Java - Integer parseInt() method

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Description

The Java Integer parseInt(String s, int radix) method parses the string argument s as a signed integer in the radix specified by the second argument radix. Some examples can be seen here −

parseInt("0", 10) returns 0
parseInt("222", 10) returns 222
parseInt("-0", 10) returns 0
parseInt("-BB", 16) returns -187
parseInt("1010110", 2) returns 86
parseInt("2147483647", 10) returns 2147483647
parseInt("-2147483648", 10) returns -2147483648
parseInt("2147483648", 10) throws a NumberFormatException
parseInt("99", 8) throws a NumberFormatException
parseInt("Kona", 10) throws a NumberFormatException
parseInt("ADMIN", 27) returns 5586836

Declaration

Following is the declaration for java.lang.Integer.parseInt() method

public static int parseInt(String s, int radix) throws NumberFormatException

Parameters

• s − This is a String containing the integer representation to be parsed.

• radix − This is the radix to be used while parsing s.

Return Value

This method returns the integer represented by the string argument in the specified radix.

Exception

NumberFormatException − if the string does not contain a parsable int.

Getting Decimal int from a String having Positive int Value Example

The following example shows the usage of Integer parseInt() method to parse a Integer object from a string containing decimal number. We've created a String variable and assign it a string containing decimal number. Then using parseInt method, we're obtaining the Integer object and printing it.

package com.tutorialspoint;
public class IntegerDemo {
   public static void main(String[] args) {   
      String str = "50";
      /* returns an Integer object holding the int value represented
         by string str */
      System.out.println("Number = " + Integer.parseInt(str, 10)); 
   }
}

Output

Let us compile and run the above program, this will produce the following result −

Number = 50

Getting Octal Integer from a String having Positive int Value Example

The following example shows the usage of Integer parseInt() method to get a Integer object from a string containing a octal number. We've created a String variable and assign it a string containing an octal number. Then using parseInt method, we're obtaining the Integer object and printing it.

package com.tutorialspoint;
public class IntegerDemo {
   public static void main(String[] args) {    
      String str = "50";
      /* returns an Integer object holding the octal int value represented
         by string str */
      System.out.println("Number = " + Integer.parseInt(str,8)); 
   }
}

Output

Let us compile and run the above program, this will produce the following result −

Number = 40

Getting Hexadecimal Integer from a String having Positive int Value Example

The following example shows the usage of Integer parseInt() method to get a Integer object from a string containing a hexadecimal number. We've created a String variable and assign it a string containing an hexadecimal number. Then using parseInt method, we're obtaining an Integer object and printed.

package com.tutorialspoint;
public class IntegerDemo {
   public static void main(String[] args) {    
      String str = "50";
      /* returns an Integer object holding the hexadecimal int value represented
         by string str */
      System.out.println("Number = " + Integer.parseInt(str,16)); 
   }
}

Output

Let us compile and run the above program, this will produce the following result −

Number = 80