Switch Statement請幫我查看

Question

我對這個有點新，但是？任何人都可以糾正我的第一個switch語句我不知道該用什麼表情來啓動的情況下：

和IM甚至不知道，如果起始聲明甚至正確

import java.io.*; 
    public class SwitchDemo { 
    public static void main(String[] args) { 


    BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); 
    String input= br.readLine(); 

    System.out.println("Press Enter"); 
    System.out.println("a.Hello: Asks the name of the user."); 
    System.out.println("b.Array: Input elements and search for a specified key and prints a  message."); 
    System.out.println("c.MagicSquare: Displays [7][7] magic square."); 
    System.out.println("d.Bubble Sort: Alphabetically sorts 20 employees using bubble sort."); 
    System.out.println("e.Selection Sort: Alphabetically sorts 20 employees using selection sort"); 
    System.out.println("f.Insertion Sort: Alphabetically sorts 20 employees using Insertion sort"); 
    System.out.println("g.Factorial: Run the Factorial application"); 
    System.out.println("h.Triangle: Run the Triangle application."); 
    System.out.println("i.MergeSort: Performs the mergesort of a two class databasse."); 
    System.out.println("j.Stack_1: Perform reversal of string."); 
    System.out.println("k.Stack_2: Perform Infix Notation"); 
    System.out.println("l.Postfix: Perform Postfix Notation"); 
    System.out.println("m.Linked List"); 
    System.out.println("n.Queue:"); 
    System.out.println("o.Exit:"); 

     switch (input) { 
      case a: 

      String usersName;  
      String upperCaseName; 

      TextIO.put("Please enter your name: "); 
      usersName = TextIO.getln(); 

      upperCaseName = usersName.toUpperCase(); 

      TextIO.putln("Hello, " + upperCaseName + ", nice to meet you!"); 


        break; 
      case b: 
     // Code for b execution here. Run array. 
        break; 
      case c: 
     // Code for c execution here. magicsquare. 
        break; 
      case d: 
     // Code for d execution here. Bubble sort. 
        break; 
      case e: 
     // Code for e execution here. selection sort. 
        break; 
      case f: 
     // Code for f execution here. insertion sort. 
        break; 
      case g: 
     // Code for g execution here. recursion. 
        break; 
      case h: 
     // Code for h execution here. mergesort. 
        break; 
      case i: 
     // Code for b execution here. stack1. 
        break; 
      case j: 
     // Code for b execution here. stack2. 
        break; 
      case k: 
     // Code for b execution here. link list. 
        break; 
      default: 
     System.out.println("Please input selection from a-o"); 
        break; 
     } 

    } 
} 

Answer 1

正如其他人所說，使用

switch(input) { 
    case "a": 
     // do stuff 
     break; 
    case "b": 
     // do more stuff 
     break; 
} 

會工作。 又一個的事情，如果你是在Java 7（Java的版本）的工作，你應該能夠擺脫

BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); 

與

Scanner in = new Scanner(System.in); 
String input = in.nextLine(); 

至少對我來說是更換很容易使用。剛剛進口

import java.util.Scanner; 

Answer 2

你沒有檢查的情況下爲字符串（聲明輸入作爲一個字符串）。您正在調用名爲a,b等變量。請嘗試將它們放入引號中，如case: "a"中所示。

Answer 3

幾個百分點這裏

case語句都是這樣的（預1.7）

char input = 'a'; 

switch (input) { 
case 'a': 
    break; 
default : 
    System.out.println("default"); 

} 

爲Java 1.7及以後你也可以打開字符串

String input = "a"; 

switch (input) { 
case "a": 
    printHelloUser(); 
    break; 
default : 
    System.out.println("default"); 

} 

void printHelloUser() { 
     String usersName;  
     String upperCaseName; 

     TextIO.put("Please enter your name: "); 
     usersName = TextIO.getln(); 

     upperCaseName = usersName.toUpperCase(); 

     TextIO.putln("Hello, " + upperCaseName + ", nice to meet you!"); 


} 

您可能還在閱讀她的輸入之前要先考慮用戶prompting。