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String to int in Java

String to int in Java

Last Updated : 22 Nov, 2024

Converting a String to an int in Java can be done using methods provided in the Integer class, such as Integer.parseInt() or Integer.valueOf() methods.

Example:

The most common method to convert a string to a primitive int is Integer.parseInt(). It throws a NumberFormatException if the string contains non-numeric characters.

Java

// Java Program to demonstrate  // String to int conversion using parseInt() public class StringToInt {     public static void main(String[] args) {                String s = "12345";           // Convert the string to an integer          // using Integer.parseInt()         int n = Integer.parseInt(s);          System.out.println("" + n);     } }

Output

Other Ways to Convert String to int

Using Integer.valueOf() Method

The Integer.valueOf() method converts a String to an Integer object instead of a primitive int. We can unbox it to an int.

Note: valueOf() method uses parseInt() internally to convert to integer.

Example:

Java

// Java ProgramConvert String to int  // using Integer.valueOf() Method public class StringToInt {         public static void main(String[] args) {                // Convert String to Integer using valueOf()         String s = "217";                // Convert the string to an Integer object          // using Integer.valueOf()         int n = Integer.valueOf(s);                  System.out.println("" + n);     } }

Output

Handling Errors for Non-Numeric Strings

If a string literal does not contain numeric values, calling the Integer.parseInt() or Integer.valueOf() methods will result in a NumberFormatException.

Example:

Java

// Java Program to Demonstrate Working of parseInt() Method // where NumberFormatException is Thrown public class StringToIntExample {      public static void main(String[] args) {                  // NumberFormatException due to empty string         String s1 = "";         int n1 = Integer.parseInt(s1);                   // NumberFormatException due to non-numeric string         String s2 = "geeksforgeeks";         int n2 = Integer.parseInt(s2);           System.out.println(n1);         System.out.println(n2);     } }

Output:

Exception in thread "main" java.lang.NumberFormatException: For input string: "" 	at java.base/java.lang.NumberFormatException.forInputString(NumberFormatException.java:65) 	at java.base/java.lang.Integer.parseInt(Integer.java:662) 	at java.base/java.lang.Integer.parseInt(Integer.java:770) 	at StringToIntExample.main(StringToIntExample.java:10)

String to int in Java

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