Difference between Mutable objects and Immutable objects [duplicate]
Any one please give the diff between Mutable objects and Immutable objects with example.
Solution 1:
Mutable objects have fields that can be changed, immutable objects have no fields that can be changed after the object is created.
A very simple immutable object is a object without any field. (For example a simple Comparator Implementation).
class Mutable{
private int value;
public Mutable(int value) {
this.value = value;
}
//getter and setter for value
}
class Immutable {
private final int value;
public Immutable(int value) {
this.value = value;
}
//only getter
}
Solution 2:
Mutable objects can have their fields changed after construction. Immutable objects cannot.
public class MutableClass {
private int value;
public MutableClass(int aValue) {
value = aValue;
}
public void setValue(int aValue) {
value = aValue;
}
public getValue() {
return value;
}
}
public class ImmutableClass {
private final int value;
// changed the constructor to say Immutable instead of mutable
public ImmutableClass (final int aValue) {
//The value is set. Now, and forever.
value = aValue;
}
public final getValue() {
return value;
}
}
Solution 3:
Immutable objects are simply objects whose state (the object's data) cannot change after construction. Examples of immutable objects from the JDK include String and Integer.
For example:(Point is mutable and string immutable)
Point myPoint = new Point( 0, 0 );
System.out.println( myPoint );
myPoint.setLocation( 1.0, 0.0 );
System.out.println( myPoint );
String myString = new String( "old String" );
System.out.println( myString );
myString.replaceAll( "old", "new" );
System.out.println( myString );
The output is:
java.awt.Point[0.0, 0.0]
java.awt.Point[1.0, 0.0]
old String
old String