how to add simple code to an android application

Question

I have some confusion regarding where you put regular java code in an android application.

I'm using the Eclipse SDK and by default when you create an application it makes a .java file with an OnCreate() method. Is this where I would put my code, inside this method?

Right now in my layout I have an imageButton, once this button is clicked I want to open a new WebView page that gets it's HTML code from the index.html file found in the assets folder. This is what I have so far...

    Button button = (Button)findViewById(R.id.imagebutton1);
    if(button.isPressed())
    {
        WebView webview = new WebView(null);
        setContentView(webview);
        try {
            InputStream fin = getAssets().open("index.html");
                byte[] buffer = new byte[fin.available()];
                fin.read(buffer);
                fin.close();
                webview.loadData(new String(buffer), "text/html", "UTF-8");
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

I have this block of code at the end of the onCreate() method right under the line:

setContentView(R.layout.main);

However, once I run the program it crashes and tells me that it failed to start. I'm assuming that it has to do with the fact that the code is in the onCreate. I know that its not where I'm supposed to put it, but I can't think of anywhere else the code should go. Am I supposed to make a new .java file and have a main method there? I'm currently taking classes for C++ and C# so this android thing is still new to me.

Answer 1

Have you done the tutorials ? If not I would start there to learn about the basics of creating and working with an Android Activity . Once you have worked your way through them, read the application fundamentals to understand the lifecycle more fully.

Answer 2

You shouldn't be calling setContentView more than once in onCreate. The WebView should be in your main.xml layout file or else launch a new Activity that's layout contains the WebView. And also to hand the onClick on the button you need to call setOnClickListener ().

Answer 3

Please see Handling UI Events .

Also, if your program crashes, it would be helpful if you provided error messages from logcat.