How to pass class variable between activities?

Question

I created a class Telnet and I inicialize it on the Mainactivity. Now I want to access the telnet I inicialized in the MainActivity in all other activities of the project. What I am doing is creating a get function:

public Telnet getMyTelnet() {
    return telnet;
}

And then just call it wherever I want. When I call it in fragments I do it like this:

MainActivity activity = (MainActivity) getActivity();
            telnet = activity.getMyTelnet();

The problem is when I need it in another activity. How can I do it? I tried this but no luck.

MainActivity a = new MainActivity ();
            telnet = a.getTelnet();

Answer 1

In android there are two ways to achieve send and receive objects bebtween Activities: they must:

• Serializable (Implment object as Serializable)
  or
• Parcelable (Implement object as Parcelable)

you will need to implement Parcelabel and add the following methods to the class

a constructor with a parcel as parameter

public Telnet(Parcel in) {
    readFromParcel(in);
}

override the writeToParcel method

 @Override
    public void writeToParcel(Parcel dest, int flags) {

        // write each field into the parcel. When we read from parcel, they
        // will come back in the same order
        dest.writeString(strVar); // to write your string variables
        dest.writeInt(intVar); // to write your int variables
    }

a method for read from Parcel

private void readFromParcel(Parcel in) {

    strVar= in.readString();
    intVar= in.readInt();
}

a parcel creator

public static final Parcelable.Creator CREATOR =
    new Parcelable.Creator() {
        public Telnet createFromParcel(Parcel in) {
            return new Telnet(in);
        }

        public Telnet[] newArray(int size) {
            return new Telnet[size];
        }
    };

@Override
    public int describeContents() {
        return 0;
    }

then your Telnet class is ready to be transfer to another activities.

Now use it: in the main act do:

Telnet obj = new Telnet();

// Set values etc.

Intent i = new Intent(this, MyActivity.class);
i.putExtra("your.package.Telnet", obj);

startActivity(i);

and in the second activity do:

@Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        Bundle b = getIntent().getExtras();
        Telnet obj =
            b.getParcelable("your.package.Telnet");
    }

Answer 2

create Telnet instance in MyActivity class as static. and right this method

punlic static Telnet telnet;

onCreate() {
 //initialise telnet
}

onResume() {
//initialise telnet if null;
}

onStop() {
//make telnet null
}
public static Telnet getTelnet() {
return telnet;

Let me know if it works or not