Definitions Flashcards
Define Byte Code
The optimized instruction created by Java compiler from a java class. Carries a .class extension. Is sent to interpretation for native machine.
Define JVM
Is a java system software that converts byte code to machine code depending upon the machine.
Define JIT
Interprets the whole java byte code in one go to machine code. Makes the interpretation step faster. Interprets only the required byte code.
Define Garbage Collector
Background memory management tool that handles clearing memory space by java program so that user does not have to.
Define fundamental datatypes
supplied by language developers to define value storage, can’t store multiple values.
Define derived data types
store multiple values. eg arrays
Define User defined data types
combination of fundamental data types to store different types of data
Define method overloading
Method name is same; but signature is different
Define method overriding
Method name is same; but method body is different
What is class loader sub system or Java ClassLoader
Part of java run time environment that loads class dynamically into JVM.
Duplicate methods
Have same return type, and same signature.
Need not have same body.
Wrapper class
classes that can wrap objects around primitive data types
Constructor
special method that is automatically called for object creation by JVM. can be used to initialize member methods.
Default Constructor
A constructor that has empty parameters.
Also known as system constructor.
Is provided by default to all classes in JVM.
Object Parameterized Constructor
Copy Constructor.
Takes object of same type as parameter, copies corresponding values into new object.
Overloaded/Parameterized Constructor
same name as constructor name, and different signature(no. of para/type of para/order of para – at least one is different)
javap
command to list class profile(name, attributes, methods, and constructors). To be used only after compilation of a program.
Factory Method
a method that has same return type as class to which it belongs.
Define Inheritance
the process of deriving data members and methods from one class into another
base class
the class giving its members/methods to another class in inheritance also known as super/parent class.
derived class
the class taking members/methods from another class in inheritance also known as child/sub class
StackOverFlowError
when a method is called indefinitely, it fills up the stack memory, and causes this error.
Polymorphism
one things takes on many different forms
what does BLC stand for?
Business Logic Class
static binding
type of polymorphism that happens during compile-time. the method to be resolved is decided at compile-time.
dynamic binding
type of polymorphism that happens during runtime. the method to be executed can be resolved only during runtime when objects are known to JVM.
abstract concrete class
a class that has only null body methods; it needs the abstract keyword.
null block method
a method that is defined but has no statements.
interface in java
collection of universal common reusable data members, and methods | collection of public static final data members and public abstract methods.
functional interface
an interface having only one abstract method which is implemented in an anonymous inner class
API
Application Programming Interface; collection of packages.
package
collection of other packages, classes, and sub packages
Access modifiers
show sharing privileges; applied to classes and interfaces
Access specifiers
show sharing privileges; applied to data members and data methods
Exception
a run time error that occurs in java program
checked exceptions
direct subclasses of java.lang.Exception these are caught by the compiler at compile time itself even before they get into runtime;
example: FileNotFound, Interrupted, IOException, ClassNotFound
un-checked exceptions
direct subclasses of java.lang.RuntimeException these are caught only at runtime
technical definition of exception
An object that is created at runtime, and has the error message.
if a common method has “throws” keyword, it is called
common exception methods
define a thread
a flow of control in a program is called a thread.
Define FGT
Foreground Thread: a thread that executes programmers java logic.
Define BGT
Background Thread: a thread that monitors the execution of foreground threads.
Define address space
Temporary space created in memory for execution of method
Define mutators and inspectors
same as setter and getter methods.
