java大小写转换反转

import java.io.*;
public class Main {
	
	public static void main(String args[]){
		
		BufferedReader bufReader = new BufferedReader(new InputStreamReader(System.in));		
				
		String strBuf;
		
		try {
			while ((strBuf = bufReader.readLine()) != null){
				
				System.out.println(cover(strBuf));
							
			}
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}		
	}
	
	public static String cover(String str){
		
		int len = str.length();
		char[] chs = new char[len];
		int j=0;
		
		for(int i=len-1;i>=0;i--){
			if(str.charAt(i) != ‘ ‘){
				chs[j] = str.charAt(i);
				if(chs[j]>=‘a‘&&chs[j]<=‘z‘)
					chs[j]-=32;
				else if(chs[j]>=‘A‘&&chs[j]<=‘Z‘)
					chs[j]+=32;
				j++;
			}
		}
		return String.valueOf(chs);
	}
}