698798
| Question | Answer |
| Object-Oriented Programming | Software dvpmt technology conceptualised as a group of objects working together |
| Bytecode | Format Java prgms are transformed into - can be run by any computer with a JVM |
| Platform neutrality | A program's ability to run w/o modif in different computing enviroinment |
| Java Virtual Machine (JVM) | Device installed on a computer to run Java bytecode |
| Procedural Programming | Programs are made of a series of instructions carried out in a sequence - tailored to a computer's manner of doing things |
| Object | A self-contained element of a prgm representing a specific group of features & designed to accomplish specific tasks |
| Class | Template used to create an object - objects created from the same class have similar features |
| CLASS = ? model OBJECT = ? | Class = ABSTRACT model for a CONCRETE object |
| Instantiation | Process of creating an object (instance) from a class |
| Attributes of a class | The data that differentiates one object from another; are used to describe/define objects from that class |
| Attributes are defined by ? | VARIABLES |
| Variables | Places to store information in a computer prgm |
| Instance variables or Object variables | Attributes that have values that differ from one object to another; define an attribute of a particular object |
| Class variable | Attribute of an entire class and all of its instances - only one value is stored no matter how many objects created |
| Behaviour of a class | The things that a class of objects can do to themselves and other objects, implemented by methods |
| Methods (~functions or subroutines in other prgming languages) | Group of related statements in a class that perform a specific task (on their own or other objects) // Perform ONE task if well-designed |
| Instance methods used when? | Used when working with an individual object of the class |
| Class methods apply to? | Apply to a class ITSELF |
| a String object | A group of letters, nbrs, punctuation, and other characters |
| an int | a numeric integer value |
| a float | a floating-point number |
| Inheritance | Mechanism that enables one class to inherit all the behaviour and attributes of another class, new class must only define how it is different from existing class |
| Subclass | A class inheriting from another class - all the attributes and behaviour of their superclass |
| Superclass | The class that gives inheritance |
| Top of the Java Class Hierarchy | The class Object |
| The class Object | The most general class in the hierarchy - all classes inherit from this superclass |
| Subclassing | Mechanism for creating new classes as the differences between those classes and their superclass |
| Default superclass | Class Object |
| Overriding | Preventing a superclass' method from being used by creating one in the subclass w/ same name, return type, & arguments // the 1st method def found going bottom up is used |
| SINGLE inheritance | Each Java class can have ONLY ONE superclass (but multiple subclasses) |
| Interface | A collection of methods indicating a class has some behaviour in addition to what it inherits from its superclass - methods are not defining behaviour in interface, needs to be done in the class |
| Package | A way to group related classes & interfaces |
| Default package | java.lang |
| \n | new line |
| Statement | Simple command causing something to happen |
| Expression | Statement producing a value |
| Return value | Value produced by a statement |
| Block (block statement) | A group of statements |
| Variable | Place where info can be stored while a prgm is running, and that can be changed at any point |
| 3 kinds of variables | Instance Class Local |
| Local variables | Used inside method def, or even smaller blocks w/n a method - cease to exist afterwards |
| Equals sign "=" | To assign a value to a variable |
| Byte | 8 bits -128 - 127 |
| short | 16 bits -32,768 -32,767 |
| int | 32 bits +/-2x10^9 |
| long | 64 bits +/- 9 x 10^12 |
| Floating-point numbers | Numbers w/ a decimal point |
| Float | 1.4E-45 to 3.4E38 |
| Double | Even more precise than float |
| System.out.print()/println() | method called to display strings and other info to the output device - takes a single argument ("string") or several, ("string" + variable) |
| difference btw print() & println() | print() does not finish line with a \n character |
| Single line comment | //comment |
| multi line comment | /*comment *commen */!!!!!!!!!! |
| Javadoc comment | Official documentation on how class and methods work, /** ... */ |
| Literals | Any nbr, text, or other info directly representing a value |
| type long | Any integer literal larger than an int can hold (but L after said literal to indicate its long type) |
| Octal numbering | prepend with a 0 |
| Hexadecimal numbering | Ox... |
| Binary numbering | 0b..; |
| Type of floating-point literals | All double |
| exponents | e or EE ex: double x = 12e22 |
| Underscore in integer literals | Make it more readable: int jackpot = 3500000 int jackpot = 3_500_000 |
| Concatenate | Link two things |
| "new" op | to create a new object of class type, class name follows new |
| a constructor | special way to create a new instance of a class: it initialises the new obj and its variables, creates any other objs this obj needs, and performs any other op needed to initialise the obj |
| Dot notation | Form of addressing in which an instance or class variable has 2 pts: - A ref to an obj or class (L side) - A variable (R side) |
| Reference | An address that indicates where an object's variables and methods are stored |
| Casting | Process used to convert a value from one type to another |
| Object wrapper | Class used instead of primitive data type (ex: Integer, Double) |
| parseInt() | Class method of the Integer class o convert a String to a numeric type |
| autoboxing | automatically converting a primitive type to an object |
| unboxing | automatically converting an object to a primitive type |
| Arrays | A way to store a list of items w/ same primitive type, class, or common parent class - items are indexed |
| Array variable | It indicates the object or data type that the array will hold and the array's name |
| Scope of a variable | Part if the java prgm where the variable exists and can be used |
| a conditional statement | Executed only if a specific condition is met |
| Ternary (trois) or conditional operator | Alternative to if and else kwords that can return a value instead of executing a statement |
| For loop | Repeat a statement until a condition is met |
| Declarative languages | What but not necessarily how it should be don |
| Imperative languages | Specify both what and how to do something |
| Changing the size of an Array | 1) Create a new bigger array 2) Copy the elements across 3) Delete the old array $$$ |
| Creating an array | 1) float farray[] = new float[21] or 2) float[] farray = new float[21] Needs to specify size & type |
| Function prototype in Java | (return type) function(type arg1, type {…body…} ex: int myfun(int a, int b) {…} |
| Void procedure | A procedure simply manipulating some internal state, and thus not returning anything |
| Modularity | BREAK BIG PROBLEMS IN Each class represents a sub-uni of code that can be developed, tested, and updated independently from the rest of the code |
| Encapsulation (Information/Implementation Hiding) | A class should expose a clean interface that allows full interaction with it, but should expose nothing about its internal state (every field should be private by default) HELP minZe coupling and maxZe cohesion |
| Coupling | Refers to how much one class depends on another |
| High coupling is.. | BAD because it means changing one class will require us to fix up lots of others |
| Cohesion | Qualitative measure of how strongly related everything in the class is |
| Access Modifiers | Set access levels for classes, variables, methods, and constructors |
| Advantages of Immutability | - Easier to construct, test, and use - Can be used in concurrent contexts (can be shared between threads w/o worrying about contention issues) - Allows lazy instantiation |
| How do you "create" immutability in Java? | - Make all states private - Make state final (which tells the compiler the value never changes once constructed) - Remove setters methods: no methods should try to change any internal state |
| Advantages of static methods | - Easier to debug as only depends on static fields - self documenting - compiler can produce more efficient code since no specific object is involved |
| This (keyword) | Provides a reference to the current object, can only be used in a class method |
| super (kword) | Gives access to the direct parent (one step up the inheritance tree) |
| Static polymorphism | When we refer to an object via a parent type and both types implement a particular method, we do not know which method to run DEFAULT: run the parent method |
| Early-binding | When we decide at compile-time how to resolve our static polymorphism issue |
Want to create your own Flashcards for free with GoConqr? Learn more.