parseInt() in Java - Scaler Topics

Overview

The method parseInt() belongs to the Integer class which is under java.lang package. It is used to parse the string value as a signed decimal value. It is used in Java for converting a string value to an integer by using the method parseInt().

Syntax of parseInt() in Java

Following is how the parseInt() method can be declared in java:

Parameters of parseInt() in Java

Data type	Parameter	Description
int	startIndex	It is the starting index of the string and is inclusive.
int	endIndex	It is the ending index of the string and is exclusive.
int	radix	It represents the base of the number in the string.
String	s	The string that is to be converted into an integer.
CharSequence	s	It is the sequence of characters that is to be converted to an integer.

Return Values of parseInt() in Java

Method name	Return
parseInt(String s)	Returns an integer value in its decimal equivalent
parseInt(String s, int radix)	Returns an integer value with base specified as radix.

Note :
Radix is the parameter that specifies the number system to be used.

For example, binary = 2, octal = 8, hexadecimal = 16, etc.

Exceptions of parseInt() in Java

There are three types of exceptions possible by using the method parseInt() in java.

NullPointerException: It arises when the string s given as argument is null.

IndexOutOfBoundsException: It arises when:

startIndex is negative
startIndex > endIndex
endIndex > s.length (length of given string)

NumberFormatException: It occurs when:

CharSequence does not contain parsable int at a specified radix
radix $<$ Character.MIN_RADIX
radix $>$ Character.MAX_RADIX

Note:

Example of parseInt() in Java

Output:

More Examples

Example 1

Two strings are passed and are returned as their respective signed decimal Integer objects

Output:

Example 2

A user-defined example where anyone using this code can put a value of their choice and get the equivalent integer as output.

Output:

Explanation:

Here, trim() is used to removed ending spaces from the left and right sides.
These spaces otherwise, can cause NumberFormatException in Java.

Conclusion

The method parseInt() belongs to the Integer class which is under java.lang package. It is used to parse the string value as a signed decimal value.
Following are how the parseInt() method can be declared in java :
- public static int parseInt (String s).
- public static int parseInt (String s, int radix).
- public static int parseInt (CharSequence s, int startIndex, int endIndex, int radix).
It is used in java for converting a string value to an integer by using the method parseInt().
The parseInt() method throws three exceptions: NullPointerException, IndexOutOfBoundsException, NumberFormatException when the input arguments are not according to the conventions.