String 연습문제

public class StringEx {
	public static String midStr(String s) {
		
	}
	
	public static String reverseString(String s) {
		
	}
	public static String convertString(String s) {
		 
	}
	public static void main(String[] args) {
		System.out.println(StringEx.midStr("abcd"));  //bc
		System.out.println(StringEx.midStr("abcde")); //c 
		System.out.println(StringEx.reverseString("abcdef"));  //fedcba
		System.out.println(StringEx.convertString("aBcd")); //AbCD 

	}

}