Java Integer parseInt() Method
The
parseInt()
method is a method of
Integer class
under
java.lang
package. There are
three
different types of
Java
Integer
parseInt ()
methods which can be differentiated depending on its parameter.
These are:
Java Integer parseInt (String s) Method
Java Integer parseInt (String s, int radix) Method
a Integer parseInt(CharSequence s, int beginText, int endText, int radix)
1. Java Integer parseInt (String s) Method
This method parses the
String
argument
as a
signed decimal
integer object. The characters in the string must be decimal digits, except that the
first
character of the string may be an ASCII
minus
sign '-' to indicate a negative value or an ASCII
plus
'+' sign to indicate a positive value. It returns the integer value which is represented by the argument in a decimal integer.
2. Java Integer parseInt (String s, int radix) Method
This method parses the
String
argument as a
signed decimal
integer object in the specified
radix
by the second argument. The characters in the string must be decimal digits of the specified argument except that the
first
character may be an ASCII
minus
sign '-' to indicate a negative value or an ASCII
plus
sign '+' to indicate a positive value. The resulting integer value is to be returned.
3. Java Integer parseInt (CharSequence s, int beginText, int endText, int radix)
This method parses the
CharSequence
argument as a
signed
integer in the specified
radix
argument, beginning at the specified
beginIndex
and extending to
endIndex - 1
. This method does not take steps to guard against the CharSequence being mutated while parsing.
Syntax:
Following are the declarations of
parseInt ()
method:
public static int parseInt (String s)
public static int parseInt (String s, int radix)
public static int parseInt (CharSequence s, int beginIndex, int endIndex, int radix)
Parameter:
DataType
Parameter
Description
Required/Optional
String
It is a String which needs to be converted into the Integer equivalent.
Required
radix
The radix to be used while parsing the String
Required
beginIndex
The beginning index, inclusive.
Required
endIndex
The ending index, exclusive.
Required
CharSequence
It is the CharSequence which needs to be converted into the Integer equivalent.
Required
Returns:
Method
Returns
parseInt (String s)
This method returns the integer value which is represented by the argument in decimal equivalent.
parseInt (String s, int radix)
This method returns the integer value which is represented by the string argument in the specified radix.
parseInt (String s, int radix)
This method returns the integer value which is represented by the string argument in the specified radix.
Exceptions:
NullPointerException:
If s is null.
IndexOutOfBoundsException:
If beginIndex is negative, or if beginIndex is greater than endIndex or if endIndex is greater than s.length ().
NumberFormatException:
If the CharSequence does not contain a parsable int in the specified radix, or if radix is either smaller than Character.MIN_RADIX or larger than Character.MAX_RADIX.
Compatibility Version:
Java 1.2 and above:
Java Integer parseInt (String s)
Java Integer parseInt (String s, int radix)
Java 9:
Java Integer parseInt (CharSequence s, int beginText, int endText, int radix)
Example 1
public class IntegerParseIntExample1 {
public static void main(String[] args) {
int decimalExample = Integer.parseInt("20");
int signedPositiveExample = Integer.parseInt("+20");
int signedNegativeExample = Integer.parseInt("-20");
System.out.println("Value = "+decimalExample);
System.out.println("Value = "+signedPositiveExample);
System.out.println("Value = "+signedNegativeExample);
Test it Now
Output:
Value = 20
Value = 20
Value = -20
Example 2
public class IntegerParseIntRadixExample2 {
public static void main(String[] args) {
int a = Integer.parseInt("150", 8);
int b = Integer.parseInt("+200", 16);
int c = Integer.parseInt("-344", 12);
System.out.println("Value = "+a);
System.out.println("Value = "+b);
System.out.println("Value = "+c);
Test it Now
Output:
Value = 104
Value = 512
Value = -484
Example 3
public class IntegerParseIntExample3 {
public static void main(String[] args) {
String s="200";
int i=Integer.parseInt(s);
System.out.println(s+100);//200100 because + is string concatenation operator
System.out.println(i+100);//300 because + is binary plus operator
Test it Now
Output:
200100
Example 4
public class IntegerParseIntExample4 {
public static void main(String[] args) {
String s = "100";
// 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());
Test it Now
Output:
int i = 100
Example 5
public class IntegerParseIntExample5 {
public static void main(String[] args) {
String number = "10A";
int result = Integer.parseInt(number);
System.out.println(result);
Test it Now
Output:
Exception in thread "main" java.lang.NumberFormatException: For input string: "10A"
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 myPackage.IntegerParseIntExample5.main(IntegerParseIntExample5.java:6)
Next Topic
parseUnsignedInt() Method
