IT Specialist- Java Certification

getMessage()

This method can be used to retrieve the error message from an exception object

InputMismatchException

In Scanner methods, if the token read doesn't match the expected data type then this exception is thrown.

IOException

A type of Run-time error or exception that can occur while performing certain Input or Output operations- usually when there is a problem with the file

getStackTrace

Returns an array of stack trace elements

primitive data types

pre-defined java information ( int, boolean, double, char, float, long, byte, etc.)

Wrapper class

Converts primitive data types into objects

"Try" block

Used around code being attempted

"Catch" block

Catches exceptions and displays their information

"Finally" block

Always executes; after try and catch blocks

Public

Can be accessed by any class in a block of code

Static

Allows for a method to be called without instantiating the class in which it resides

Protected

Data can be modified or accessed by classes that share the same package or any subclass

Private

only accessible if in same class.

@Override

A Java annotation used to indicate that a method is intended to override an inherited method. - redefining a parent class method in the child class

Byte

-128 to 128

Integer

32 bit; -2.1 billion to 2.1 billion

Long

64 bit whole number

Short

-32,768 to 32,768

isEmpty()

Checks whether its empty; returns true if value is null and false if full

static

MUST ALWAYS be included in main method

Array declarations

names the array and specifies the type of its elements. Ex) String[] name = new String[1];

Araylist

Objects are referenced by index inside parentheses (2)

.add()

Cannot be used by Arrays, must be converted to ArrayList to use

Float precision

Can only be precise to 6 or 7 digits; floats also tend to lose precision in calculations

Strings are:

immutable (cannot be changed)

parseDouble()

converts a string into a double

Nested branch

If statements inside of it statements

A .java file can only...

Have one public, non static class

Static belongs...

To a class, but doesn't belong to an instance of that class (it can be called without the instance of that class)

checked expression

Happen at compilation

Unchecked expressions

Happen at runtime

/**

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/*

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