英文:
How to deep copy a List<Object>
问题
我有一个对象，这个对象还包括其他对象，像这样
学生：
public class Student implements Cloneable {
public int id;
public String name;
public List<Integer> score;
public Address address;
......
@Override
protected Object clone() throws CloneNotSupportedException {
return super.clone();
}
}
地址：
public class Address implements Serializable, Cloneable {
public String type;
public String value;
......
@Override
protected Object clone() throws CloneNotSupportedException {
return super.clone();
}
}
现在我有一个 List<Student> studentsList，如何进行深层复制？如果在地址中有其他对象，我该如何复制 studentsList？
英文:
I have an object and this object also includes other objects, like this
Student :
public class Student implements Cloneable {
public int id;
public String name;
public List<Integer> score;
public Address address;
......
@Override
protected Object clone() throws CloneNotSupportedException {
return super.clone();
}
}
Address :
public class Address implements Serializable,Cloneable{
public String type;
public String value;
......
@Override
protected Object clone() throws CloneNotSupportedException {
return super.clone();
}
}
Now i have a List\<Student> studentsList How can I deep copy studentsList？How can I copy studentsList if there are other objects in Address?
答案1
得分: 4
你需要实现一个正确的 clone() 方法，类似于以下的代码：
public class Student implements Cloneable {
public int id;
public String name;
public List<Integer> score;
public Address address;
// ......
@Override
protected Object clone() throws CloneNotSupportedException {
Student std = new Student();
std.id = this.id; // 不可变
std.name = this.name; // 不可变
std.score = this.score.stream().collect(Collectors.toList()); // Integer 是不可变的
std.address = (Address) this.address.clone();
return std;
}
}
英文:
You need to implement a correct clone() method like
public class Student implements Cloneable {
public int id;
public String name;
public List<Integer> score;
public Address address;
......
@Override
protected Object clone() throws CloneNotSupportedException {
Student std = new Student();
std.id = this.id; // Immutable
std.name = this.name; // Immutable
std.score = this.score.stream().collect(Collectors.toList()); // Integer is immutable
std.address = (Adress) this.address.clone();
return std;
}
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