JAVA Quick Reference Cheat Sheet | Cheat Sheet Java Programming

JAVA Quick Reference

Author: Jialong He

Jialong_he@bigfoot.com

http://www.bigfoot.com/~jialong_he

Simple Data Types

byte 8 -128..127

short 16 -32,768..32,767

int 32 -2,147,483,648.. 2,147,483,647

long 64 -9,223,372,036,854,775,808..

9,223,372,036,854,775,807

float 32 3.4e-0.38.. 3.4e+0.38

double 64 1.7e-308.. 1.7e+308

char 16 Complete Unicode Character Set

Boolean true, false

decare a variable:

type identifier [= value];

Arrays

int array_name[ ];

array_name=new int[100 ]; declare an integer array and allocate

100 elements of memory.

int array_name[ ] = new int [

100];

int array_name [ ] = {1, 2, 3, 4};

declare and allocate an integer array in

one statement.

int array_name[] = new

int[10][20]; multidimensional array.

null for reference type (class, array).

Class

{public|final|abstract} class name

{ [class_variable_declarations]

public static void main{String[] args) {statements}

[methods]

}

this, super

Methods

{public | private } [static] {type | void} name (arg, ..., arg) {statements}

Variable

{public | private } [static] type name [= expression];

Arithmetic Operators

+, -, *, /

%, ++, -- addition, subtraction, multiplication, division

modulus, increment, decrement.

Relational Operators

==, !=, >, <,

>=, <= equal, not equal, greater, less,

greater or equal, less or equal.

Logical Operators

&, |, !, ^, ||, &&, AND, OR, NOT, XOR, short -circuit OR, AND

Bitwise Operators

&, |, ~, ^,

>>, >>>, << AND, OR, NOT, XOR

shift right, shift right zero fill, shift left.

Comments

// rest of line

/* multiline comment */

/** documentation comment */

Compile and Run

javac nameOfFile.java

java nameOfFile

CLASSPATH must set correctly.

The name of the file has to match exactly the name of the class.

Flow Control

if (Boolean-expression) statement1; [ else statement2; ]

while loop

[initialization]

while (termination-clause) {

body;

[iteration;]

}

do while loop

do {

body;

[iteration;]

} while (termination-clause);

for loop

for (initialization; termination-clause; iteration)

body;

Program Structure

class className {

public static void main (String args[ ]) {

statements;

}

method definition1

…

method definitionN

}

Key words

abstract boolean break byte byvalue

case cast catch char class

const continue default do double

else extends false final finally

float for future generic goto

if implements import inner instanceof

int interface long native new

null operator outer package private

protected public rest return short

static super switch synchronized this

throw throws transient true try

var void volatile while

Java packages

java.applet Provides the classes necessary to create an applet

and the classes an applet uses to communicate with

its applet context.

java.awt Contains all of the classes for creating user

interfaces and for painting graphics and images.

java.awt.color Provides classes for color spaces.

java.awt.datatransfe

r Provides interfaces and classes for transferring data

between and within applications.

java.awt.dnd Drag and Drop is a direct manipulation gesture

found in many Graphical User Interface systems

that provides a mechanism to transfer information

between two entities logically associated with

presentation elements in the GUI.

java.awt.event Provides interfaces and classes for dealing with

different types of events fired by AWT

components.

java.awt.font Provides classes and interface relating to fonts.

java.awt.geom Provides the Java 2D classes for defining and

performing operations on objects related to two-

dimensional geometry.

java.awt.im

Provides classes and interfaces for the input method

framework.

java.awt.im.spi Provides interfaces that enable the development of

input methods that can be used with any Java

runtime environment.

java.awt.image Provides classes for creating and modifying

images.

java.awt.image.rend

erable Provides classes and interfaces for producing

rendering-independent images.

java.awt.print Provides classes and interfaces for a general

printing API.

java.beans Contains classes related to developing beans --

components based on the JavaBeansTM architecture.

JAVA Quick Reference Cheat Sheet, Cheat Sheet of Java Programming

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