Question about primitive variable types in Java?

Question

I have a question about primitive variable types. How come whenever I declare a long variable, I have to put an "l" at the end of the value or else I get a compiler error saying "integer number too large."? It also happens with doubles, too.

And I have another question about "double" variable types. How come the Java documentation thing lists them as being able to hold values from "8 bytes IEEE 754. Covers a range from 4.94065645841246544e-324d to 1.79769313486231570e+308d (positive or negative)." But when I put in a higher value, even something (relatively) small like two billion won't fit unless I put a "d" at the end of the value. Why is this? And what does the "-324d" and "+308d" thing mean? Is this scientific notation or is that the decimal precision of the "double" variable type? Thanks.

bibsmack17 · Accepted Answer

The l and the d tell the compiler that it should treat the preceding value as a long integer or double floating point, respectively.

The +308 and -324 represent powers. The 'E' separates the significand (4.94065645841246544 in the first case) from the exponent.

angel04 · Answer

Java supplies four different primitive integer data types whose characteristics are
type  size
byte 8
short 16
int   32
long  64
Lets talk about int and long	

int: The int data type is a 32-bit signed two's complement integer. It has a minimum value of -2,147,483,648 and a maximum value of 2,147,483,647 (inclusive). For integral values, this data type is generally the default choice unless there is a reason (like the above) to choose something else. This data type will most likely be large enough for the numbers your program will use, but if you need a wider range of values, use long instead.

long: The long data type is a 64-bit signed two's complement integer. It has a minimum value of -9,223,372,036,854,775,808 and a maximum value of 9,223,372,036,854,775,807 (inclusive). Use this data type when you need a range of values wider than those provided by int.

int  size is 32 bit while Long size is 64 bit
to show the difference between int and long it is need to put 'L' at the end of long integer

Now if you use any ineger in your program  whose maximum value  is greater than  2,147,483,647. This means your ineger becomes now Long. to show your integer is Long you have to 
to put 'L'
if you don't use 'L' java compiler considered as int  and  
  give you error becausee size is passing it's limit of int and enters in Long so you have to put 'L'

	
0
	
-128
	
+127
short
	
16
	
0
	
-32768
	
+32767
int
	
32
	
0
	
-2147483648
	
+2147483647
long
	
64
	
size(bits)
	
default value
	
minimum value
	
maximum value

Question about primitive variable types in Java?

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