Java Program to Convert String to Int

Write a Java program to convert string to int or integer. In this Java programming language, we can use parseInt and valueOf methods to convert a string to an integer or int. In this example, we use the parseInt method.

package NumPrograms;

public class StringToInt1 {
	
	public static void main(String[] args) {
		
		String s1 = "2020";
		String s2 = "10";
		
		int x = Integer.parseInt(s1);
		int y = Integer.parseInt(s2);

		System.out.println(x);
		System.out.println(y);
	}
}

Java Program to Convert String to Int

Let me perform the addition before and after converting the string to an integer.

package NumPrograms;

public class StringToInt2 {
	
	public static void main(String[] args) {
		
		String s1 = "1040";
		
		int x = Integer.parseInt(s1);

		System.out.println(s1 + 50);
		System.out.println(x + 50);
	}
}

104050
1090

This Java example uses the valueOf method to convert the string to an integer.

package NumPrograms;

public class StringToInt3 {
	
	public static void main(String[] args) {
		
		String s1 = "2000";
		
		int x = Integer.valueOf(s1);
		System.out.println(x);
		
		System.out.println(s1 + 150);
		System.out.println(x + 150);
	}
}

2000
2000150
2150

Let us try to convert the string text to an integer using parseInt. It will throw the exception.

package NumPrograms;

public class StringToInt4 {
	
	public static void main(String[] args) {
		
		String s1 = "tutorialgateway";
		
		int x = Integer.parseInt(s1);
		System.out.println(x);
	}
}

Exception in thread "main" java.lang.NumberFormatException: For input string: "tutorialgateway"
	at java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)
	at java.lang.Integer.parseInt(Integer.java:580)
	at java.lang.Integer.parseInt(Integer.java:615)
	at NumPrograms.StringToInt4.main(StringToInt4.java:9)

Trying to convert string text to int using the valueOf, and the program throws the error.

package NumPrograms;

public class StringToInt5 {
	
	public static void main(String[] args) {
		
		String s1 = "Java Programs";
		
		int x = Integer.valueOf(s1);
		System.out.println(x);
		
	}
}

Exception in thread "main" java.lang.NumberFormatException: For input string: "Java Programs"
	at java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)
	at java.lang.Integer.parseInt(Integer.java:580)
	at java.lang.Integer.valueOf(Integer.java:766)
	at NumPrograms.StringToInt5.main(StringToInt5.java:9)

This Java example accepts the user input string value and converts it to an integer using valueOf and parseInt functions.

package NumPrograms;

import java.util.Scanner;

public class StringToInt6 {
	private static Scanner sc;
	
	public static void main(String[] args) {
		
		String s1;
		sc= new Scanner(System.in);

		System.out.print("Please Enter any Text =  ");
		s1 = sc.nextLine();
	
		int x = Integer.valueOf(s1);
		System.out.println("valueOf(s1) result  = " + x);
		
		int y = Integer.parseInt(s1);
		System.out.println("parseInt(s1) result = " + y);
	}
}

Please Enter any Text =  13476
valueOf(s1) result  = 13476
parseInt(s1) result = 13476