Keyword

Description

abstract

A non-access modifier. Used for classes and methods: An abstract class cannot be used to create objects (to access it, it must be inherited from another class). An abstract method can only be used in an abstract class, and it does not have a body. The body is provided by the subclass (inherited from)

assert

For debugging

boolean

A data type that can only store true or false values

break

Breaks out of a loop or a switch block

byte

A data type that can store whole numbers from -128 and 127

case

Marks a block of code in switch statements

catch

Catches exceptions generated by try statements

char

A data type that is used to store a single character

class

Defines a class

continue

Continues to the next iteration of a loop

const

Defines a constant. Not in use - use final instead

default

Specifies the default block of code in a switch statement

do

Used together with while to create a do-while loop

double

A data type that can store whole numbers from 1.7e−308 to 1.7e+308

else

Used in conditional statements

enum

Declares an enumerated (unchangeable) type

exports

Exports a package with a module. New in Java 9

extends

Extends a class (indicates that a class is inherited from another class)

final

A non-access modifier used for classes, attributes and methods, which makes them non-changeable (impossible to inherit or override)

finally

Used with exceptions, a block of code that will be executed no matter if there is an exception or not

float

A data type that can store whole numbers from 3.4e−038 to 3.4e+038

for

Create a for loop

goto

Not in use, and has no function

if

Makes a conditional statement

implements

Implements an interface

import

Used to import a package, class or interface

instanceof

Checks whether an object is an instance of a specific class or an interface

int

A data type that can store whole numbers from -2147483648 to 2147483647

interface

Used to declare a special type of class that only contains abstract methods

long

A data type that can store whole numbers from -9223372036854775808 to 9223372036854775808

module

Declares a module. New in Java 9

native

Specifies that a method is not implemented in the same Java source file (but in another language)

new

Creates new objects

package

Declares a package

private

An access modifier used for attributes, methods and constructors, making them only accessible within the declared class

protected

An access modifier used for attributes, methods and constructors, making them accessible in the same package and subclasses

public

An access modifier used for classes, attributes, methods and constructors, making them accessible by any other class

requires

Specifies required libraries inside a module. New in Java 9

return

Finished the execution of a method, and can be used to return a value from a method

short

A data type that can store whole numbers from -32768 to 32767

static

A non-access modifier used for methods and attributes. Static methods/attributes can be accessed without creating an object of a class

strictfp

Restrict the precision and rounding of floating point calculations

super

Refers to superclass (parent) objects

switch

Selects one of many code blocks to be executed

synchronized

A non-access modifier, which specifies that methods can only be accessed by one thread at a time

this

Refers to the current object in a method or constructor

throw

Creates a custom error

throws

Indicates what exceptions may be thrown by a method

transient

A non-accesss modifier, which specifies that an attribute is not part of an object's persistent state

try

Creates a try...catch statement

var

Declares a variable. New in Java 10

void

Specifies that a method should not have a return value

volatile

Indicates that an attribute is not cached thread-locally, and is always read from the "main memory"

while

Creates a while loop