Data Types in Java
By: Abinaya
The Java programming language is strongly-typed, which means that all variables must first be declared before they can be used. This involves stating the variable's type and name, as you've already seen:Doing so tells your program that a field named "gear" exists, holds numerical data, and has an initial value of "1". A variable's data type determines the values it may contain, plus the operations that may be performed on it. In addition toint gear = 1;
int
, the Java programming
language supports seven other primitive data types. A primitive type is
predefined by the language and is named by a reserved keyword. Primitive
values do not share state with other primitive values. The eight primitive
data types supported by the Java programming language are:
- byte: The
byte
data type is an 8-bit signed two's complement integer. It has a minimum value of -128 and a maximum value of 127 (inclusive). Thebyte
data type can be useful for saving memory in large arrays, where the memory savings actually matters. They can also be used in place ofint
where their limits help to clarify your code; the fact that a variable's range is limited can serve as a form of documentation. - short: The
short
data type is a 16-bit signed two's complement integer. It has a minimum value of -32,768 and a maximum value of 32,767 (inclusive). As withbyte
, the same guidelines apply: you can use ashort
to save memory in large arrays, in situations where the memory savings actually matters. - 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, uselong
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 byint
. - float: The
float
data type is a single-precision 32-bit IEEE 754 floating point. Its range of values is beyond the scope of this discussion. As with the recommendations forbyte
andshort
, use afloat
(instead ofdouble
) if you need to save memory in large arrays of floating point numbers. This data type should never be used for precise values, such as currency. For that, you will need to use the java.math.BigDecimal class instead. Numbers and Strings coversBigDecimal
and other useful classes provided by the Java platform. - double: The
double
data type is a double-precision 64-bit IEEE 754 floating point. Its range of values is beyond the scope of this discussion. For decimal values, this data type is generally the default choice. As mentioned above, this data type should never be used for precise values, such as currency. - boolean: The
boolean
data type has only two possible values:true
andfalse
. Use this data type for simple flags that track true/false conditions. This data type represents one bit of information, but its "size" isn't something that's precisely defined. - char: The
char
data type is a single 16-bit Unicode character. It has a minimum value of'\u0000'
(or 0) and a maximum value of'\uffff'
(or 65,535 inclusive).
String
object; for example, String s =
"this is a string";
. String
objects are immutable,
which means that once created, their values cannot be changed. The String
class is not technically a primitive data type, but considering the special
support given to it by the language, you'll probably tend to think of it as
such. Archived Comments
1. we need to know how to write this coding..
name:ADIB
ID :2008221234
View Tutorial By: lalala at 2009-07-15 20:35:16
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