Exploring Java Long Hashcode Implementation

Introduction

The hashCode() method is used by Java to compute a numerical representation (hash value) of an object. For the Long class, the hashCode() method returns the hash code value of the object. In this lab, you will learn how to use the hashCode() method of the Long class in Java.

Creating a Java file

In this step, you will create a new file in the project directory and name it LongHashCode.java.

cd ~/project
touch LongHashCode.java

Importing Required Package

In this step, you will import the required Java package java.lang which includes the Long class.

import java.lang.*;

Using the hashCode() Method

In this step, you will create an object of the Long class and use the hashCode() method to get a hash code of that object.

Long number = 100L;
int hash = number.hashCode();
System.out.println("Hash code: " + hash);

Here, we first create an object of the Long class named number with a value of 100L. Then we use the hashCode() method to calculate the hash value of this object. Finally, we print the calculated hash value.

Creating a User Input

In this step, you will create a user input that takes a Long value from the user, and then use the hashCode() method to calculate its hash value.

Scanner scanner = new Scanner(System.in);
System.out.print("Enter a Long value: ");
Long userInput = scanner.nextLong();
int hash = userInput.hashCode();
System.out.println("Hash code: " + hash);

Here, we created a scanner object to take the input from the user. Then, we prompt the user to enter a Long value. Once the user enters the value, we store it in the userInput variable. Then we use the hashCode() method to calculate the hash value of this object. Finally, we print the calculated hash value.

Testing with Negative Value

In this step, you will test the program with a negative value.

Long number = -100L;
int hash = number.hashCode();
System.out.println("Hash code: " + hash);

Testing with Zero Value

In this step, you will test the program with a zero value.

Long number = 0L;
int hash = number.hashCode();
System.out.println("Hash code: " + hash);

Compiling and Running the Program

In this step, you will compile the Java program using the following command:

javac LongHashCode.java

Now, you can execute the program using the following command:

java LongHashCode

When you run the program, it prompts you to enter a Long value. Once you enter a value, it calculates and prints the hash value of the entered value.

Program Output

The program output will vary depending on the input value. Here is an example output for the value 123456789L:

Enter a Long value: 123456789
Hash code: 123456789

Summary

In this lab, you learned how to use the hashCode() method of the Long class in Java to calculate the hash value of an object. You also learned how to take user input, compile, and run the Java program.