[SOLVED] Passing data through Intents

Passing data through Intents

I always get a java.lang.NullPointerException when retrieve the data from my MainActivity to my second Activity.

This from my MainActivity:

Intent i = new Intent(MainActivity.this,ScanActivity.class);
i.putExtra("isConnected", String.valueOf(isConnected));
i.putExtra("serverIP", serverIP);
startActivity(i);

And here's where I get the NullPointerException:

Intent extras = getIntent();
public String isConnected = extras.getStringExtra("isConnected");
public String serverIP = extras.getStringExtra("serverIP");

Is my code wrong or is there something else that causes it to be null?

Solution

You cannot get Intent until SecondActivity is instantiated. It's the reason for NPE. Move the code inside of the SecondActivity's onCreate() method body.

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.your_layout);

    Intent extras = getIntent();
    String isConnected = extras.getStringExtra("isConnected");
    String serverIP = extras.getStringExtra("serverIP");
}