Difference between Mutable objects and Immutable objects [duplicate]

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
}