Java How to split a string

To split a string, uses String.split(regex). Review the following examples :

	String phone = "012-3456789";
	String[] output = phone.split("-");
	System.out.println(output[0]);
	System.out.println(output[1]);

Output

	012
	3456789

1. Split a Period / dot

The period / dot is a special character in regex, you have to escape it either with a double backlash \\. or uses the Pattern.quote method.

package com.mkyong.test
import java.util.regex.Pattern;
public class TestSplit {
	public static void main(String[] args) {
		String test = "abc.def.123";
		String[] output = test.split("\\.");
		//alternative
		//String[] output = test.split(Pattern.quote("."));
		System.out.println(output[0]);
		System.out.println(output[1]);
		System.out.println(output[2]);

Output

abc
def
123

Some common checking before split.

package com.mkyong.test
import java.util.regex.Pattern;
public class TestSplit {
	public static void main(String[] args) {
		String test = "abc.def.123";
		if(test.contains(".")){
			String[] output = test.split("\\.");
			if(output.length!=3){
				throw new IllegalArgumentException(test + " - invalid format!");
			}else{
				System.out.println(output[0]);
				System.out.println(output[1]);
				System.out.println(output[2]);
		}else{
			throw new IllegalArgumentException(test + " - invalid format!");

2. StringTokenizer example

In the old days, Java developers like to use the StringTokenizer class to split a string. This is because the StringTokenizer class is available since JDK 1.0 and the String.split() is available since JDK 1.4

package com.mkyong.test
import java.util.StringTokenizer;
public class TestSplit {
	public static void main(String[] args) {
		String test = "abc.def.123";
		StringTokenizer token = new StringTokenizer(test, ".");
		while (token.hasMoreTokens()) {
			System.out.println(token.nextToken());

Output

abc
def
123

References

1. Java doc String.split
2. Java StringTokenizer
3. Java regular Expression
4. Wikipedia : Regular Expression