????????????????????????false????????????????????????????????????employee????????????????????????true??

????????????????????????дequals??????

    public boolean equals(Object o) { 
            if(o == null) 
            { 
                return false; 
            } 
            if (o == this) 
            { 
               return true; 
            } 
            if (getClass() != o.getClass()) 
            { 
                return false; 
            } 
            Employee e = (Employee) o; 
            return (this.getId() == e.getId()); 
    }

???????????????????????????EauqlsTest???????true??

????So are we done????У?????????????????????????

    import java.util.HashSet; 
    import java.util.Set; 
    
    public class EqualsTest 
    { 
        public static void main(String[] args) 
        { 
            Employee e1 = new Employee(); 
            Employee e2 = new Employee(); 
    
            e1.setId(100); 
            e2.setId(100); 
    
            //Prints 'true' 
            System.out.println(e1.equals(e2)); 
    
            Set<Employee> employees = new HashSet<Employee>(); 
            employees.add(e1); 
            employees.add(e2); 
            //Prints two objects 
            System.out.println(employees); 
        }

??????????????????????????????????employee????equals????true??Set???????洢???????????????????????

??????????????????????????hashCode()????JDK??Javadoc?????????????????дequals()???????????дhashCode()??????????????????????????????????????

    @Override
     public int hashCode() 
     { 
        final int PRIME = 31; 
        int result = 1; 
        result = PRIME * result + getId(); 
        return result; 
     }