Adding text messaging to my Android app?

Sure thing! That's a great alternative to a button and is definitely possible! Using a TextWatcher hasn't been taught in the Android courses here but, I'd be happy to guide you through it.

I'm going to use a send button on the EditTextActivity however, you can always swap this out to whatever you want.

First of all, we have two options.

• Use send button
• Don't use send button

If you are using the send button, we're in luck because we already have a send button in our recipients.xml file. Now, if we're using this button in both EditTextActivity and RecipientsActivity then maybe this isn't such a great name. We can perform a refactor by Right-clicking on recipients.xml and choosing Refactor >> Rename and then give it something like sendMenu.

If you're not using the send button, create a new file called editText.xml and copy the same code from recipients.xml, changing the image icon.

Next, in EditTextActivity, you want to add this method and member variable:

protected MenuItem mSendMenuItem;

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.recipients, menu);
        mSendMenuItem = menu.getItem(0);
        return true;
    }

This will inflate our objects onto the menu (Only the send button which we won't see as we set it to be hidden), set mSendMenuItem to the item at index 0 (Again, the send button) and then return true to say that this has completed.

This is where the magic happens! We're now going to create a TextWatcher to detect if the text has changed and, if it has, show our icon! Let's update our onCreate() method in EditTextActivity to do that:

    // Add this member variable:
    protected EditText mEditText;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // misc code - setContentView() and super methods.

        // Copy from here \/

        mEditText = (EditText) findViewById(R.id.editText);

        mEditText.addTextChangedListener(new TextWatcher() {
            @Override
            public void beforeTextChanged(CharSequence s, int start, int count, int after) {
                // Intentionally blank
            }
            @Override
            public void onTextChanged(CharSequence s, int start, int before, int count) {
                // Intentionally blank
            }

            @Override
            public void afterTextChanged(Editable s) {
                if (s.length() > 0) {
                    mSendMenuItem.setVisible(true);
                }
                else {
                    mSendMenuItem.setVisible(false);
                }
            }
        });

    // To here /\

    }

Note: Replace the inner of the onCreate() method. Don't just replace your whole onCreate() method with this as, it doesn't include the misc code. I've provided comments of what bit should be copied.

Here, what we're doing is we're defining and initializing our EditText and then creating a TextWatcher listener that detects when our text has changed and whether its total length is greater than 0 (We have text).

This is foolproof and means a user can also backspace their text, causing the icon to then disappear again.

Now, in my previous post, I also talked about how you could limit the size of the message, just so that people aren't stupid and send a really long spammy message.

We could do this here with:

if (s.length > 0 && s.length < 20000) {

which would mean that the send icon only appears if the length is greater than 0 yet less than 20000. This works and, there is also another option (That's the beauty of programming - there's more than one way to do things).

We could also check once the button was pressed - so, in onOptionsItemSelected(), we could make it so that the user would only be brought to RecipientsActivity if the length is less than 20000 (Or any value you choose). This would mean that the user would be shown the button but, we should then prompt them that their message was too long and couldn't be sent. If we didn't show them a prompt, they could think that our app was broken!

I would usually recommend a better option here but, there isn't really one. I mean, we are checking if the length is less than 20000 every time a new character is entered but, even if we got rid of that, we're still checking if the length is greater than 0 every time. Therefore, there would probably be no noticeable performance difference between either option but, in the future, you should take these things into account and only run code where necessary, especially as we're developing for mobile devices with batteries.

Hopefully this should explain everything for you but, as always if there's anything else, give me a shout :)

Hello Harry James

can you please upload the code for send text feature in order to use it in ribbit app ?

regards