JAVA中如何去除字符串前后的全角空格(当中保留)(轉)

public static void main(String[] args) {
    String a = "   aaaa aaaa   ";
    a = a.trim();
    while(a.startsWith(" ")){
       a = a.substring(1,a.length()).trim();
    }
    while(a.endsWith(" ")){
       a = a.substring(0,a.length()-1).trim();
    }
    System.out.println(a);
  }