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  1. /* package whatever; // don't place package name! */
  2.  
  3. import java.util.*;
  4. import java.lang.*;
  5. import java.io.*;
  6.  
  7. /* Name of the class has to be "Main" only if the class is public. */
  8. class Ideone
  9. {
  10. 	public static void main (String[] args) throws java.lang.Exception
  11. 	{
  12. 		Vector2d obj1 = new Vector2d(2,3);
  13. 		Vector2d obj2 = null;
  14.  
  15. 		System.out.println(obj1.equals(obj2));
  16. 	}
  17.  
  18.     private static class Vector2d {
  19.     	int x;
  20.     	int y;
  21.  
  22.         public Vector2d(int x, int y) {
  23.         	this.x = x;
  24.         	this.y = y;
  25.         }
  26.  
  27. 	    @Override
  28. 	    public boolean equals(Object other){
  29. 	        if (!(other instanceof Vector2d)){
  30. 	            return false;
  31. 	        } else {
  32. 	            return equals((Vector2d) other);
  33. 	        }
  34. 	    }
  35.  
  36. 	    public boolean equals(Vector2d other){
  37. 	        return this.x == other.x && this.y == other.y;
  38. 	    }
  39.     }	
  40.  
  41. }
Runtime error #stdin #stdout #stderr 0.08s 47128KB
comments (?)
stdin 
Standard input is empty
stdout 
Standard output is empty
stderr 
Exception in thread "main" java.lang.NullPointerException
	at Ideone$Vector2d.equals(Main.java:37)
	at Ideone.main(Main.java:15)
https://ideone.com/bHit0T
language:
Java (HotSpot 12)
created:
2 years ago
visibility:
public

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