In Java, how do I parse multiple values of a single field to a String array?

Question

I have a line of plaintext that contains a series of tags delimited by a plus sign:

event name @location +tag1 +tag2 +tag3 +tag4

The data fields alway sappear in the same order: Name, Location, Tags. There is always ONLY ONE instance of name and location, but there can be one or more tags. I'd like to be able to replicate the .NET StringSplit method (write all delimited strings to an array) in Java, but can't seem to wrap my head around doing it.

My desired output for the tag field from the above example would be:

tag[0] = tag1
tag[1] = tag2
tag[2] = tag3
tag[3] = tag4

First, the closest method I can find would be split which uses regex. But I'm not sure how I would code the regex to EXCLUDE from the array any characters that are before the first +.

I thought of getting a count of + in a particular row and using a for loop to parse and create tagString[count-of-plusses], but would that step through multiple instances of +nnnnn on a single line?

Any suggestions on a good way to approach this?

Jon Taylor · Accepted Answer · 2012-07-13 15:35:56Z

2

If you look at the javadoc for String specifically:

public String[] split(String regex)

This will allow you to split a string around whatever you like and return an array of strings.

You can use the version of this method with the limit parameter too. Use this first to allow you to get rid of all the stuff before then do it again without the limit parameter.

answered Jul 13, 2012 at 15:35

Jon Taylor

7,9255 gold badges32 silver badges55 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

assylias · Accepted Answer · 2012-07-13 15:37:37Z

2

You can split the string and copy the returned array without the first item:

String s ="event name @location +tag1 +tag2 +tag3 +
String[] items = s.split("\\+");

//remove the `event name  @location` part
String[] tags = new String[items.length - 1];
System.arraycopy(items, 1, tags, 0, items.length - 1);

Make sure you add relevant sanity checks (on length of items being > 1 for example).

answered Jul 13, 2012 at 15:37

assylias

330k84 gold badges680 silver badges806 bronze badges

Comments

Alan Hay · Accepted Answer · 2012-07-13 15:35:37Z

0

Use the String methods indexOf() and subString() to get the relevant part of the String i.e. discard everything before the first +.

Then work on this Substring using split() with + as the delimiter and trim() to discard whitespace.

answered Jul 13, 2012 at 15:35

Alan Hay

23.3k4 gold badges64 silver badges119 bronze badges

Comments

Arvik · Accepted Answer · 2012-07-13 15:39:19Z

0

If you don't want to use regex then try http://docs.oracle.com/javase/1.4.2/docs/api/java/util/StringTokenizer.html.

answered Jul 13, 2012 at 15:39

Arvik

2,6342 gold badges17 silver badges10 bronze badges

Comments

Simulant · Accepted Answer · 2012-07-13 15:40:16Z

0

to get rid of the chars before the first + just ignore the first item in the array.

    String input = "+tag1+tag2+tag3+tag4";
    String[] splitted = input.split("\\+");     
    System.out.println(Arrays.toString(splitted));
    //returns [, tag1, tag2, tag3, tag4]

    input = "xxx+tag1+tag2+tag3+tag4";
    splitted = input.split("\\+");      
    System.out.println(Arrays.toString(splitted));
    //returns [xxx, tag1, tag2, tag3, tag4]

answered Jul 13, 2012 at 15:40

Simulant

20.2k10 gold badges68 silver badges106 bronze badges

Comments

ioreskovic · Accepted Answer · 2012-07-13 15:43:29Z

0

input.split(" +")[1]     // you have "tag1 +tag2 +tag3 +tag4" now
     .split("\\s+\\+");  // you have {tag1, tag2, tag3, tag4} now

answered Jul 13, 2012 at 15:43

ioreskovic

5,7377 gold badges41 silver badges71 bronze badges

1 Comment

assylias Over a year ago

It is difficult to add a check with that syntax (i.e. you will get an IndexOutOfBoundsException if there is no " +" in the original string).

Pang · Accepted Answer · 2018-10-18 01:50:26Z

0

Try this.

String string = "event name @location +tag1 +tag2 +tag3 +tag4";                        
String[] ss = string.split(" ");
String[] tag = new String[ss.length - 3];
for (int i = 3 ; i < ss.length; i++) {
    tag[i-3] = ss[i].replace("+", "");
}

edited Oct 18, 2018 at 1:50

Pang

10.2k146 gold badges87 silver badges126 bronze badges

answered Jul 14, 2012 at 11:39

Isuru

8,2438 gold badges33 silver badges39 bronze badges

Collectives™ on Stack Overflow

In Java, how do I parse multiple values of a single field to a String array?

7 Answers 7

Comments

Comments

Comments

Comments

Comments

1 Comment

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

7 Answers 7

Comments

Comments

Comments

Comments

Comments

1 Comment

Comments

Your Answer

Sign up or log in

Post as a guest

Related