java中的简单For循环

 public void reverseString(char[] s) {
    int length = s.length;
    for (int i = 0; i < s.length / 2; i++) {
        // swaping character
        char temp = s[length - i - 1];
        s[length - i - 1] = s[i];
        s[i] = temp;
    }
}

        String str = "Hello World";

        char[] strCharArr = str.toCharArray();

        for(int i = 0, k= strCharArr.length-1;i != k; i++, k--) {
            char temp = strCharArr[i];
            strCharArr[i] = strCharArr[k];
            strCharArr[k] = temp;
        }

        System.out.println(String.valueOf(strCharArr));

public static String revString(String str){
    char[] revCharArr = str.toCharArray();
    for (int i=0; i< str.length()/2; i++){
        char f = revCharArr[i];
        char l = revCharArr[str.length()-i-1];
        revCharArr[i] = l;
        revCharArr[str.length()-i-1] = f;
    }
    String revStr = new String(revCharArr);
    return revStr;
}

它会得到你输入的值，并反向返回;)

public static  String reverse (String a){
    char[] rarray = a.toCharArray();
    String finalvalue = "";
    for (int i = 0; i < rarray.length; i++)
    {
        finalvalue += rarray[rarray.length - 1 - i];
    }   
return finalvalue;

}

public static String reverseIt(String source) {
    int i, len = source.length();
    StringBuilder dest = new StringBuilder(len);

    for (i = (len - 1); i >= 0; i--){
        dest.append(source.charAt(i));
    }

    return dest.toString();
}

http://www.java2s.com/Code/Java/Language-Basics/ReverseStringTest.htm

你可以用这个:

new StringBuilder(hi).reverse().toString()

StringBuilder是在Java 5中添加的。对于Java 5之前的版本，可以使用StringBuffer类-它具有相同的API。