What is xmlns attribute in Android?

Xmlns means xml namespace. It is created to avoid naming conflicts in the xml’s. In order to avoid naming conflicts by any other way we need to provide each element with a prefix. Now android here simply means we are assigning the namespace “http://schemas.android.com/apk/res/android” to it.

What are the attributes in Android?

View Attributes

What is app showAsAction?

android:showAsAction Keyword. When and how this item should appear as an action item in the app bar. A menu item can appear as an action item only when the activity includes an app bar.

What does Match_parent mean in Android?

public static final int MATCH_PARENT. Special value for the height or width requested by a View. MATCH_PARENT means that the view wants to be as big as its parent, minus the parent’s padding, if any. Introduced in API Level 8.

What is difference between app and Android?

android is usually used for attribute coming from Android SDK itself. app is often used if you are using the support library. You may also see other namespaces if you are using custom views (of your own or form a library).

What is Tools targetApi?

tools:targetApi This tells the tools that you believe this element (and any children) will be used only on the specified API level or higher. This stops lint from warning you if that element or its attributes are not available on the API level you specify as your minSdkVersion .

Why is TextView used in Android?

TextView is the user interface which displays the text message on the screen to the user. It is based on the layout size, style, and color, etc. TextView is used to set and display the text according to our specifications.

What is the purpose of TextView?

A TextView displays text to the user and optionally allows them to edit it. A TextView is a complete text editor, however the basic class is configured to not allow editing.

What is the ActionBar Android?

The ActionBar, now known as the App Bar, is a consistent navigation element that is standard throughout modern Android applications. The ActionBar can consist of: An application icon. An “upward” navigation to logical parent. An application or activity-specific title.

What is Android checkableBehavior?

The android:checkableBehavior attribute accepts either: single. Only one item from the group can be checked (radio buttons) all. All items can be checked (checkboxes)

What is the difference between Wrap_content and Match_parent?

Conclusion : fill_parent and match_parent are the same, used when we want the height or width of a view to be as big as its parent view, fill_parent being deprecated. wrap_content is used when we want the view to occupy only as much space as required by it.

What is Match_parent and Wrap_content?

fill_parent, and match_parent are the same, used when we want the height or width of a view to being as big as its parent view, fill_parent being deprecated. wrap_content_with_button.png. wrap_content is used when we want the view to occupy only as much space as required by it.

What are tools attributes in Android Studio?

Tools attributes reference. Android Studio supports a variety of XML attributes in the tools namespace that enable design-time features (such as which layout to show in a fragment) or compile-time behaviors (such as which shrinking mode to apply to your XML resources).

What is the use of the include Attribute in a layout?

This attribute allows you to point to a layout that uses this layout as an include, so you can preview (and edit) this file as it appears while embedded in its parent layout. Now the layout preview shows this TextView layout as it appears inside the activity_main layout.

What is the @menu attribute used for?

This attribute specifies which menu the layout preview should show in the app bar. The value can be one or more menu IDs, separated by commas (without @menu/ or any such ID prefix and without the .xml extension). For example: These attributes set minimum and maximum values for a NumberPicker view.