** Data Types,Variables and Arrays**
Java strongly typed language:
- Every variable has a type and every expression has a type and every type is strictly is defined.
- All assignments in parameters or explicit passing through methods are checked for type compatibility.
- Java type checks all expressions and parameters to ensure all types are compatible.
Primitive types:(simple types)
- Java has eight types of primitive data as int,long,byte,short,char,float,double, and boolean.
Integer:
- Unsigned integer are not needed in java.
- The concept of unsigned was mostly specifies the high order bit.
- It manages the high order bit separately by unsigned right shift operator.
Byte:
- The smallest bit type is signed 8 it range from -128 to 127.
Short:
- It signed 16 bit type and range from -32768 to 32767
- Its the probably least used data type
Int:
- Its the most commonly used method type.It has signed 32 bit type
- It varies from -2147483648 to 214783647
- It commonly used to control loops and to index arrays.
Long:
- It signed 64 bit type is used where int type is not large to hold the desired value.
- It acts upto an great extent of data is needed.
- If you need a great value as a result you can use long integer(64 bit type)
Floating point types:(real numbers)
- It used when evaluating expressions that require fractional precise.
- It divides into float and double
Float:
- It has decimal points
In integer it has no decimal points.
single precision value that use 32 bits of storage
single precision is faster as compared to double precision in some computers.
Double:
- Double precision are denoted by double keyword and use 64 bits to store a value.
- Double precision is faster than single precision on some modern processor that optimized on mathematical calculations.
Characters:
- char is used to store the data type of character
- char in java is not the same as char in C and C++.
- Java char is 16 bit type.
- It is used to hold uni code characters and it also hold or read the integer type to perform arithmetic operations.
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Booleans:
- Java has a primitive type for logical values.(return the value of booleans in primitive type)
- It have two possible values True or False.
Operator uses < as boolean value.
println() display output by boolean values.
Literals:
- Provide a means of expressing a specific values in a program.
- Syntactic representation of boolean,character,numeric,string.
Floating point literals:
- Decimal values with a fractional component is called floating point.(17.596)
Integer literals:
- Any whole number value is an integer literal(1,2,40).
Boolean literal:
- Literal is a numeric value without a decimal point as 65,-89.
Type Conversion and Casting:
The two kinds of conversion are implicit(cast and convert) and explicit(datatypes)
The value of one type is changed into value of another type without any special derivative from the programmer.
Casting incompatible types:
- Automatic type conversions are not fullfil the needs.In some cases narrowing conversions are values are made narrower and fit into target type.
- A cast is simply an explicit type conversion
- Automatic type promotion and type promotion rules.
Example:
{
return height*width*depth;
}
vol= mybox1.volume();
- In these statement vol stores the value of mybox1.volume executed values.
- void setdim{
}
- In these setdim sets the dimensions of the each box.