To convert String to int in Java you can use one of the following options-
- Integer.parseInt(String str) method which returns the passed String as int.
- Integer.valueOf(String str) method which returns the passed String as Integer.
Java example to convert String to int using Integer.parseInt()
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public class StringToInt { public static void main(String[] args) { String str = "12"; try{ int num = Integer.parseInt(str); System.out.println("value - " + num); // can be used in arithmetic operations now System.out.println(num+"/3 = " + num/3); }catch(NumberFormatException exp){ System.out.println("Error in conversion " + exp.getMessage()); } } } |
Output
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value - 12 12/3 = 4 |
Java example to convert String to int using Integer.valueOf
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public class StringToInt { public static void main(String[] args) { String str = "12"; try{ Integer num = Integer.valueOf(str); System.out.println("value - " + num); // can be used in arithmetic operations now System.out.println(num+"/3 = " + num/3); }catch(NumberFormatException exp){ System.out.println("Error in conversion " + exp.getMessage()); } } } |
Output
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value - 12 12/3 = 4 |
In this example you can see that valueOf() method returns Integer object, because of autoboxing it can directly be used as int value though.
NumberFormatException
In the examples you can see a try-catch block which catches NumberFormatException which is thrown if an invalid number string is passed for converting to int.
Java example
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public class StringToInt { public static void main(String[] args) { String str = "123ab"; try{ Integer num = Integer.valueOf(str); System.out.println("value - " + num); // can be used in arithmetic operations now System.out.println(num+"/3 = " + num/3); }catch(NumberFormatException exp){ System.out.println("Error in conversion " + exp.getMessage()); throw exp; } } } |
Output
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Error in conversion For input string: "123ab" Exception in thread "main" java.lang.NumberFormatException: For input string: "123ab" at java.lang.NumberFormatException.forInputString(Unknown Source) at java.lang.Integer.parseInt(Unknown Source) at java.lang.Integer.valueOf(Unknown Source) at com.knpcode.programs.StringToInt.main(StringToInt.java:8) |
That’s all for the topic How to Convert String to int in Java. If something is missing or you have something to share about the topic please write a comment.
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