java大小寫轉換

 import java.io.*;

public class convertToPrintString
{     //輸入小寫轉大寫,輸入大寫轉小寫
      public static void main(String[] args) throws IOException
      {
           InputStreamReader reader = new InputStreamReader(System.in);  
           BufferedReader input = new BufferedReader(reader);  
           System.out.print("Please enter your word:");  
           String text =  input.readLine();  
           String s = convertString(text);   //text為輸入文字，S為轉換後的文字。
           System.out.println(s);
       }
     
      public static String convertString(String str)
          {
              String upStr = str.toUpperCase();  
              String lowStr = str.toLowerCase();  
              StringBuffer buf = new StringBuffer(str.length());  
              for(int i=0;i<str.length();i++)
              {  
                 if(str.charAt(i)==upStr.charAt(i))
                 {  
                     buf.append(lowStr.charAt(i));  
                 }
                else
                {
                    buf.append(upStr.charAt(i));  
                 }  
               }  
               return   buf.toString();  
            }

        
      
}