How to start new activity on button click

Question

In an Android application, how do you start a new activity (GUI) when a button in another activity is clicked, and how do you pass data between these two activities?

Answer 1

From the sending Activity try the following code

   //EXTRA_MESSAGE is our key and it's value is 'packagename.MESSAGE'
    public static final String EXTRA_MESSAGE = "packageName.MESSAGE";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
       ....

        //Here we declare our send button
        Button sendButton = (Button) findViewById(R.id.send_button);
        sendButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                //declare our intent object which takes two parameters, the context and the new activity name

                // the name of the receiving activity is declared in the Intent Constructor
                Intent intent = new Intent(getApplicationContext(), NameOfReceivingActivity.class);

                String sendMessage = "hello world"
                //put the text inside the intent and send it to another Activity
                intent.putExtra(EXTRA_MESSAGE, sendMessage);
                //start the activity
                startActivity(intent);

            }

From the receiving Activity try the following code:

   protected void onCreate(Bundle savedInstanceState) {
 //use the getIntent()method to receive the data from another activity
 Intent intent = getIntent();

//extract the string, with the getStringExtra method
String message = intent.getStringExtra(NewActivityName.EXTRA_MESSAGE);

Then just add the following code to the AndroidManifest.xml file

  android:name="packagename.NameOfTheReceivingActivity"
  android:label="Title of the Activity"
  android:parentActivityName="packagename.NameOfSendingActivity"