Java Split function error

Execute the following code

public class App {    public static void main(String[] args) {        String str = "123+456+712";        String[] strings = str.split("+");        System.out.println(Arrays.toString(strings));    }}

Throw exception

Exception in thread "main" java.util.regex.PatternSyntaxException:Dangling Meta character ' + ' near index 0

• ^
  At Java.util.regex.Pattern.error (Unknown Source)
  At Java.util.regex.Pattern.sequence (Unknown Source)
  At java.util.regex.Pattern.expr (Unknown Source)
  At Java.util.regex.Pattern.compile (Unknown Source)
  At Java.util.regex.Pattern.

This occurs because the String class's Split method split accepts a parameter that is a regular expression, which is a meta- + character of the regular expression, which needs to be escaped or throws an exception. Stringthe methods of the class are split as follows.

public String[] split(String regex) {    return split(regex, 0);}

The escape in Java's regular is used \\ , so modify it. \\+ + converts from metacharacters to normal + characters.

public class App {    public static void main(String[] args) {        String str = "123+456+712";        String[] strings = str.split("\\+");        System.out.println(Arrays.toString(strings));    }}

Reference

It's so easy to read regular expressions.
Syntax and examples for Java regular expressions

Java Split function error