.println("You chose to approximate pi by iteration."); 
      break; 
    } 

    if(input>4 || input<1) 
    { 
     System.out.println("Sorry, I don't know what to do. Please try again."); 
     keyboard.next(); 
     if(!keyboard.hasNextInt()) 
    { 
     System.out.println("Sorry, only integers allowed for this menu. Good-bye!"); 
     System.exit(0); 
    } 
    keyboard.next(); 
    input = keyboard.nextInt(); 
    keyboard.nextLine(); 
}

来源

2014-09-22 awxf218

马上就要指出，你有三个语句（以keyboard.next（）;开头）在MainMenu类之外。 – MarsAtomic 2014-09-22 22:44:28

标准输入复制标准输入是空编译信息 Main.java:35：错误：到达文件末尾，而解析 } ^ 1错误标准输出标准输出是空 – awxf218 2014-09-22 22:47:13

所以这三个语句移动到类。任何类定义中的最后一件事应该是一个正确的大括号。 – MarsAtomic 2014-09-22 22:48:11

您的代码需要很多更改才能使其工作，首先需要连续循环，它将持续运行并等待用户输入。然后，如果输入不是整数，则必须捕获InputMismathexeption，您必须在代码的开头执行该操作。提供代码是一个坏主意，它会停止尝试不同的方式。我仍然附上代码。

import java.util.InputMismatchException; 
import java.util.Scanner; 
public class Test { 
public static void main(String[] args) { 
    System.out.println("My First Java program can do many things!"); 
System.out.println("1.Estimate population\n2.Generate random integer\n3. Print ASCII  table\n4. Approximate pi by iteration"); 
    System.out.println("What would you like to do? (1-4)"); 
    System.out.print("Your choice: "); 

    Scanner keyboard = new Scanner(System.in); 
    while (true) { 
     int input = 0; 
     try { 
      input = keyboard.nextInt(); 
     } catch (InputMismatchException e) { 
      System.out 
        .println("Sorry, only integers allowed for this menu. Good-bye!"); 
      System.exit(0); 
     } 
     switch (input) { 
     case 1: 
      System.out.println("You chose to estimate population."); 
      break; 
     case 2: 
      System.out.println("You chose to generate random integer."); 
      break; 
     case 3: 
      System.out.println("You chose to print ASCII table."); 
      break; 
     case 4: 
      System.out.println("You chose to approximate pi by iteration."); 
      break; 
     } 

     if (input > 4 || input < 1) { 
      System.out 
        .println("Sorry, I don't know what to do. Please try again."); 
     } 
    } 
} 
}

来源

2014-09-23 00:17:10

显示菜单编译错误

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