'What is setContentView(R.layout.main)?

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 in advance!

android layout

Solution 1:^[1]

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.

Solution 2:^[2]

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.

Solution 3:^[3]

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.

Solution 4:^[4]

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).

Solution 5:^[5]

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.

Solution 6:^[6]

in order to explain the method setContentView(:int) which takes a layout file as a parameter.

so let's imagine i want to create a view and add to it a button :

so in android , the setContentView will only takes an xml file (layout) and inflate it to an empty activity.

at the end to add my customized view which contains a button to the empty activity i will only use the same method setContentView(v).

Sources

This article follows the attribution requirements of Stack Overflow and is licensed under CC BY-SA 3.0.

Source: Stack Overflow

Solution	Source
Solution 1	vwvw
Solution 2
Solution 3
Solution 4	Babavali Sheik
Solution 5	ColdFire
Solution 6	Anouar Bakouch

'What is setContentView(R.layout.main)?

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