考虑下面的代码:
DummyBean dum = new DummyBean();
dum.setDummy("foo");
System.out.println(dum.getDummy()); // prints 'foo'
DummyBean dumtwo = dum;
System.out.println(dumtwo.getDummy()); // prints 'foo'
dum.setDummy("bar");
System.out.println(dumtwo.getDummy()); // prints 'bar' but it should print 'foo'
所以，我想把dumm复制到dum2，在不影响dum2的情况下改变dumm。但是上面的代码并没有这样做。当我改变了dumm中的一些东西，同样的变化也会发生在dum2中。
我想，当我说dumtwo = dum时，Java只复制了引用。那么，有没有办法创建一个新的dum副本并将其分配给dumtwo呢?
当前回答
请按照以下步骤进行:
public class Deletable implements Cloneable{
private String str;
public Deletable(){
}
public void setStr(String str){
this.str = str;
}
public void display(){
System.out.println("The String is "+str);
}
protected Object clone() throws CloneNotSupportedException {
return super.clone();
}
}
无论你想要得到另一个对象，简单地执行克隆。 例句:
Deletable del = new Deletable();
Deletable delTemp = (Deletable ) del.clone(); // this line will return you an independent
// object, the changes made to this object will
// not be reflected to other object
其他回答
你可以从http://x-stream.github.io/:用XStream自动深度复制
XStream是一个简单的库，用于将对象序列化为XML和反向 一次。
将其添加到项目中(如果使用maven)
<dependency>
<groupId>com.thoughtworks.xstream</groupId>
<artifactId>xstream</artifactId>
<version>1.3.1</version>
</dependency>
Then
DummyBean dum = new DummyBean();
dum.setDummy("foo");
DummyBean dumCopy = (DummyBean) XSTREAM.fromXML(XSTREAM.toXML(dum));
这样你就有了一个副本，而不需要实现任何克隆接口。
请按照以下步骤进行:
public class Deletable implements Cloneable{
private String str;
public Deletable(){
}
public void setStr(String str){
this.str = str;
}
public void display(){
System.out.println("The String is "+str);
}
protected Object clone() throws CloneNotSupportedException {
return super.clone();
}
}
无论你想要得到另一个对象，简单地执行克隆。 例句:
Deletable del = new Deletable();
Deletable delTemp = (Deletable ) del.clone(); // this line will return you an independent
// object, the changes made to this object will
// not be reflected to other object
深度克隆是您的答案，它需要实现Cloneable接口并重写clone()方法。
public class DummyBean implements Cloneable {
private String dummy;
public void setDummy(String dummy) {
this.dummy = dummy;
}
public String getDummy() {
return dummy;
}
@Override
public Object clone() throws CloneNotSupportedException {
DummyBean cloned = (DummyBean)super.clone();
cloned.setDummy(cloned.getDummy());
// the above is applicable in case of primitive member types like String
// however, in case of non primitive types
// cloned.setNonPrimitiveType(cloned.getNonPrimitiveType().clone());
return cloned;
}
}
你会这样称呼它 DummyBean dumtwo = dumm .clone();
在包中导入org.apache.commons.lang.SerializationUtils;有一种方法:
SerializationUtils.clone(Object);
例子:
this.myObjectCloned = SerializationUtils.clone(this.object);
传递你想要复制的对象并获取你想要的对象:
private Object copyObject(Object objSource) {
try {
ByteArrayOutputStream bos = new ByteArrayOutputStream();
ObjectOutputStream oos = new ObjectOutputStream(bos);
oos.writeObject(objSource);
oos.flush();
oos.close();
bos.close();
byte[] byteData = bos.toByteArray();
ByteArrayInputStream bais = new ByteArrayInputStream(byteData);
try {
objDest = new ObjectInputStream(bais).readObject();
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
} catch (IOException e) {
e.printStackTrace();
}
return objDest;
}
现在将objDest解析为所需的对象。
编码快乐!
