Java Concepts Chapter 2:Using Objects

Rules for identifiers:

-can be made up of letters, digits, and the underscore character; however, they cannot begin with a digit. -You cannot use symbols or spaces. -You cannot use reserved words like public -identifiers are case sensitive

awt stands for

Abstract Windowing Toolkit

A method name is overloaded if...

a class has more than one method with the same name (but different parameter types)

By convention, variable names should start with

a lowercase letter

method that does not change the state of its implicit parameter

accessor method

describes the location of the object

an object reference

Class names should start with

an uppercase letter

the assignment operator (=) is used to

change the value of a variable

What does the length method do?

counts the number of characters in a string ex. String greeting = "Hello, World!"; n = greeting.length(); (n is then set to 13)

What does the toUpperCase method do?

creates another string object that contains the characters of the original string, with lowercase letters converted into uppercase letters ex. String river = "Nile"; String bigriver= river.toUpperCase();

parameter of the method other than the object the method invokes and is enclosed in parentheses

explicit parameter ex. in dave.setJobTitle("Candlestick Maker"); "Candlestick Maker" is the explicit parameter (dave is the implicit parameter)

the double type denotes...

floating-point numbers that can have fractional parts

Name of a variable, method, or class

identifier

Object on which the method is invoked

implicit parameter ex. in System.out.println(greeting), System.out is the implicit parameter

a sequence of instructions that accesses the data of an object

method

A method whose purpose is to modify the state of an object

mutator method

store numbers

number variables

store references

object variables

entities in your program that you manipulate by calling methods

objects

a collection of classes with a related purpose

package

An input to a method

parameter

In Java, number types are

primitive types, not classes

A result that the method has computed for use by the code that called it

return value

Carries out a search and replace operation

the replace method

In Java to write numbers in exponential notation...

using the notation En, for example, 1.4E-4

When a method returns no value it is

void ex. public void println(String output)