Java
Vars:
Names prefixed by letter, underscore, dollarsign
Primitive = basic var
- boolean (true/false)
- char: unsigned 16 bits
- byte: signed 8 bits
- short: signed 16 bits
- int: signed 32 bits
- long: signed 64bits
- float: 32 bits
- double: 64 bits
When assiging a constant float value to var assign as:
v = 32.5f to cast constant as a float as Java asumes double
Complex:
- String
- String title;
- title = "xxx";
- Arrays (are objects as well)
- int[] nums // declares num are an array of ints (as a type)
- nums = new int[7] // creates the new array
- int[] nums = new int[7] // combine both the above
Uninitialised vars
Local (as opposed to instance) vars must be initialised or you get a compiler error
Reference = link to an object
- like a pointer so you are passing the address of the object around not the object
- eg: dog myDog = new Dog();
Objects
Uninitialised vars
Instance vars always have a default value:
- integers: 0
- float: 0.0
- boolean: false
- references: null
Methods
void bark(intNoOfBarks) {
xxxx;
}
A method uses parameters, a caller passes arguments
Methods can return values
int bark(intNoOfBarks) {
xxxx;
return xxx;
}
Getters /Setters (Acessors/Mutators)
Mark all instance vars privaye and associated geters/seters public