How do I convert a String to an int in Java

Question

My String contains only numbers, and I want to return the number it represents.

For example, given the string "1234" the result should be the number 1234.

How can I convert a String to an int in Java?

Answer 1

Hello @kartik,

We can use the parseInt(String str) method of the Integer wrapper class for converting a String value to an integer value.

For example:

String strValue = "12345";
Integer intValue = Integer.parseInt(strVal);

The Integer class also provides the valueOf(String str) method:

String strValue = "12345";
Integer intValue = Integer.valueOf(strValue);

We can also use toInt(String strValue) of NumberUtils Utility Class for the conversion:

String strValue = "12345";
Integer intValue = NumberUtils.toInt(strValue);

Hope it helps!!

Become certified expert with Java certification here.

Thank you!

Answer 2

Use the lines of code mentioned below:-

String myString = "1234"; 
int foo = Integer.parseInt(myString);

The documentation of Java mentions that the "catch" is when this function can throw a NumberFormatException, which you can handle by using the code mentioned below:
 

int foo; 
try { 
    foo = Integer.parseInt(myString); 
} 
catch (NumberFormatException e) { 
  foo = 0; 
}

This will ensure that they default a malformed number to 0, but you could try another way if wished upon. However, you can also use an Ints method from the Guava library, which is in combination with Java 8's Optional and hence, this makes a more powerful and concise way to convert a string into an int:
 

import com.google.common.primitives.Ints; 

int foo = Optional.ofNullable(myString) 
.map(Ints::tryParse) 
.orElse(0)