Book Image

Android Studio 3.5 Development Essentials - Java Edition

By : Neil Smyth
Book Image

Android Studio 3.5 Development Essentials - Java Edition

By: Neil Smyth

Overview of this book

Android applications have become an important part of our daily lives and lots of effort goes into developing an Android application. This book will help you to build you own Android applications using Java. Android Studio 3.5 Development Essentials – Java Edition first teaches you to install Android development and test environment on different operating systems. Next, you will create an Android app and a virtual device in Android Studio, and install an Android application on emulator. You will test apps on physical Android devices, then study Android Studio code editor and constraint layout, Android architecture, the anatomy of an Android app, and Android activity state changes. The book then covers advanced topics such as views and widgets implementation, multi-window support integration, and biometric authentication, and finally, you will learn to upload your app to Google Play console and handle the build process with Gradle. By the end of this book, you will have gained enough knowledge to develop powerful Android applications using Java.
Table of Contents (86 chapters)
86
Index

23.5 Configuring the Constraint Set

In the absence of any constraints, the ConstraintLayout view has placed the Button view in the top left corner of the display. In order to instruct the layout view to place the button in a different location, in this case centered both horizontally and vertically, it will be necessary to create a ConstraintSet instance, initialize it with the appropriate settings and apply it to the parent layout.

For this example, the button needs to be configured so that the width and height are constrained to the size of the text it is displaying and the view centered within the parent layout. Edit the onCreate() method once more to make these changes:

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import androidx.constraintlayout.widget.ConstraintSet;

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private void configureLayout() {

    Button myButton = new Button(this);

    myButton.setText(getString(R.string.press_me));

    myButton.setBackgroundColor(Color...