Java -- String. split () function, javastring. split
In java doc, there are String [] java. lang. String. split (String regex)
Splits this string around matches of the given regular expression.
This method works as if by invoking the two-argumentsplit
Method with the given expression and a limit argument of zero. Trailing empty strings are therefore not supported ded in the resulting array.
The string"Boo: and: foo", For example, yields the following results with these expressions:
Regex |
Result |
: |
{ "boo", "and", "foo" } |
o |
{ "b", "", ":and:f" } |
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Parameters:
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RegexThe delimiting regular expression
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Returns:
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The array of strings computed by splitting this string around matches of the given regular expression
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Throws:
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PatternSyntaxException-if the regular expression's syntax is invalid
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Since:
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1.4
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See Also:
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Java. util. regex. Pattern
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@ Spec
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JSR-51
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Note the following:
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(1) If "." is used as the separator, String. split ("\.") must be written as follows.
String. split (".");
For example, this Code:
String str="123.456";String []arrStr=str.split(".");System.out.println(arrStr.length);
Result:
String str = "123.456"; String [] arrStr = str. split ("\."); System. out. println (arrStr. length );
Result:
The reason is:
Splits this string around matches of the given regular expression. It requires a regular expression, so it must meet the regular expression form,
Therefore, escape is required.
The source code of the split () function is provided below for your reference:
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); }
Public String [] split (String regex ){
Return split (regex, 0 );
}
What is the use of the split function of the String class in java? Are the first and last elements of the array output after I split the string empty?
It is useless. Just a few lines of code that you can run on your own.
String aa = "a, B, c, d, e, f ";
String [] bb = aa. split (",");
For (int I = 0; I <bb. length; I ++ ){
System. out. println (bb [I]);
}
Java code: Use of split
The parameter of the split function is not a string but a regular expression.
+ The number itself is a special character in a regular expression and needs to be escaped.
String [] array = str. split ("\\+ ");