概述
java.lang.Object#clone
By convention, the returned object should be obtained by calling {@code super.clone}.
If a class and all of its superclasses (except {@code Object}) obey this convention, it will be the case that {@code x.clone().getClass() == x.getClass()}.
按照约定，应该通过调用super.clone来获得新的克隆对象；
The method {@code clone} for class {@code Object} performs a specific cloning operation.
First, if the class of this object does not implement the interface {@code Cloneable}, then a {@code CloneNotSupportedException} is thrown.
Note that all arrays are considered to implement the interface {@code Cloneable} and that the return type of the {@code clone} method of an array type {@code T[]} is {@code T[]} where T is any reference or primitive type.
Otherwise, this method creates a new instance of the class of this object and initializes all its fields with exactly the contents of the corresponding fields of this object, as if by assignment; the contents of the fields are not themselves cloned.
Thus, this method performs a "shallow copy" of this object, not a "deep copy" operation.
clone方法 执行clone操作；
如果 被克隆的对象没有实现Cloneable，将会抛出CloneNotSupportedException；
注意：所有的数组 都被认为实现了Cloneable；
clone方法仅创建一个新的对象，对象的字段内容并没有clone；
clone方法是 浅拷贝，不是深拷贝；
The class {@code Object} does not itself implement the interface {@code Cloneable}, so calling the {@code clone} method on an object whose class is {@code Object} will result in throwing an exception at run time.
Object类 自身没有实现Cloneable，所以调用Object类的对象的clone将会抛出异常；
深拷贝&浅拷贝
浅拷贝
public static void main(String[] args) throws CloneNotSupportedException {
List<String> list = Arrays.asList("a", "b");
Person person = new Person("test", list);
Object clone = person.clone();
System.out.println(person == clone);
int[] arr = {1,3,4};
int[] clone1 = arr.clone();
System.out.println(arr == clone1);
}
static class Person implements Cloneable{
private String name;
private List<String> list;
Person(String name, List<String> list){
this.name = name;
this.list = list;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public static void test(){
System.out.println("test...");
}
public List<String> getList() {
return list;
}
public void setList(List<String> list) {
this.list = list;
}
@Override
protected Object clone() throws CloneNotSupportedException {
return super.clone();
}
}
深拷贝
Person的clone方法深拷贝实现
@Override
protected Object clone() throws CloneNotSupportedException {
Person clone = (Person) super.clone();
ArrayList<String> list = new ArrayList<>(this.list);
clone.setList(list);
return clone;
}
