java 字符串 split() 方法根据给定的正则表达式拆分此字符串并返回一个字符数组。
内部实现
public String[] split(String regex, int limit) {
/* fastpath if the regex is a
(1)one-char String and this character is not one of the
RegEx's meta characters ".$|()[{^?*+\\", or
(2)two-char String and the first char is the backslash and
the second is not the ascii digit or ascii letter.
*/
char ch = 0;
if (((regex.value.length == 1 &&
".$|()[{^?*+\\".indexOf(ch = regex.charAt(0)) == -1) ||
(regex.length() == 2 &&
regex.charAt(0) == '\\' &&
(((ch = regex.charAt(1))-'0')|('9'-ch)) < 0 &&
((ch-'a')|('z'-ch)) < 0 &&
((ch-'A')|('Z'-ch)) < 0)) &&
(ch < Character.MIN_HIGH_SURROGATE ||
ch > Character.MAX_LOW_SURROGATE))
{
int off = 0;
int next = 0;
boolean limited = limit > 0;
ArrayList<String> list = new ArrayList<>();
while ((next = indexOf(ch, off)) != -1) {
if (!limited || list.size() < limit - 1) {
list.add(substring(off, next));
off = next + 1;
} else { // last one
//assert (list.size() == limit - 1);
list.add(substring(off, value.length));
off = value.length;
break;
}
}
// If no match was found, return this
if (off == 0)
return new String[]{this};
// Add remaining segment
if (!limited || list.size() < limit)
list.add(substring(off, value.length));
// Construct result
int resultSize = list.size();
if (limit == 0)
while (resultSize > 0 && list.get(resultSize - 1).length() == 0)
resultSize--;
String[] result = new String[resultSize];
return list.subList(0, resultSize).toArray(result);
}
return Pattern.compile(regex).split(this, limit);
}
签名
java 字符串中有两个 split() 方法的签名。
public String split(String regex)
and,
public String split(String regex, int limit)
参数
regex:正则表达式应用于字符串。
limit:限制数组中的字符串数。如果为零,它将返回与正则表达式匹配的所有字符串。
返回
字符串数组
抛出
如果正则表达式的模式无效,则 PatternSyntaxException
自从
1.4
Java String split() 方法示例
给定的示例仅返回字符串中不包括空格的单词总数。它还包括特殊字符。
public class SplitExample{
public static void main(String args[]){
String s1="java string split method by javatpoint";
String[] words=s1.split("\\s");//splits the string based on whitespace
//using java foreach loop to print elements of string array
for(String w:words){
System.out.println(w);
}
}}
java string split method by javatpoint
带有正则表达式和长度示例的 Java String split() 方法
public class SplitExample2{
public static void main(String args[]){
String s1="welcome to split world";
System.out.println("returning words:");
for(String w:s1.split("\\s",0)){
System.out.println(w);
}
System.out.println("returning words:");
for(String w:s1.split("\\s",1)){
System.out.println(w);
}
System.out.println("returning words:");
for(String w:s1.split("\\s",2)){
System.out.println(w);
}
}}
returning words: welcome to split world returning words: welcome to split world returning words: welcome to split world
带有正则表达式和长度示例 2 的 Java String split() 方法
在这里,我们将拆分限制作为该函数的第二个参数传递。这限制了拆分字符串的数量。
public class SplitExample3 {
public static void main(String[] args) {
String str = "Javatpointtt";
System.out.println("Returning words:");
String[] arr = str.split("t", 0);
for (String w:arr) {
System.out.println(w);
}
System.out.println("Split array length:"+arr.length);
}
}
Returning words: Java poin Split array length:2
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