java_varaiables.java

package first1.java;

public class java_varaiables {

	public static void main(String[] args) {
		//byte b=-129;
		//byte b=128;
		//range should between -128 to 127
		//short s=32768;
		//range for short is -32768 to 32767
		
		/*
		 * Multi line comment
		 *
		 */
		
		//TYPE PROMOTION AND TYPE CASTING
		byte b=10;
		byte c=10;
		
		int d=b*c;//the result of a arithmetic operation will give u a integer by default - type promotion has happened
		
		System.out.println(d);
		byte ee=(byte)d;
		System.out.println(ee);
		
		int value=257;
		byte e=(byte)value;
		System.out.println(e);
		
		byte x=100;
		int xint=x;//compatible - its like a bigger vessel taking a smaller vessel in it.
		
		double dd=23.456;
		int intdd=(int)dd;
		
		System.out.println(intdd);//this will also loose the precision
		
		//VALID IDENTIFIERS
		
		// variables are suppose to adhere with qualified names (valid identifiers)
		
		//int 2i; - Variable name cannot start with a number
		//int %i; - Variable name cannot start with a special character other than $ and _ .
		int _i;// valid identifier - _ is accepted
		int $i;// valid identifier - $ is accepted
		int money$_1;//valid identifier - can also be combination - number can be added in between or at the end.
		
		
		//IDENTIFIER DECLARATION AND INITIALIZATION
		//number types
		
		byte bnum=100;
		short snum=100;
		int num=100;
		long lnum=100;
		
		//floating
		float fnum=100.12f;
		double dnum=34.434;
		
		//character
		char cc='A';// character is of int type
		int ccint=cc;
		System.out.println("ASCII value of a...."+ccint);
		
		int myint=169;
		System.out.println((char)myint);
		
		boolean boo=true;//in java it wont accept 0 or 1
		
		String str="hello world";
		
		
		

	}

}