Equal assignment operator
When we use assignment operator to assign one object to
another a new object does not get created. Both the objects point to same
reference. Only reference gets copied. Changes in any object will change the
object reference and will be reflected for the other one. Comparison using (==)
operator will return TRUE since both points to same reference. Needless to
mention equal() also returns TRUE.
Default hashCode() of super class will return same result
for both.
package com.deva;
public class Student implements Cloneable {
private int age;
private String name;
private String dept;
public String getDept() {
return dept;
}
public void setDept(String
dept) {
this.dept = dept;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public String getName() {
return name;
}
public void setName(String
name) {
this.name = name;
}
public static void main(String[]
args) throws CloneNotSupportedException {
Student student =new Student();
student.age=25;
student.name="deva";
student.dept="CS";
Student student2 = student;
student2.age = 35;
System.out.println("Student1
detail "+student);
System.out.println("Student2
detail "+student2);
System.out.println("Student1
hashcode="+student.hashCode());
System.out.println("Student2 hashcode="+student2.hashCode());
System.out.println("== operator
returns "+(student==student2));
System.out.println("equals
method returns "+(student.equals(student2)));
}
@Override
public String toString() {
String s = "Age="+this.age+" Name="+this.name+" Dept="+this.dept;
return s;
}
}
|
O/P:-
Student1 detail Age=35 Name=deva
Dept=CS
Student2 detail Age=35 Name=deva
Dept=CS
Student1 hashcode=1523239031
Student2 hashcode=1523239031
Student2 hashcode=1523239031
== operator returns true
equals method returns true
Creation of Object using clone()
In case when we create an object using clone() method a separate
object gets created with a different reference but with same properties.
Changes to one object will not be reflected for other one since both the object
has different reference. Comparison using (==) operator will return FALSE.
Default equals() method of parent class will also return
FALSE and hashCode() of super class will return different result for both.
package com.deva;
public class Student implements Cloneable {
private int age;
private String name;
private String dept;
public String getDept() {
return dept;
}
public void setDept(String
dept) {
this.dept = dept;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public String getName() {
return name;
}
public void setName(String
name) {
this.name = name;
}
public static void main(String[]
args) throws CloneNotSupportedException {
Student student =new Student();
student.age=25;
student.name="deva";
student.dept="CS";
Student student2 = (Student)
student.clone();
student2.age = 35;
System.out.println("Student1
detail "+student);
System.out.println("Student2
detail "+student2);
System.out.println("Student1
hashcode="+student.hashCode());
System.out.println("Student2 hashcode="+student2.hashCode());
System.out.println("== operator
returns "+(student==student2));
System.out.println("equals
method returns "+(student.equals(student2)));
}
@Override
public String toString() {
String s = "Age="+this.age+" Name="+this.name+" Dept="+this.dept;
return s;
}
}
|
O/P:-
Student1 detail Age=25 Name=deva
Dept=CS
Student2 detail Age=35 Name=deva
Dept=CS
Student1 hashcode=925838130
Student2 hashcode=2042428395
== operator returns false
equals method returns false
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