For beginner of learning Java

1. Author LIU XUE
2023-01
Compare with other programming language

2. • 自己紹介（2分ほど）
• Java に関する紹介（10分）
• JDKの説明(5分)
• 開発ツールIDEの紹介（10分）
• 開発環境構築（20分）
• 実例ソース（10分）
• Javaの基本知識
• 基本タイプ
• パッケージ

3. • 出身
■Skillset :
.NET(vb.net,c#),
Java, go/golang, python
■working experience in fields:
Web technologies, security,
AWS clouding,
data science

4. A Java package is a group of classes that
are related by purpose or by application
import javax.swing.*;
import javax.swing.JFrame;
Swing package is used for graphical
desktop application

5. • JDK のインストール
• 環境変数 environment variable を設定

6. Type the “environment” in the search, open the
Edit the system environment form

7. JAVA_HOMEを作成する
Path値を設定する（binを指定してください）
Bin はインストールしたJavaのフォルダ

8. コマンド プロントで
Type java -version
Java のインストールを確認する

9. • Java Development Kit
• Official and commercial JDK form Oracle
• https://www.oracle.com/java/technologies/downloads/

11. • Eclipse
• IntelliJ IDEA

12. • Type the at the command line
java -version

13. A group of abstract methods defining some behavior
An interface defines a set of methods that a class must implement
interface Driveable {
boolean startEngine();
void stopEngine();
float accelerate( float acc );
boolean turn( Direction dir );
}

14. • Comment in Java コメント
• Java text and core utilities テキスト クラス
• Java collection
• Primitive type in Java(基本タイプ）
• Code structure in Java

15. • Git
• Github
• Subversion

22. Java コメント①
c-style block comment
/* This is a
multiline
comment. */
Shortcut for comment in Eclipse IDE

23. Java コメント②
c++ style line comment
// This is a single-line comment

24. Type Definition Approximate range or precision
boolean true or false
char 64K characters
byte 8-bit, signed -128 to 127
short
int
long
float
double

25. • if ( condition )
• statement;
• else
• statement;
If/else

26. • int value = 2;
• switch( value ) {
• case 1:
• System.out.println( 1 );
• case 2:
• System.out.println( 2 );
• case 3:
• System.out.println( 3 );
• }
• // prints 2, 3!
Switch①

27. int retValue = checkStatus();
switch ( retVal )
{
case MyClass.GOOD :
// something good
break;
case MyClass.BAD :
// something bad
break;
default :
// neither one
break;
}
An optional default case can be specified to catch unmatched conditions.
Switch②

28. consultant
Do/while

29. • Web 知識
• HTTP、protocols

30. • https://github.com/l0y/learnjava5e
• https://github.com/l0y/learnjava5e.git

32. •
• 継承 hierarchy
class Animal {
float weight;
...
void eat() {
...
}
...
}
class Mammal extends Animal {
// inherits weight
int heartRate;
...
// inherits eat()
void breathe() {
...
}
}

33. •
• Single catch
try {
readFromFile("foo");
...
}
catch ( Exception e ) {
// Handle error
System.out.println( "Exception while reading file: " + e );
...
}

34. •
• Multiple catch
try {
readFromFile("foo");
...
}
catch ( FileNotFoundException e ) {
// Handle file not found
...
}
catch ( IOException e ) {
// Handle read error
...
}
catch ( Exception e ) {
// Handle all other errors
...
}

35. •

36. •
• Gradle
• Maven