java遍历字符串打印每一个字符

		String str = "james";

 		 //方法一
        char[] charArray = str.toCharArray();
        for (char i:charArray){
            System.out.println(i);
        }
        

        // 方法二
        for (int i = 0; i < str.length(); i++) {
            System.out.println(str.charAt(i));
        }

        //方法三
        for (int i = 0; i < str.length(); i++) {
            System.out.println(str.substring(i, i + 1));
        }

将字符串james dog keith反着输出，输出结果是keith dog james

 String str = "james dog keith";

 String[] strArr = str.split(" "); //将字符串根据空格分割形成一个新的数组
 StringBuilder stringBuilder = new StringBuilder("");
        for (int i = strArr.length-1;i >= 0;i--){//倒叙遍历数组
            stringBuilder.append(strArr[i]).append(" ");
        }
        System.out.println(stringBuilder);