Java正则表达式不起作用-字符串拆分

Question

I have a string variable and want to extract a value from it.

String LB0001 = "LB0001"; 
String[] splitString = LB0001.split("LB(.*)"); 

What I was expecting is that splitString would contain two values, ["LB0001",["0001"]] . However the result is null. Why? I have checked the regex and seems to be correct.

I want to extract "0001". I can do it using other ways, but would like to know what I am doing wrong here.

Answer 1

The split method will split where ever the regular expression provided matches. In your case, the expression LB(.*) matches the provided string completely, thus you get nothing back.

If you want to get the number part, you can split on anything which is not a digit, like so: .split("\\\\D") . This should get you 1 element which contains 0001 .

EDIT: If you want anything after LB you would need to use the Pattern and Matcher class. So basically something like so:

String str = "LB0001";
Pattern p = Pattern.compile("LB(.*?)");
Matcher m = p.matcher(str);
while(m.find())
    System.out.println(m.groups(1));

The above will make use of regular expressions to look for any text which follows LB . I have changed it from .* to .*? in case you have something like so: LB001LB333 . The extra ? makes the expression non greedy.

Answer 2

try this

String LB0001 = "LB0001"; 
String[] splitStringAlpha = LB0001.split("[a-zA-Z]+");
System.out.println(splitStringAlpha[0]); 
String[] splitStringNum = LB0001.split("\\D");
System.out.println(splitStringNum[0]);

this should give you

LB
0001