Flashcards in Comp Sci Ch. 2 Deck (60)
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What is an object?
Part of a java program that represents a real object
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What is an attribute?
An objects values that represent its state
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What is a method?
A group of programming statements given a name so we can use them when we need them
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What is a class?
The data-type/blueprint of an object. Represents a concept
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What is encapsulation?
The means by which an object protects and manages its own info
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What is inheritance?
The means by which a class can be created by other classss
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What is polymorphism?
The idea by which we we can refer to objects if different but related types in the same way
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What do we directly interact with in programs?
Objects
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Can there be multiple objects in a class?
Yes
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What do methods do?
The functions of the program
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This is when one class can be used to derive other classes
Inheritance
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What is object and method in system.out.println ("hello world") ?
System.out is object. Println is method. Hello world is parameter
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Where does the info we feed into a method considered?
Parameter
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What is abstraction?
Hiding details
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How do we know if something is abstract?
We don't need to think about the inner workings
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What is a character string in java?
An object
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What can you not do with a literal string?
Break it across two lines
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What is contametation?
Splicing together multiple strings
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What does a concatenator do?
String together numbers and letters working left to right
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What do you use parentheses for in a concatenator?
To add stuff
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What is an escape sequence?
A series of character that represent a special character
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What is a variable a name for?
A location in memory
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How do you declare a variable?
Specify it's name and the info it will hold
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What changes the value of a variable?
An assignment statement
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What must you specify when using a variable?
The variable type
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What just you make sure you don't do when reassigning a variable?
Not put a data type again
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What does putting final before a data type do?
Make it a constant
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What are the data types for intergers?
Byte, short, int, and long
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What are the data types for numbers with decimals?
Float and double
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What is the data type for characters?
Char
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What is the Boolean data type?
Boolean
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What are booleans good
For?
True and false statements
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What is a trade off of double?
It only allows 15 sig figs
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What does % mean in java?
Remainder
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What does the char function use?
Unicode
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Why is the assignment operater a low precedence?
Cause the right side is finished then a value is assigned
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What is a widening conversion?
Going from a data type with less bits to more bits
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What is a bad data type conversion?
Int to double
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What are 3 types of conversions?
Assignment, arithmetic promotion, and casing
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What is assignment conversion?
Assigning an Internet variable to a double variable
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What is arithmetic promotion?
Dividing a double and an interger to get another double?
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What is casting?
Doing something and specifying the output data type
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What are enumerated values?
Values outside of a class and the main method
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What happens when we say to string something?
Memory is allocated for it
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What is the process of creating an object?
Instantiation
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Are strings powerful?
Yes
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What do strings have on their own?
Their own class
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What do index numbers start at?
0
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What are strings?
Objects that you can use methods on, so they have special functionalities
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How are interferes and doubles made into objects?
Wrapper class
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What is autoboxing?
Converting a primitive data type into an object
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What is a class library?
A collection of classes that contain methods
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What is the java standard class library?
Additional functionalities that come with java
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What classes are included in the java standard class library?
System and string
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What is a package?
A collection of classes, methods, and more that can be shared with others
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What do you do to use classes not readily in java?
Import them
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What does a * mean?
The wild card-import all classes in a package
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What is the scanner class?
A part of java.util that let's us get input from the user
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What do applets not have?
A main method
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