How to use the Split function in Java

How to use the Split function in Java

There are also String.Split () methods in the Java.lang package, similar to. NET, where returns are a character array, but there are a few tricks to use.
If executed: "2|33|4". Split ("|")

The result is:

""

2

|

3

3

|

4

Strange, but take a look at the API instructions or know why.

Java.lang.string.split
Split method
Splits a string into a substring and returns the result as an array of strings.
Stringobj.split ([Separator,[limit]])
Parameters
Stringobj
Required option. The String object or text to be exploded. The object is not modified by the split method.
Separator
Options available. A string or regular expression object that identifies whether one or more characters are used to delimit a string. If this option is omitted, an array of single elements containing the entire string is returned.
Limit
Options available. This value is used to limit the number of elements returned in an array.

Description
The result of the split method is an array of strings, where each occurrence of separator in the stingobj is decomposed

So the normal way to do this is:

1. If you use "." As a separate word, it must be written as follows: String.Split ("\"), so that the correct separation can be separated, can not use String.Split (".");
2. If you use "|" As a separate word, must be written as follows: String.Split ("\\|"), so that the correct separation, can not use String.Split ("|");
“.” and "|" All are escape characters, must add "\";
3. If you have more than one separator in a string, you can use the "|" As hyphens, such as "a=1 and b =2 or c=3", separate all three, and use String.Split ("And|or");

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Ava String.Split () Summary of Usage

There is a String.Split () method in the Java.lang package, which returns an array

I use some in the application, for you to sum up, for your reference only:

1. If you use "." As a separate word, it must be written as follows, String.Split ("\"), so that the correct separation can be separated from the String.Split (".");

2. If you use "|" As separate words, must be written as follows, String.Split ("\\|"), so that the correct separation, can not use String.Split ("|");

“.” and "|" All are escape characters, must add "\";

3. If you have more than one separator in a string, you can use the "|" As a hyphen, like, "Acount=?" and UU =? Or n=? ", the three are separated, you can use String.Split (" And|or ");

When you use the String.Split method to separate strings, the delimiter may not get the results we expected if it uses some special characters.

Let's see JDK doc for a description.

Public string[] Split (String regex)

Splits this string around matches of the given regular expression.

The argument regex is a regular-expression match pattern rather than a simple string, and he may have unexpected results for some special characters, such as testing the following code with a vertical bar | Separate strings, you will not get the expected results

   string[] aa = "AAA|BBB|CCC". Split ("|");

    string[] aa = "AAA|BBB|CCC". Split ("\\|"); This will get the correct result for

    (int i = 0; I <aa.length i++) {

      System.out.println ("--" +aa[i]); 

    

Running with the vertical * separator string will throw the java.util.regex.PatternSyntaxException exception, with the plus sign +.

    string[] aa = "AAA*BBB*CCC". Split ("*");

    string[] aa = "AAA|BBB|CCC". Split ("\\*"); This will get the correct result for    

    (int i = 0; I <aa.length i++) {

      System.out.println ("--" +aa[i]); 

    }  

Obviously, + * is not a valid pattern-matching rule expression, it can be escaped with "\\*" "\\+" to get the correct result.

The "|" divider string, while being able to execute, is not intended, "\\|" The correct result can be obtained after escaping.

Also, if you want to use the "\" character in a string, you also need to escape. The first way to express "AAAA\BBBB" is to use the string "AAAA\\BBBB", if you want to separate it should be so that you can get the correct result,

string[] aa = "AAA\\BBB\\BCCC". Split ("\\\\");