How do I copy an object in Java?

Question

Consider the code below:

DummyBean dum = new DummyBean();
dum.setDummy(\"foo\");
System.out.println(dum.getDummy()); // prints \'foo\'

DummyBean dumtwo = du         


        

Answer 1

This works too. Assuming model

class UserAccount{
   public int id;
   public String name;
}

First add compile 'com.google.code.gson:gson:2.8.1' to your app>gradle & sync. Then

Gson gson = new Gson();
updateUser = gson.fromJson(gson.toJson(mUser),UserAccount.class);

You can exclude using a field by using transient keyword after access modifier.

Note: This is bad practice. Also don't recommend to use Cloneable or JavaSerialization It's slow and broken. Write copy constructor for best performance ref.

Something like

class UserAccount{
        public int id;
        public String name;
        //empty constructor
        public UserAccount(){}
        //parameterize constructor
        public UserAccount(int id, String name) {
            this.id = id;
            this.name = name;
        }

        //copy constructor
        public UserAccount(UserAccount in){
            this(in.id,in.name);
        }
    }

Test stats of 90000 iteration:
Line UserAccount clone = gson.fromJson(gson.toJson(aO), UserAccount.class); takes 808ms

Line UserAccount clone = new UserAccount(aO); takes less than 1ms

Conclusion: Use gson if your boss is crazy and you prefer speed. Use second copy constructor if you prefer quality.

You can also use copy constructor code generator plugin in Android Studio.