顯示菜單編譯錯誤

-1

我是新來的Java，請裸露在我身邊。我只是困惑，爲什麼有一個編譯錯誤，我應該如何解決它。另外，在最後一條if語句中，當用戶輸入一個有效的整數時，我應該再次重複該菜單。我應該怎麼做？提前致謝。顯示菜單編譯錯誤

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(); 
}

來源

2014-09-22 awxf218

馬上就要指出，你有三個語句（以keyboard.next（）;開頭）在MainMenu類之外。 – MarsAtomic 2014-09-22 22:44:28

標準輸入複製標準輸入是空編譯信息 Main.java:35：錯誤：到達文件末尾，而解析 } ^ 1錯誤標準輸出標準輸出是空 – awxf218 2014-09-22 22:47:13

所以這三個語句移動到類。任何類定義中的最後一件事應該是一個正確的大括號。 – MarsAtomic 2014-09-22 22:48:11

您的代碼需要很多更改才能使其工作，首先需要連續循環，它將持續運行並等待用戶輸入。然後，如果輸入不是整數，則必須捕獲InputMismathexeption，您必須在代碼的開頭執行該操作。提供代碼是一個壞主意，它會停止嘗試不同的方式。我仍然附上代碼。

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."); 
     } 
    } 
} 
}

來源

2014-09-23 00:17:10

顯示菜單編譯錯誤

回答

相關問題