问题描述
我有一个THIS类,该类显然对我创建的每个实例都是可变的,但是我想知道是否存在
某种包装器(或某种包装器)使该类的一个特定对象不可变。例如Collections.unmodifiableList(beanList)
。
class Animal {
private String name;
private String commentary;
public Animal(String nombre,String comentario) {
this.name = nombre;
this.commentary = comentario;
}
@Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
Animal animal = (Animal) o;
return Objects.equals(name,animal.name);
}
@Override
public int hashCode() {
return Objects.hash(name);
}
public String getName() {
return name;
}
public String getCommentary() {
return commentary;
}
public void setCommentary(String commentary) {
this.commentary = commentary;
}
public void setName(String name) {
this.name = name;
}
}
解决方法
我知道的唯一方法是实例化它,并覆盖能够修改特定实例的方法:
Animal animal = new Animal("name","commentary") {
@Override
public void setCommentary(String commentary) {
throw new UnsupportedOperationException("The Animal is immutable");
}
@Override
public void setName(String name) {
throw new UnsupportedOperationException("The Animal is immutable");
}
};
这也满足了仅该类的一个特定实例具有特殊行为的条件。
如果您需要更多它们,请创建一个包装类,将其充当装饰器(并非完全如此)。 别忘了,将类设为final
,否则您将可以按照我上面描述的方式覆盖其方法,并且其不变性可能会破坏。
Animal animal = new ImmutableAnimal(new Animal("name","commentary"));
final class ImmutableAnimal extends Animal {
public ImmutableAnimal(Animal animal) {
super(animal.getName(),animal.getCommentary());
}
@Override
public void setCommentary(String commentary) {
throw new UnsupportedOperationException("The Animal is immutable");
}
@Override
public void setName(String name) {
throw new UnsupportedOperationException("The Animal is immutable");
}
}