[JAVA] Introduction to Android application development

A memorandum of Android application development

Benefits of app development

--Learn Java and Kotlin ――You can make your own favorite app --Opening the way to professionals

release

Release from Google Play Console

** Notes, working method ** Note that if the package name is com.example, it cannot be released. If you want to change it, refactor and rename it from Android manifest.

Increase the version of build.gradle (app).

The size (resolution) of the icon can be changed by painting (for Windows).

The app name after installation is decided by Android Manifest.

AndroidManifest.xml


android:label="@string/app_name"

Source code control

In the case of Git Sourcetree for the time being

** How to clone ** The save destination path should be an empty folder and the name should be the same as the empty folder.

** Create local repository ** Open a terminal (button near the top right) and run git init in the directory you want to be the repository Press the + button and add with Add a repository

AndroidStudio If the device is no longer recognized after upgrading Andoid Studio, revoke the permission for USB debugging of the device.

Android Studio shortcut

ctrl + shift + enter Colon auto-completion

About the library

Pay attention to the version when using the library. If there is no version, a compile error or Gradle error may occur. Do I have to match the SDK version?

Example) implementation 'com.squareup.okhttp3:okhttp:3.10.0' implementation 'com.android.support:design:28.0.0' This is used as a set.

Source code (Android)

LayoutInflater (inflater) Load the resource (xml) and make it a view.

Tablayout pageTitle is final

Source code (Java)

public Make the specified class name and file name the same.

ArrayList Does it matter the size?

cast Substituting double for an int will truncate after the decimal point.

this.s Instance variable s

** Inheritance ** When a subclass is created, the parent class's constructor is executed before the child class's constructor is executed.

** Object class ** Implicit parent class of toString and getClass methods.

** Abstract class ** It is convenient to hold it as a variable (array OK), create an instance of the subclass, and assign it.

** Abstract method ** Because of the call abstraction?

interface By casting and assigning an instance in the interface, only the functions described in the interface can be used.

If the interface is static, it can be used as it is.

There is a way to implements and implement it in the class, and a way to implement it in a new (it looks like it is actually an anonymous class) and an anonymous class.

throws throws is used as a set with the method, and when an exception occurs, it returns to the method caller and catches.

Create your own exception handling class and catch it using throw (mark of exception occurrence).

equals equals returns boolean by comparing the same references.

protected It can be accessed from an instance of a subclass. (Not accessible from superclass instances)

** Anonymous class ** Since it is defined in the main routine, it is not processed in order from the top.

** Method ** By looking at the return value first, you can see what to do. Example) getView returns the view at the end.

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