字符串反转的几种方法

 

public class ReverseTest {
    public static void main(String[] args) {
        String result = ReverseByStack("12345");
        System.out.println(result);
    }

    //直接使用字符串拼接
    public static String ReverseByString(String str) {
        String result = "";
        for (int i = str.length() -1; i >= 0 ; i--) {
            result += str.charAt(i);
        }
        return result;
    }
 
    //使用Stringbuffer
    public static String reverseByStringbuffer(String str) {
        char[] charArray = str.toCharArray();
        StringBuffer temp = new StringBuffer();
        for (int i = charArray.length; i > 0; i--) {
            temp.append(charArray[i - 1]);
        }
        
        //StringBuffer result = new StringBuffer(str);  //直接使用StrngBuffer的逆转方法
        //result.reverse();
        return temp.toString();
    }
 
    //使用字符数组
    public static String ReverseByCharArray(String str) {
        char[] charArray = str.toCharArray();
        int length = charArray.length;

        char[] resultCharArray = new char[length];

        for (int i = 0; i < length; i++) {
            resultCharArray[length - 1 - i] = charArray[i];
        }
        return new String(resultCharArray);

    }

    //使用字符数组<优化版> 对于上面的遍历，其实只需要遍历一半即可
    public static String ReverseByCharArray2(String str) {
        char[] charArray = str.toCharArray();
        int length = charArray.length;

        char[] resultCharArray = new char[length];

        for (int i = 0; i <= length / 2; i++) {
            resultCharArray[length - 1 - i] = charArray[i];
            resultCharArray[i] = charArray[length - 1 - i];
        }
        return new String(resultCharArray);

    }

    //使用堆栈，栈是一个很神奇的数据结构。我们可以使用它后进先出的特性来对数组进行反转。先将数组所有元素压入栈，然后再取出，顺序很自然地就与原先相反了。
    public static String ReverseByStack(String str) {
        char[] charArray = str.toCharArray();
        int length = charArray.length;
        
        char[] result = new char[length];
        Stack<String> stack = new Stack<String>();
        for (int i = 0; i < length; i++) {  //压入栈中
            stack.push(String.valueOf(charArray[i]));
        }
        
        for (int i = 0; i < length; i++) {  //出堆
            result[i] = stack.pop().charAt(0);
        }
        return new String(result);
    }
}