如何告诉Java在字符串中的某个字符处停止循环？

Question

So if i have a method where a string is entered and has a hyphen. like "cool*boy" if i want java to make a new string that starts out at the end of that string and prints each letter backward and continues until it reaches the asterisk and then goes forward and prints all the letters after the asterisk again so in the cool*boy example it's "yobboy" or high*school would be "loohcsschool" ... how would I do this. Thank you.

to JUST get everything up to the asterisk sign (which isn't working) I put,

int i;
String newStr = "";
for(i=s.length()-1; i >= s.charAt('*'); i--)
     newStr = newStr + s.charAt(i);

I'm guessing you're not allowed to make that condition in the for loop. But I just don't get how you would do it. Please help thanks!

Answer 1

将条件更改为

s.charAt(i) != '*'

Answer 2

The simplest way to do this would be to use a substring instead of a loop.

String forward = s.substring(s.indexOf('*')+1);
String reverse = new StringBuilder(forward).reverse().toString();
return reverse+forward;

Answer 3

not tested codes:

String s = "high*school";

    String newString = "";
    String[] arr = s.split("[*]");
    if (arr.length == 2) {
        newString = new StringBuilder(arr[1]).reverse().toString() + arr[1];
    }else{
       ... if the string has no (or more than one) "*"...
        handle it if it is reqired.
     }

Answer 4

Don't reinvent the wheel. Apache Commons StringUtils library:

substringBefore(String str, String separator)

substringAfter(String str,  String separator)

reverse(String str)

Link: http://commons.apache.org/proper/commons-lang/javadocs/api-3.3.2/index.html