MyApp.java -> Compile -> MyApp.class
Write once, run anywhere
ではjavaの基礎から行きます。
public class MyApp {
public static void main(String[] args){
System.out.println("Hello world");
}
}
[vagrant@localhost java]$ javac MyApp.java
[vagrant@localhost java]$ ls
AdminUser.class MyApp.class MyInteger.class User.class
AmericanUser.class MyApp.java MyRunnable.class com
JapaneseUser.class MyData.class Printable.class java1
MyApp$1.class MyException.class Result.class
[vagrant@localhost java]$ java MyApp
Hello world
変数
public class MyApp {
public static void main(String[] args){
// 変数
String msg;
msg = "hello world again";
System.out.println(msg);
}
}
public class MyApp {
public static void main(String[] args){
char a = 'a';
// 整数 byte short int long
int x = 10;
long y = 55555555L;
double d = 23423.344;
float f = 32.33F;
boolean flag = true; // flase
// \n, \t
String msg = "hello w\norld a\tgain";
System.out.println(msg);
}
}
[vagrant@localhost java]$ javac MyApp.java
[vagrant@localhost java]$ java MyApp
hello w
orld a gain
public static void main(String[] args){
int i;
i = 10 / 3;
System.out.println(i);
i = 10 % 3;
System.out.println(i);
int x = 5;
x++;
System.out.println(x);
}
[vagrant@localhost java]$ javac MyApp.java
[vagrant@localhost java]$ java MyApp
3
1
6
ほ～
