java基础将字符串进行反转

将字符串进行反转

方法一： 

//定义String 
    String text = "abcdefr";
    //反转后的String 
    String newText = "";
    //循环取出每一个字符
    for (int i = 0; i < text.length(); i++) {
      //倒序拼接
      newText = text.charAt(i)+newText;
    }
    
    System.out.println(newText);

这种方法来说是有点效率上的问题上的，具体分析请查看 

String 的详细分析

方法二 

//定义String 
        String text = "abcdefr";
        //创建 StringBuilder
        StringBuilder stringBuilder = new StringBuilder();
        //循环遍历取出
        for (int i = text.length()-1; i >=0; i--) {
          //倒序取出 拼接
          stringBuilder.append(text.charAt(i));
        }
        //转成新的 String 
        String string = stringBuilder.toString();
        
        System.out.println(string);

方法三 

//定义String 
    String text = "abcdefr";
    StringBuilder stringBuilder = new StringBuilder(text);
    //反转
    stringBuilder.reverse();
    //反转后的 String 
    String newString = stringBuilder.toString();
    
    System.out.println(newString);

方法四 

//定义String 
    String text = "abcdefr";
    //将String 转字符数组
    char[] textChars = text.toCharArray();
    int n = textChars.length - 1;
    int halfLength = n / 2;
    //循环将 字符数组中的字符反转 
    for (int i = 0; i <= halfLength; i++) {
      //反转替换
      char temp = textChars[i];
      textChars[i] = textChars[n - i];
      textChars[n - i] = temp;
    }

    //构造反转后的 String 
    String newString = new String(textChars);

    System.out.println(newString);

方法五 

//定义String 
    String text = "abcdefr";
    //转字符数组
    char[] str = text.toCharArray();
    //创建 Stack 
    Stack<Character> stack = new Stack<Character>();
    //将字符保存到Stack中
    for (int i = 0; i < str.length; i++){
      stack.push(str[i]);
    }

    //定义 SingBuilder
    StringBuilder stringBuilder = new StringBuilder();

    //将Stack中的字符取出 添加到StringBuilder中
    for (int i = 0; i < str.length; i++){
      stringBuilder.append(stack.pop());
    }
    //反转后的 String 
    String rverseString = stringBuilder.toString();

    System.out.println(rverseString);