Java对象的深拷贝和克隆

在有的时候,我们希望对Java对象执行“深拷贝”。

在Java中,没有提供类似的C++的拷贝构造函数,但是提供了默认的”克隆”接口 Clonable。

如果我们要对一个只包含基础类型(int / long /String)的对象进行克隆,只需要实现Clonable并实现clone()函数即可。

如下:

	public class Row implements Cloneable {

		long id;
		String data;

		@Override
		public Row clone() throws CloneNotSupportedException {
			return (Row) super.clone();
		}
	}

如果要克隆一个引用了其他对象的Object,就要复杂一些了。

public class Employee implements Cloneable{
 
private int empoyeeId;
private String employeeName;
private Department department;
 
public Employee(int id, String name, Department dept)
{
this.empoyeeId = id;
this.employeeName = name;
this.department = dept;
}

//Modified clone() method in Employee class
@Override
protected Employee clone() throws CloneNotSupportedException {
    Employee cloned = (Employee)super.clone();
    cloned.setDepartment((Department)cloned.getDepartment().clone());
    return cloned;
}

//Accessor/mutators methods will go there
}

实际上,还可以通过序列化/反序列化、ApacheCommons的SerializationUtils进行深度拷贝。

参考文献:A guide to object cloning in java

 

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