Intent Extras To Send Data Between Activities

GetUserData.java

// This is the code showing how to get user input from and EditText

// First, use findViewById to get the EditText view (just like you would
// get any other view in the layout
EditText myEditText = (EditText) findViewById(R.id.send_edit_text);

// Then from the edit text, perform two actions, first to get the "Text", then
// to change it to a String. It is kind of silly that you can't just have one
// action "getString", but it is the way that the engineers of Android chose
// to make it so ¯\_(ツ)_/¯
String userInput = myEditText.getText().toString();

MainActivity.java

// This code create an Intent. An intent is like an envelope. This specifies where
// the envelope is going.
// You have seen this code before when just opening a new activity
Intent intent = new Intent(this, OtherActivity.class);

// This adds some extra data to the intent. Using the envelope analogy
// this is like putting something (a letter, a card) into the envelope
// for the recieving activity

// The key will always be a String - it is like the "Name"
// of the Extra that you give. In this example the key is "KeyExample"
// The value can be pretty much any primitive value, or a set of strings
// In this example the value is "ValueExample"
// You will use the key on the other side to get the value.
intent.putExtra("KeyExample", "ValueExample");

// This code you have seen before. It starts the new activity.
startActivity(intent);

OtherActivity.java

// Get the intent that caused this activity to start. In the mailing analogy
// this is like picking up for mail.
Intent startingIntent = getIntent();

// Get the String Extra from the intent using the key "KeyExample"
// Remember, when we sent the intent message, we put one Extra
// value, and it's key was spelled exactly "KeyExample". This will retrieve
// that value from the intent. In the analogy, this is like opening
// the envelope to receive the letter.

// Notice also how the method we call is getStringExtra. This is because
// the value being sent it a String.
String sentData = startingIntent.getStringExtra("KeyExample");

// This sets the text view to show the data that was sent. It will show the
// text "ValueExample" in this example
informationTextView.setText("The value sent is " + sentData);

// In this example, we want to output the value for the user to see.
// To do that, we first get the textview we are going to ouput the value in.
// You've seen this before.
TextView informationTextView = (TextView) findViewById(R.id.information_text_view);