Clone() and object copys

I have been reading about String and arrays and trying to understand the difference between clone() and system.arraycopy..... Here are my questions regarding this:
1. Why isn't there a deep copy for String, especially if we all need to keep writing code to make up for it?
2. What happens when using the assignment operator for a non-array object, say String? Is it getting a reference, or new memory with a copy of the values? eg.
String strThis= "Hello Java";
String strNew = strThis;

I have been reading about String and arrays and trying
to understand the difference between clone() and
system.arraycopy..... Look at the arguments for each method and read the JavaDoc - clone creates an object, whereas arraycopy copies a subarray to an existing subarray.
Here are my questions regarding
this:
1. Why isn't there a deep copy for String, especially
if we all need to keep writing code to make up for
it?Sting objects are immutable, so what would you gain from a deep copy? What code do "we all need to keep writing to make up for it"?
2. What happens when using the assignment operator for
a non-array object, say String? Is it getting a
reference, or new memory with a copy of the values?
eg.
String strThis= "Hello Java";
String strNew = strThis;It gets a copy of the reference.

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hi,
Why clone() in Object Class is protected
Why finalize() in Object Class is protected
Waiting for your reply
suresh

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All,
I this the correct way to clone a object? if not so can anyone point me the right way to do that. Because this method is taking longer time to execute.
import java.io.*;
public class ObjectCloner
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calvino_ind wrote:
i might be wrong, but i think there are some really easier ways to clone an object:
public class Age {
int numberOfYears;
public Age(int numberOfYears) {
this.numberOfYears = numebrOfYears;
public Object clone() {
return new Age(this.numberOfYears);
No! This is very wrong. For this simple example, all one needs is class Age to implement Cloneable and
public Object clone() {
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}which will automatically give you a shallow clone of the the class.
Consider what ill happen with your approach when one clones superclasses of class Age.
Edited by: sabre150 on May 26, 2008 3:42 PM

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What is the need to clone an object
give me the scenarios where we use cloneable interface

In a very simple statements,
clone method will return the new object with the
SAME SOURCE STATE. Where as
creating an object using "new" will give completely
new object.According to whom? I was under the impression that the state of the object returned by calling close was not defined except from what is returned by the Object class.
As for clone being faster than constructors, it can be. It depends on what the constructor does. For instance, I'm sure its faster to clone an ArrayList than to create a new one by passing the old one into its constructor. Depends on the implementation of the constructor vs. the implementation of the clone.
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Thanks for your valuable help

According to the rule of cloning a object can be
cloned only if
it implements Cloneable interface ? In the following
example
class B extends class A which does not implement
Cloneable interface,class B does implement Cloneable
interface.
when I try to clone an object of class A in class B it
is very
allowing to be cloned which is a contradictary?Please
go through the
example and suggest what is wrong ?
class A
int v = 100;
public Object Clone()
return new A();
class B extends A implements Cloneable
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A b = null;
b = (A)a.clone();
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System.out.println("Value of v1 :" +b.v1);
Thanks for your valuable helpApart the fact that like that program cannot function, you didn't clone anything. You've just created another instance of class A!
Cloning means to create a copy of an existing object with aonother one having exact members (name, value, behaviour) like the first one!
Try to replace this piece of code:
A a = new A();
a.v = 500;
A b = null;
b = (A)a.clone();
System.out.println("Value of a.v :" +a.v);
System.out.println("Value of b.v :" +b.v);
and write "Clone" method like this: "clone". See that you'll obtain:
Value of a.v :500
Value of a.v :100
good luck!
m

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