JAVA PROGRAM • LEVEL 09 — CLASSES, OBJECTS & CONSTRUCTORS
Implement Object Equality in Java
Learn implement object equality in java with a complete, compiler-ready Java 17 example.
PROBLEM UNDERSTANDING
Input and expected output
No input required
true
COMPLETE JAVA 17 PROGRAM
Complete Java 17 implementation
import java.util.Objects;
class Student { int id; Student(int id){this.id=id;} public boolean equals(Object other){return other instanceof Student s&&id==s.id;} public int hashCode(){return Objects.hash(id);} }
class Main { public static void main(String[] args){System.out.println(new Student(7).equals(new Student(7)));} }CURRENT STEP
Select Start to walk through the important lines.
SELECTED LINE
No line selected
EXPECTED OUTPUT FOR THE SAMPLE
true
PROGRAM EXPLANATION
Algorithm and explanation
- Initialize the deterministic sample values used for implement object equality in java.
- Create the required object and apply equals() and hashCode() to its state or behavior.
- Print the final result and compare it with the documented sample output.
This Java 17 example demonstrates equals() and hashCode() through a complete, executable program. The values are intentionally small so students can trace each statement, verify the output, and then modify the example safely in the online compiler.
EFFICIENCY
Time and space complexity
O(1)
O(1)
DEBUGGING CHECKLIST
Common mistakes
Keep the class name Main and the entry method signature public static void main(String[] args) when using the online compiler.
Create an object before accessing instance members; static members can be accessed through the class name.
Java is case-sensitive, and every statement that requires a semicolon must end with one.