class HelloWorld {
public static void main(String[] args) {
System.out.println("Hello World!");
}
}
> javac HelloWorld.java
> java HelloWorld
Hello World!
Manifest-Version: 1.0
Main-Class: HelloWorld
> jar cvfm HelloWorld.jar manifest.mf HelloWorld.class
> java -jar HelloWorld.jar
Hello World!
型 | サイズ | 初期値 | 範囲 |
---|---|---|---|
byte | 8bit | 0 | -128 ~ 127 |
short | 16bit | 0 | -32768 ~ 32767 |
int | 32bit | 0 | -2147483648 ~ 2147483647 |
long | 64bit | 0 | -9223372036854775808 ~ 9223372036854775807 |
float | 32bit | 0.0F | ±3.40E38 ~ ±1.40E-45 |
double | 64bit | 0.0D | ±1.79E+308 ~ ±4.94E-324 |
char | 16bit | '\u0000' | 2byte の文字コード |
boolean | 1bit | false | true または false |
//String str ⇒ int n
int n = Integer.parseInt(str, 10);
//int n ⇒ String str
String str = Integer.toString(n);
//float f ⇒ int n
int n = (int)f;
java -Djava.util.logging.config.file=/path/to/logging.properties MainClass
# logging.properties
handlers = java.util.logging.ConsoleHandler, java.util.logging.FileHandler
.level = ALL
java.util.logging.ConsoleHandler.level = INFO
java.util.logging.ConsoleHandler.formatter = java.util.logging.SimpleFormatter
java.util.logging.FileHandler.level = WARNING
java.util.logging.FileHandler.formatter = java.util.logging.SimpleFormatter
java.util.logging.FileHandler.encoding = UTF-8
java.util.logging.FileHandler.append = false
# %t - temp
# %h - home
# %g - generation
# %u - unique
java.util.logging.FileHandler.pattern = log/%u_%g.log
java.util.logging.FileHandler.count = 7
#java.util.logging.FileHandler.filter =
#java.util.logging.FileHandler.limit = 102400
/*
<applet code="AppletSample.class" width="200" height="50"></applet>
*/
import java.applet.Applet;
import java.awt.Graphics;
public class AppletSample extends Applet {
public void paint(Graphics g) {
g.drawString("Hello, World", 70, 30);
}
}
> javac AppletSample.java
> appletviewer AppletSample.java
<html>
<head>
<title>AppletSample</title>
</head>
<body>
<applet code="AppletSample.class" width="200" height="50"></applet>
</body>
</html>
/** */
コメント内にjavadocタグを付けて記入。HTMLタグも使える。
javadoc -d doc DocSample.java