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Java 8 | BigInteger longValueExact() Method with Examples

Last Updated : 04 Dec, 2018
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java.math.BigInteger.longValueExact() was introduced in Java 8. It is an inbuilt function which converts the value of BigInteger to a long and checks for lost information. If the value of BigInteger is greater than 9,223,372,036,854,775,807 or less than -9,223,372,036,854,775,808; the method will throw ArithmeticException as BigInteger doesn’t fit in long range. Syntax:
public long longValueExact()
Return Value: This method returns the long value of this BigInteger. Exception: The method throws ArithmeticException if the value of BigInteger is greater than 9,223,372,036,854,775,807 or less than -9,223,372,036,854,775,808; as this range doesn’t fit in long range. Example:
 Input: 98169894145 Output: 98169894145 Explanation: 98169894145 is given as input which is BigInteger and long value of 98169894145 is 98169894145 Input: -65416518651 Output: -65416518651 Explanation: -65416518651 is given as input which is BigInteger and long value of -65416518651 is -65416518651 Input: 10000000000000000000 Output: ArithmeticException Explanation: When 10000000000000000000 is tried to convert to long, since 10000000000000000000 > 9,223,372,036,854,775,807 (greater than a long's range), therefore it throws an arithmetic exception. 
Below programs illustrates longValueExact() method of BigInteger class: Program 1: To demonstrate longValueExact() method for positive number <9,223,372,036,854,775,807 Java
// Java program to demonstrate longValueExact() // method of BigInteger Class import java.math.*; public class GFG {  public static void main(String[] args)  {  // Creating a BigInteger object  BigInteger big;  big = new BigInteger("98169894145");  // print value of BigInteger  System.out.println("BigInteger value : "  + big);  // convert big to the long value  long b1 = big.longValueExact();  // print long value  System.out.println("long converted value : "  + b1);  } } 
Output:
 BigInteger value : 98169894145 long converted value : 98169894145 
Program 2: To demonstrate longValueExact() method for negative number >-9,223,372,036,854,775,808 Java
// Java program to demonstrate longValueExact() // method of BigInteger Class import java.math.*; public class GFG {  public static void main(String[] args)  {  // Creating a BigInteger object  BigInteger big = new BigInteger("-65416518651");  // print value of BigInteger  System.out.println("BigInteger value : "  + big);  // convert big to the long value  long b1 = big.longValueExact();  // print long value  System.out.println("long converted value : "  + b1);  } } 
Output:
 BigInteger value : -65416518651 long converted value : -65416518651 
Program 3: To demonstrate longValueExact() method for negative number <-9,223,372,036,854,775,808. It will throw Arithmetic Exception Java
// Java program to demonstrate longValueExact() // method of BigInteger Class import java.math.*; public class GFG {  public static void main(String[] args)  {  // Creating a BigInteger object  BigInteger big = new BigInteger("-10000000000000000000");  // print value of BigInteger  System.out.println("BigInteger value : "  + big);  try {  // convert big to the long value  long b1 = big.longValueExact();  // print long value  System.out.println("long converted value : "  + b1);  }  catch (Exception e) {  System.out.println("Exception: " + e);  }  } } 
Output:
 BigInteger value : -10000000000000000000 Exception: java.lang.ArithmeticException: BigInteger out of long range 
Program 4: To demonstrate longValueExact() method for positive number >9,223,372,036,854,775,807. It will throw Arithmetic Exception Java
// Java program to demonstrate longValueExact() // method of BigInteger Class import java.math.*; public class GFG {  public static void main(String[] args)  {  // Creating a BigInteger object  BigInteger big = new BigInteger("10000000000000000000");  // print value of BigInteger  System.out.println("BigInteger value : "  + big);  try {  // convert big to the long value  long b1 = big.longValueExact();  // print long value  System.out.println("long converted value : "  + b1);  }  catch (Exception e) {  System.out.println("Exception: " + e);  }  } } 
Output:
 BigInteger value : 10000000000000000000 Exception: java.lang.ArithmeticException: BigInteger out of long range 
Reference: https://docs.oracle.com/javase/8/docs/api/java/math/BigInteger.html#longValueExact--

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