这是一个将字符串按照指定的delimiters（分隔符）进行分割的类。
首先看看他的构造函数：
public StringTokenizer(String str, String delim, boolean returnDelims) {
currentPosition = ;
newPosition = -;
delimsChanged = false;
this.str = str;
maxPosition = str.length();
delimiters = delim;
retDelims = returnDelims;
setMaxDelimCodePoint();
}
public StringTokenizer(String str, String delim) {
this(str, delim, false);
}
默认是不返回delimiters的。
public StringTokenizer(String str) { this(str, " \t\n\r\f", false); }
这个是个默认的构造函数，其中使用的默认的delimiter是 " \t\n\r\f"
2、遍历边界
public boolean hasMoreTokens() {
/*
* Temporarily store this position and use it in the following
* nextToken() method only if the delimiters haven't been changed in
* that nextToken() invocation.
*/
newPosition = skipDelimiters(currentPosition);
return (newPosition < maxPosition);
}
查看是不是还有其他的分割串，这个通常作为遍历这个字符串是否结束的判断条件
3、获取每一个分割串
public String nextToken() {
/*
* If next position already computed in hasMoreElements() and
* delimiters have changed between the computation and this invocation,
* then use the computed value.
*/
currentPosition = (newPosition >= && !delimsChanged) ?
newPosition : skipDelimiters(currentPosition);
/* Reset these anyway */
delimsChanged = false;
newPosition = -;
if (currentPosition >= maxPosition)
throw new NoSuchElementException();
int start = currentPosition;
currentPosition = scanToken(currentPosition);
return str.substring(start, currentPosition);
}
上面最后一句代码可以看出，使用的是字符串的一些操作，就是返回相应的字串。
这里还有一个特殊的方法，返回指定delimiter分割串
public String nextToken(String delim) {
delimiters = delim;
/* delimiter string specified, so set the appropriate flag. */
delimsChanged = true;
setMaxDelimCodePoint();
return nextToken();
}
4、查看该字串串被分为了多少个字串
public int countTokens() {
int count = ;
int currpos = currentPosition;
while (currpos < maxPosition) {
currpos = skipDelimiters(currpos);
if (currpos >= maxPosition)
break;
currpos = scanToken(currpos);
count++;
}
return count;
}
此时，如果没有指定delimiter的话，将会返回0