JAVA EXAMPLE PROGRAMS

JAVA EXAMPLE PROGRAMS

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Program: How to validate IP address using regular expression?


Description:

Below example gives sample code for validation IP address using regular expression.


Code:
package com.java2novice.regex;

import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class MyIpMatch {

	public static boolean isValidIP(String ipAddr){
		
		Pattern ptn = Pattern.compile("^(\\d{1,3})\\.(\\d{1,3})\\.(\\d{1,3})\\.(\\d{1,3})$");
		Matcher mtch = ptn.matcher(ipAddr);
		return mtch.find();
	}

	public static void main(String a[]){
		System.out.println("10.23.45.12 is valid? "+MyIpMatch.isValidIP("10.23.45.12"));
		System.out.println("10.2a.56.32 is valid? "+MyIpMatch.isValidIP("10.2a.56.32"));
		System.out.println("10.23.45 is valid? "+MyIpMatch.isValidIP("10.23.45"));
	}
}

Output:
10.23.45.12 is valid? true
10.2a.56.32 is valid? false
10.23.45 is valid? false
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Knowledge Centre
Difference between while and do-while
The while statement verifies the condition before entering into the loop to see whether the next loop iteration should occur or not. The do-while statement executes the first iteration without checking the condition, it verifies the condition after finishing each iteration. The do-while statement will always execute the body of a loop at least once.
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About Author

I'm Nataraja Gootooru, programmer by profession and passionate about technologies. All examples given here are as simple as possible to help beginners. The source code is compiled and tested in my dev environment.

If you come across any mistakes or bugs, please email me to [email protected].

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Reference: Java™ Platform Standard Ed. 7 - API Specification | Java™ Platform Standard Ed. 8 - API Specification | Java is registered trademark of Oracle.
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