If clone() value is made zero the original object value also changes to zero

Question

I am making a copy of my object by using clone() method. But when there is modification in the copy the original object is also modified. I have tried to replicate my issue in the following example. Here are 2 classes ClassA and ClassB.

public class ClassB implements Cloneable
{
    int num = 0;

    byte[] bit = new byte[1];

     //Getters and setters have been removed due to space constraint

            public Object clone() 
    {
        try
        {   
          ClassB obj = (ClassB)super.clone();

          obj.setNum(this.num);
               obj.setBit(this.bit);

          return obj;
        } catch (CloneNotSupportedException e) {
                return null;              }
    }
}

//Here is ClassA whioch contains the main method and uses clone

public class ClassA {

    public void cloneMethod(){

        ClassB objB = new ClassB();
        objB.bit[0] = (byte)0x8;
        objB.setNum(5);     

        ClassB objCopy = null;
        objCopy = (ClassB) objB.clone();

        if(objCopy.bit[0] != (byte)0x0)
        {
            objCopy.bit[0] = 0;
        }

        System.out.println(objB.bit[0]); //At this point the original object    value is also modified.

    }

    public static void main(String args[])
    {
        ClassA a = new ClassA();
        a.cloneMethod();
    }

}

Now how to retain the original object value? I know clone has certain disadvantages. I have tried with new key word also but it doesnt help.Please suggest. in my original code I have to use the original object bit value later for some more calculation and the copy object bit value will be 0. Thanks.

Answer 1

Don't set bit to the same byte[] as the original object, instead clone it as well:

obj.bit = this.bit.clone();

Also, you don't need to set num, because that will already be set correctly on the object returned by super.clone().