rrmo rrmo - 3 months ago 17
Java Question

How to implement hashCode and equals method

How should I implement

hashCode()
and
equals()
for the following class in Java?

class Emp
{
int empid ; // unique across all the departments
String name;
String dept_name ;
String code ; // unique for the department
}

Answer

in Eclipse right mouse click-> source -> generate hashCode() and equals() gives this:

/* (non-Javadoc)
 * @see java.lang.Object#hashCode()
 */
@Override
public int hashCode() {
    final int prime = 31;
    int result = 1;
    result = prime * result + (code == null ? 0 : code.hashCode());
    return result;
}
/* (non-Javadoc)
 * @see java.lang.Object#equals(java.lang.Object)
 */
@Override
public boolean equals(Object obj) {
    if (this == obj)
        return true;
    if (obj == null)
        return false;
    if (!(obj instanceof emp))
        return false;
    Emp other = (Emp) obj;
    return code == null ? other.code == null : code.equals(other.code);
}

I've selected code as a unique field

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