题解 | #java反转字符串#

/**
 * 反转字符串 遍历整个字符数组
 * @param str string字符串
 * @return string字符串
 */
public String solve1(String str) {
    String temp = "";
    int length = str.length();
    for(int i = length - 1; i >= 0; --i) {
        temp+=str.charAt(i);
    }
    return temp;
}

/**
 * 同上,字符串+=替换成StringBuilder 的append方法
 */
public String solve2(String str) {
    char[] chars = str.toCharArray();
    int size = chars.length;
    StringBuilder tem = new StringBuilder();
    int length = str.length();
    for(int i = length - 1; i >= 0; --i) {
        tem.append(str.charAt(i));
    }
    return tem.toString();
}

/**
 * 同上
 */
public String solve3(String str) {
    char[] chars = str.toCharArray();
    int size = chars.length;
    StringBuilder tem = new StringBuilder();
    for (int i = size - 1; i >= 0; --i) {
        tem.append(chars[i]);
    }
    return tem.toString();
}

/**
 * JDK StringBuilder 的reverse()方法
 */
public String solve4(String str) {
    return new StringBuilder(str).reverse().toString();
}

/**
 *
 */
public String solve5(String str) {
    char[] array = str.toCharArray();
    Stack<Character> stack = new Stack<>();
    int length = array.length;
    for (int i = 0; i < length; i++) {
        stack.push(array[i]);
    }

    array = new char[length];

    for (int i = 0; i < length; i++) {
        array[i] = stack.pop();
    }

    return String.valueOf(array);
}

/**
 * 字符数组首尾替换,只需要遍历一半就可以
 */
public String solve(String str) {
    char[] array = str.toCharArray();
    int length = array.length;
    int index = length / 2;
    char temp;
    for (int i = 0, j = length - 1; i < index; ++i,--j) {
        temp = array[i];
        array[i] = array[j];
        array[j] = temp;
    }
    return String.copyValueOf(array);
}

/**
 * 字符数组首尾替换,只需要遍历一半就可以
 */
public String solve7(String str) {
    int length = str.length();
    int index = length / 2;
    char[] array = new char[length];
    for (int i = 0, j = length - 1; i <= index; ++i,--j) {
        if (i == j) {
            array[i] = str.charAt(j);
            break;
        }
        array[i] = str.charAt(j);
        array[j] = str.charAt(i);
    }
    return String.copyValueOf(array);
}