java.lang.String.trim()函数的使用

String java.lang.String.trim()

先来个例子：

public static void main(String arg[]){    String a = "  Hello World!  ";    String b = "Hello World!";    System.out.println("a--" + a + "--");    System.out.println("b--" + b + "--");    System.out.println(a.equals(b));    a = a.trim();//去除首尾字符    System.out.println("a--" + a + "--");    System.out.println(a.equals(b));}

运行结果：

简单解释：

java.lang.String.trim() 方法返回一个字符串副本，并忽略(去除)开头和结尾的空格.

官方解释

Returns a string whose value is this string, with any leading and trailing whitespace removed.

If this String object represents an empty character sequence, or the first and last characters of character sequence represented by this String object both have codes greater than ‘\u0020’ (the space character), then a reference to this String object is returned.

Otherwise, if there is no character with a code greater than ‘\u0020’ in the string, then a String object representing an empty string is returned.

Otherwise, let k be the index of the first character in the string whose code is greater than ‘\u0020’ , and let m be the index of the last character in the string whose code is greater than ‘\u0020’ . A String object is returned, representing the substring of this string that begins with the character at index k and ends with the character at index m -that is, the result of this.substring(k, m + 1) .

This method may be used to trim whitespace (as defined above) from the beginning and end of a string. Returns: A string whose value is this string, with any leading and trailing white space removed, or this string if it has no leading or trailing white space.