用java解leetcode上easy题5

public class Solution {
public String reverseString(String s) {
return new StringBuilder(s).reverse().toString();
}
}

import java.util.Collections;//java.lang包是自动导入的，不需要手动
import java.util.Arrays;
public class Solution {
public String reverseString(String s) {
char[] str = s.toCharArray();
Character[] str2 = new Character[str.length];
for(int i =0;i<str.length;i++){
str2[i] = str[i];
}
Collections.reverse(Arrays.asList(str2));
StringBuffer buff = new StringBuffer();
for(int j =0; j<str2.length; j++){
buff.append(str2[j]);
}
return buff.toString();
}
}