Puzzle 47 - Solution

There are different categories of solutions to this puzzle, with the most simplest placed first to the most difficult!

1. DataType1 - Datatype4 all have different values and we rely on autoboxing and numeric promotions to get the job done.

package com.twister;
public class Mystery {

 public static boolean isEqual(Integer f1,Long f2){
     return f1.equals(f2);
 }

 public static void main(String[] args) {
     int f1 = 1;
      long f2 = 1;
  
     System.out.println("f1 is equals to f2 : "+ (f1==f2));//prints true
        System.out.println("f1 is equals to

f2 : "+ isEqual(f1,f2));//prints false
    }

}

2. DataType1 - Datatype2 are same and Datatype3 - Datatype4 are the same. Relies on autoboxing and the fact that the equals method of Float treats +0 as not equal to -0.

package com.twister;
public class Mystery {

 public static boolean isEqual(Float f1, Float f2){
     return f1.equals(f2);
 }

 public static void main(String[] args) {
     float f1 = +0.0f;
     float f2 = -0.0f;
  
     System.out.println("f1 is equals to f2 : "+ (f1==f2));//prints true
        System.out.println("f1 is equals to

f2 : "+ isEqual(f1,f2));//prints false
    }

}

3. DataType1 - Datatype4 are all the same.

package com.twister;
public class Mystery {

 public static boolean isEqual(Object f1, Object f2){
     return f1.equals(f2);
 }

 public static void main(String[] args) {
     Object f1 = new Object()
     { 
         @Override
         public boolean equals(Object obj) {
             return false;
         }
     };
     Object f2 = f1;

     System.out.println("f1 is equals to f2 : "+ (f1==f2));//prints true
        System.out.println("f1 is equals to

f2 : "+ isEqual(f1,f2));//prints false
    }
}