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Java SE 7 Programmer II (1Z0-804)

Question : 3

Total: 8

Given:

class MyKeys {   
 Integer key;   
 MyKeys(Integer k) {   
  key = k;   
 }   
 public boolean equals(Object o) {   
  return ((MyKeys) o).key == this.key;   
 }   
}

And this code snippet:


Map m = new HashMap();  
MyKeys m1 = new MyKeys(1);  
MyKeys m2 = new MyKeys(2);  
MyKeys m3 = new MyKeys(1);  
MyKeys m4 = new MyKeys(new Integer(2));  
m.put(m1, "car");  
m.put(m2, "boat");  
m.put(m3, "plane");  
m.put(m4, "bus");  
System.out.print(m.size());

What is the result?

2
3
4
Compilation fails

Validate

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