• Home
  • Ubuntu 18.04
    • Whats New?
    • Upgrade Ubuntu
    • Install Java
    • Install Node.js
    • Install Docker
    • Install Git
    • Install LAMP Stack
  • Tutorials
    • AWS
    • Shell Scripting
    • Docker
    • Git
    • MongoDB
  • Funny Tools
  • FeedBack
  • Submit Article
  • About Us
TecAdmin
Menu
  • Home
  • Ubuntu 18.04
    • Whats New?
    • Upgrade Ubuntu
    • Install Java
    • Install Node.js
    • Install Docker
    • Install Git
    • Install LAMP Stack
  • Tutorials
    • AWS
    • Shell Scripting
    • Docker
    • Git
    • MongoDB
  • Funny Tools
  • FeedBack
  • Submit Article
  • About Us

How to Convert String to int in Java

Written by Rahul, Updated on August 3, 2018

Java is an object orientied programming languege. In Java you can use Integer.parseInt() or Integer.valueOf() functions to convert String value to an int value. In any case String is not a convertible then NumberFormatException will occur.

#1. Using Integer.parseInt()

Integer.parseInt() converts string value and returns an int primitive as result. For below example, first, we store 5 as a string value to id variable. Then convert it to integer and save to result variable.

1
2
3
4
5
6
7
8
9
class ConvertStringToInt1 {
 
public static void main(String args[]){
String id = "5";
int result = Integer.parseInt(id);
System.out.println(result);
}
}

Save the above content in ConvsertStringToInt1.java file and compile and run this program.

Compile:

javac ConvertStringToInt1.java

Run:

java ConvertStringToInt1

5

#2. Using Integer.valueOf()

Integer.valueOf() also uses Integer.parseInt function in backend but in result, it provides and Integer object value.

1
2
3
4
5
6
7
8
9
class ConvertStringToInt2 {
 
public static void main(String args[]){
String id = "5";
Integer result = Integer.valueOf(id);
System.out.println(result);
}
}

Save the above content in ConvsertStringToInt2.java file and compile and run this program.

Compile:

javac ConvertStringToInt2.java

Run:

java ConvertStringToInt2

5

#3. Exception in Conversion

If the given input is not parsable by the any of the above methods, NumberFormatException will be thrown. As in the below example, we are storing string”5abc” in id variable which contains alphabets. If we try to convert this number to int, NumberFormatException exception will occur.

1
2
3
4
5
6
7
8
9
10
11
12
13
14
class ConvertStringToInt3 {
 
public static void main(String args[]) {
String id = "5abc";
try{
int result = Integer.parseInt(id);
System.out.println(result);
}catch(NumberFormatException e){
System.out.println(e);
}
}
}

Save the above content in ConvsertStringToInt3.java file and compile and run this program.

Compile:

javac ConvertStringToInt3.java

Run:

java ConvertStringToInt3

java.lang.NumberFormatException: For input string: "5abc"

Reference:

http://docs.oracle.com/javase/8/docs/api/java/lang/Integer.html

Share it!
Share on Facebook
Share on Twitter
Share on LinkedIn
Share on Reddit
Share on Tumblr
Share on Whatsapp
Rahul
Rahul
Connect on Facebook Connect on Twitter

I, Rahul Kumar am the founder and chief editor of TecAdmin.net. I am a Red Hat Certified Engineer (RHCE) and working as an IT professional since 2009..

1 Comment

  1. Avatar kavya Reply
    May 10, 2018 at 9:24 am

    How to convert string to int in java 8
    In Java 8 using stream API we can convert set of String to set of Integer, it involves following steps like,

    1. The Set.Stream() is used to convert set to stream.

    2. The Steam.map() is used to convert stream to stream.

    3. The Collectorts.toset() is used to Accumulate stream to set.

    4. The map() operation is used to throw NumberFormatException, if string does not contains parsable integer.

Leave a Reply Cancel reply

Popular Posts

  • How To Install Python 3.9 on Ubuntu 20.04 5
  • How To Install Python 3.9 on Ubuntu 18.04 0
  • How to Use AppImage on Linux (Beginner Guide) 2
  • How to Install Python 3.9 on CentOS/RHEL 7 & Fedora 32/31 0
  • How To Install VNC Server on Ubuntu 20.04 1
© 2013-2020 Tecadmin.net. All Rights Reserved | Terms  | Privacy Policy