[JAVA] various(변수) 예제

package dayday02;
public class test02 {
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		int radius = 5; //init + declaration
		double area = radius * radius * 3.14;
		System.out.println("반지름이 5인 원의 넓이 : " + area);
		
		//various ? 
		//a small memory can have a data
		//various declaration : makes a various
		// form : various name ;
		
		
		radius = 10; //store a data 
		
		// = store a data when its a following value
		int n1 = 1;
		int n2 = 2;
		//n1 = n2;
		n2 = n1;
		
		System.out.println("n1 : " + n1);
		System.out.println("n2 : " + n2);
		
		System.out.println(radius * radius * 3.14);
		System.out.println(area);
		
		//caution : 
		//1. it can't be use when not declaration
		// ex> n3 =100; .. -> int n3 = 100;
		
		//2. it cant be calculate and print when not init
		// ex> int n4;, int n5 = n4 + 10; n4 has a garage data
		
		//3. 1 various = 1 data
		
		//4. they use always same various form
		double d1; d1 = 3.14; //d1 = "ABC";
		int n5; n5 = 1; n1 = (int)1.0;    //casting calculator (int)
		
		byte b1 = 1; //1byte integer
		
		String str = "a" + 10;
		System.out.println(str);
		
		
	}
}