trimメソッド

//Sample_trim.java
class Sample_trim{
    public static void main(String[] args){
      String str1 = " 半角 空白 ";
      String str2 = "\tタブ\tタブ\t";
      String str3 = "　全角　空白　";

      str1 = str1.trim();
      str2 = str2.trim();
      str3 = str3.trim();

      System.out.println("str1 = [" + str1 + "]");
      System.out.println("str2 = [" + str2 + "]");
      System.out.println("str3 = [" + str3 + "]");
    }
}

>cd ws
ws>javac -encoding UTF-8 Sample_trim.java
ws>java Sample_trim
str1 = [半角 空白]
str2 = [タブ    タブ]
str3 = [　全角　空白　]     <---- 全角空白は除かれません。