What is setContentView(R.layout.main)?

Question

I understand that it has to do with the App layout, but when do I have to use it? I tried to look for a link that explained this method, but I couldn\'t find it. Thank you i

Answer 1

Set the activity content from a layout resource. The resource will be inflated, adding all top-level views to the activity.

• Activity is basically a empty window
• SetContentView is used to fill the window with the UI provided from layout file incase of setContentView(R.layout.somae_file).
• Here layoutfile is inflated to view and added to the Activity context(Window).

Answer 2

Why setContentView() in Android Had Been So Popular Till Now?

setContentView(int layoutid) - method of activity class. It shows layout on screen.

R.layout.main - is an integer number implemented in nested layout class of R.java class file.

At the run time device will pick up their layout based on the id given in setcontentview() method.

Answer 3

As per the documentation :

Set the activity content from a layout resource. The resource will be inflated, adding all top-level views to the activity.

Your Launcher activity in the manifest first gets called and it set the layout view as specified in respective java files setContentView(R.layout.main);. Now this activity uses setContentView(R.layout.main) to set xml layout to that activity which will actually render as the UI of your activity.

Answer 4

You can set content view (or design) of an activity. For example you can do it like this too :

public void onCreate(Bundle savedinstanceState) {
    super.onCreate(savedinstanceState);

    Button testButon = new Button(this);

    setContentView(testButon);   
}

Also watch this tutorial too.

Answer 5

public void onCreate(Bundle savedinstanceState) {
            super.onCreate(savedinstanceState);

            Button testButon = new Button(this);

            setContentView(testButon);

            show();

}

Answer 6

In Android the visual design is stored in XML files and each Activity is associated to a design.

setContentView(R.layout.main)

R means Resource

layout means design

main is the xml you have created under res->layout->main.xml

Whenever you want to change the current look of an Activity or when you move from one Activity to another, the new Activity must have a design to show. We call setContentView in onCreate with the desired design as argument.