ExampleHashCode.java

// More about hash code
import java.util.*;
import java.lang.*;

public class Example
{
  public int x;
  
  public Example(int x) {
  	this.x = x;  
  }
  
  public static void main(String[] args)
  {
    Set<Example> set = new HashSet<>();
    long startTime = System.nanoTime();    

    Example last = null;
    for (int i=0; i < 10; i++) {
      	last = new Example(i);
    	set.add(last);
    }
    long estimatedTime = System.nanoTime() - startTime;
    System.out.println(set.size());
    System.out.println((double)estimatedTime / 1000000000.0);
    
    Example other = new Example(-1);
    System.out.println(set.contains(other));
  }
  
  public int hashCode() {
  	return 2;  
  }
  
  public boolean equals(Object a) {
    Example aE = (Example) a;
  	System.out.println("equals " + this.x + " " + aE.x);
    return super.equals(a);
  }
  
}