How to convert a String into an int in Java

With Java 11, there are several ways to convert an int to a String type. Use the parseInt method of the Java Integer class to translate a string to an integer. If the string cannot be converted into an int, the function attempts to convert it to an int and raises a NumberformatException. In this blog, we are going to learn about converting the String into an int in Java.

For converting a String value to an integer value, we can utilize the parseInt(String str) method of the Integer wrapper class. With Java 11, there are several ways to convert an int to a String type:

1. Integer.parseInt()

   String str = "1234";
   int result = Integer.parseInt(str);

2. Integer.valueOf()

   String str = "1234";
   int result = Integer.valueOf(str).intValue();

3. Integer constructor

   String str = "1234";
   Integer result = new Integer(str);

4. Integer.decode

   String str = "1234";
   int result = Integer.decode(str);

Use the parseInt method of the Java Integer class to translate a string to an integer. If the string cannot be transformed into an int type, the parseInt function attempts to convert the string to an int and raises a NumberFormatException.

Despite whatever exceptions it might throw, use this:

int i = Integer.parseInt(myString);

If the String represented by the variable myString is an acceptable integer, such as “1234”, “200,” or “1,” it will be transformed to a Java int. The code should be a little bit longer to account for this as if it fails for any reason, the update may throw a NumberFormatException.

To avoid a NumberFormatException, check the Java String to Int conversion function, for instance.

public class BehindJava {
	public static void main(String[] args) {
		// String s = "test"; // Use this if you want to test the exception below
		String s = "1234";

		try {
			// The String to int conversion happens here
			int i = Integer.parseInt(s.trim());

			// Print out the value after the conversion
			System.out.println("int i = " + i);
		} catch (NumberFormatException nfe) {
			System.out.println("NumberFormatException: " + nfe.getMessage());
		}
	}
}

Output:

int i = 1234

The Integer parseInt process will throw a NumberFormatException if the change attempt fails, in this case if you try to convert the Java String test to an int. You must handle this exception in a try/catch block.