Convert String to int in Java

In order to convert a String to int in Java Programming language you can follow the below code examples,

1. Using Interger.parseInt(String str) method

   class StringToIntegerExample {
   
   	public static void main(String[] args) {
   		
   		String stringInt = "25"; //A String variable holding an int value.
   		int intValue = Integer.parseInt(stringInt); 
   		
   		System.out.println(intValue); //Prints out 25
   	}
   }

   But its always better to surround this code with a try catch block as it can throw NumberFormatException if your String object is not holding a integer value, try replacing stringInt from 25 to A25, run the code and you will get the below error stack trace.

   Exception in thread "main" java.lang.NumberFormatException: For input string: "A25"
   	at java.base/java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)
   	at java.base/java.lang.Integer.parseInt(Integer.java:652)
   	at java.base/java.lang.Integer.parseInt(Integer.java:770)
   	at StringToIntegerExample.main(Client.java:6)

   Let's put the above code in try/catch block:

   class StringToIntegerExample {
   
   public static void main(String[] args) {
   
   	String stringInt = "A25";
   	try {
   		int intValue = Integer.parseInt(stringInt);
   		System.out.println(intValue);
   	} catch (Exception e) {
   		System.out.println("Cannot convert " + stringInt
   				+ " to integer as not a number!");
   	}
    }
   }



2. Using Integer.valueOf(String str) method

   class StringToIntegerExample {
   
   /**
    * Example:
    * String to integer using
    * Integer.valueOf(String str)
    * 
    * @param args
    */
   public static void main(String[] args) {
   
   	String stringInt = "300";
   
   	try {
   		int intValue = Integer.valueOf(stringInt);
   		System.out.println(intValue);
   	} catch (Exception e) {
   		System.out.println("Cannot convert " + stringInt
   				+ " to integer as not a number!");
   	}
   }
   }