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Java Coding Samples
https://www.cs.utexas.edu/~scottm/cs307/codingSamples.htm
https://www.programiz.com/java-programming/examples
https://futurecreator.github.io/2017/01/27/java-variable-data-type/
https://www.tutorialspoint.com/java/java_basic_operators.htm
****** Java Install (ÀÚ¹Ù ¼³Ä¡) and Path
https://www.oracle.com/technetwork/java/javase/downloads/index.html
=======================================Path=======================================================
Goto Control panel
Á¦¾îÆÇ \ ½Ã½ºÅÛ ¹× º¸¾È \ ½Ã½ºÅÛ \ °í±Þ½Ã½ºÅÛ¼³Á¤ \ ȯ°æº¯¼ö \PATH >ÆíÁý >¼¼¹ÌÄÝ·Ð(;)ºÙÀÎ ÈÄ COPY C:\Program Files\Java\jdk1.8.0_192\bin
/*** COPY C:\Program Files\Java\jdk1.8.0_192\bin **********/
Á¦¾îÆÇ\½Ã½ºÅÛ ¹× º¸¾È\½Ã½ºÅÛ
°í±Þ½Ã½ºÅÛ¼³Á¤ > ȯ°æº¯¼ö > PATH >ÆíÁý >¼¼¹ÌÄÝ·Ð(;)ºÙÀÎ ÈÄ COPY C:\Program Files\Java\jdk1.8.0_192\bin
-> ;C:\Program Files\Java\jdk1.8.0_192\bin
====================================================================================================================
Á¤¼ö ÀÚ·áÇü
ÀÚ·áÇü ¸Þ¸ð¸®Å©±â Ç¥Çö °¡´É ¹üÀ§
byte 1 Byte -128 ~ 127 (-2ÀÇ 7½Â ~ 2ÀÇ 7½Â-1)
short 2 Byte -32768 ~ 32767 (-2ÀÇ 15½Â ~ 2ÀÇ 15½Â-1)
int 4 Byte -2147483648 ~ 2147483647 (¾à 21¾ï) (-2ÀÇ 31½Â ~ 2ÀÇ 31½Â-1)
long 8 Byte -922337036854775808 ~ 9223372036854775807 (-2ÀÇ 63½Â ~ 2ÀÇ 63½Â-1)
///////////////////////////////////////////////////////////////////
** byte Over Flow
class IntTest
{
public static void main(String[] args)
{
byte n = 127;
n = (byte)(n+1); // Over Flow
System.out.println(n);
}
}
Result : -128
** byte Under Flow
class IntTest
{
public static void main(String[] args)
{
byte n = -128;
n = (byte)(n-1); // Under Flow
System.out.println(n);
}
}
Result : 127
==================================================================================
The Bitwise Operators ---- https://www.tutorialspoint.com/java/java_basic_operators.htm
<< (left shift) Binary Left Shift Operator. << 1 : *2¿Í µ¿ÀÏ
>> (right shift)Binary Right Shift Operator. >> 1 : /2¿Í µ¿ÀÏ
>>> (zero fill right shift) >>> ¹«Á¶°Ç ¾ç¼ö¸¸µå´Â ¿ªÇÒ
-------------------------------------------------------------------------------------
º¯¼öÀ§Ä¡ ¹Ù²Ù±â(ºñÆ®¿¬»êÀÚÀÌ¿ë) ----- using bit operator
class Test07
{
public static void main(String[] args)
{
int a=7;
int b=5;
System.out.println("a: "+a);
System.out.println("b: "+b);
a=a^b;
b=b^a;
a=a^b;
System.out.println("a: "+a);
System.out.println("b: "+b);
}
}
===============================================================
½Ç¼ö ÀÚ·áÇü
ÀÚ·áÇü ¸Þ¸ð¸® Å©±â bit ±¸¼º
float 4 Byte ºÎÈ£(1bit) + Áö¼ö(8bit) + °¡¼ö(23bit) = 32 bit = 4 Byte (1.40239846E-45f ~ 3.40282347E+38f)
double 8 Byte ºÎÈ£(1bit) + Áö¼ö(11bit) + °¡¼ö(52bit) = 64 bit = 8 Byte (4.94065645841246544E-324 ~ 1.79769313486231570E+308)
¹®ÀÚ ÀÚ·áÇü
ÀÚ·áÇü ¸Þ¸ð¸® Å©±â Ç¥Çö ¹üÀ§
char 2 Byte \u0000 ~ \uFFFF
1 char c = 'A';
2 System.out.println(c); // A
3 System.out.println((int) c); // 65
Âü °ÅÁþ ÀÚ·áÇü
Âü/ °ÅÁþ ÀÚ·áÇüÀº true ¿Í false µÎ°¡Áö °ªÀ» °¡Áö°í ÁÖ·Î Á¶°Ç¹®¿¡¼ È°¿ëµË´Ï´Ù.
1 boolean isChecked = false;
2 if (isChecked()) {
3 // do something..
4 } else {
5 // ...
6 }
====================================================================================================================
********Java Exe (ÀÚ¹Ù ½ÇÇà)
Basic Form (±âº»Çü½Ä)
class ClassName (Ŭ¶ó½º¸í(ÆÄÀϸí°ú ÀÌÄ¡½ÃŲ´Ù))
{
public static void main(String[] args)
{
System.out.println("Hello Java"); ===============>Print command
}
}
cmd ¿ÀÇÂ
½ÇÇà Æú´õ·Î À̵¿
javac ÆÄÀϸí.java
java ÆÄÀϸí
=====================Java Programming
--------------- Java Input Sample
import java.util.Scanner;
class Scannerinfo{
public static void main(String[] args){
Scanner sc = new Scanner(System.in);
String name;
int age;
System.out.println("Please Type Name");
name = sc.next();
System.out.println("Type Age");
age=sc.nextInt();
System.out.println("Your Name is "+name);
System.out.println("And Your age is "+age);
}
}
Result :
Please Type Name
PILSOOK
Type Age
28
Your Name is PILSOOK
And Your age is 28
--------------- Java char,for and if Sample
import java.util.Scanner;
class charTest1
{
public static void main(String[] args)
{
String str;
int cnt=0;
Scanner sc = new Scanner(System.in);
System.out.println("Type String ====> ");
str = sc.next();
for (int i=0;i < str.length() ;i=i+1 )
{
char a = str.charAt(i);
if(a > 65 && a < 90)
cnt += 1;
}
System.out.println(cnt);
}
}
result:
Type String ====>
HelloWOrld
3
---------------
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