Java cheat sheet

Java Programming Guide - Quick Reference Java Programming Guide - Quick Reference

Syntax for a standalone application in Java: Java Comments:

class <classname> Delimiters Use
{ // Used for commenting a single line
public static void main(String args[])
{ /* ————— */ Used for commenting a block of code
statements;
————————; /** —————*/ Used for commenting a block of code.
————————; Used by the Javadoc tool for
} generating Java documentation.
}
Primitive datatypes in Java:
Steps to run the above application:

1. Type the program in the DOS editor or notepad. Save the DataType Size Default Min Value
file with a .java extension. Max Value
2. The file name should be the same as the class, which has the byte
main method. (Signed -128
3. To compile the program, using javac compiler, type the integer) 8 bits 0 +127
following on the command line:
Syntax: javac <filename.java> short
Example: javac abc.java (Signed -32,768
4. After compilation, run the program using the Java integer) 16 bits 0 +32,767
interpreter.
Syntax: java <filaname> (without the .java int
extension) (Signed -2,147,483,648
Example: java abc integer) 32 bits 0 +2,147,483,647
5. The program output will be displayed on the command line.
long -9, 223, 372,036,854,
(Signed 775,808,
Integer) +9,223,372,036,
64 bits 0 854, 775, 807

© 1999, Pinnacle Software Solutions Inc. 1 © 1999, Pinnacle Software Solutions Inc. 3


Java reserved words:

abstract default if package this float 32 bits 0.0 1.4E-45
boolean do implements private throw (IEEE 754 3.4028235E38
Break double import protected throws floating-point)
Byte else instanceof public transient
case extends int return null double 64 bits 0.0 4.9E-324
try Const for new switch (IEEE 754 1.7976931348623157E308
continue while goto synchronized super floating-point)
Catch final interface short void
char finally long static volatile
class float native
char 16 bits u0000 u0000
(Unicode
character) uFFFF
Java naming conventions:
boolean 1 bit false
Variable Names: Can start with a letter, ‘$’ (dollar symbol),
or ‘_’ (underscore); cannot start with a number; cannot be a
reserved word.
Variable Declaration:
Method Names: Verbs or verb phrases with first letter in <datatype> <variable name>
lowercase, and the first letter of subsequent words Example: int num1;
capitalized; cannot be reserved words.
Example: setColor() Variable Initialization:
<datatype> <variable name> = value
Class And Interface Names: Descriptive names Example: double num2 = 3.1419;
that begin with a capital letter, by convention; cannot be a
reserved word. Escape sequences:
Literal Represents
Constant Names: They are in capitals. n New line
Example: Font.BOLD, Font.ITALIC t Horizontal tab
b Backspace
r Carriage return



5. Switch statement
f Form feed Syntax:
Backslash switch(variable)
” Double quote {
ddd Octal character case(value1):
xdd Hexadecimal character statements;
udddd Unicode character break;
case(value2):
statements;
Arrays: An array which can be of any datatype, is created in break;
two steps – array declaration and memory allocation. default:
statements;
Array declaration break;
<datatype> [] <arr ```````````ayname>; }
Examples int[] myarray1;
double[] myarray2; Class Declaration: A class must be declared using the
Memory Allocation keyword class followed by the class name.
The new keyword allocates memory for an array. Syntax
Syntax class <classname>
<arrayname> = new <array type> [<number of {
elements>]; ———— Body of the class
Examples
myarray1 = new int[10]; A typical class declaration is as follows:
Myarray2 = new double[15]; <modifier> class <classname> extends
<superclass name> implements <interface name>
Multi-dimensional arrays: {
—————Member variable declarations;
Syntax: —————Method declarations and definitions
<datatype> <arrayname> [] [] = new <datatype> }
[number of rows][number of columns];
Example:
int mdarray[][] = new int[4][5];



Flow Control: Member variable declarations:

1. If……..else statements <access specifier> <static/final/transient/
Syntax: volatile> <datatype> <variable name>
if(condition) Example public final int num1;
{
statements; Method declarations:
}
else <access specifier> <static/final> <return type>
{ <method name> <arguments list>
statements; {
} Method body;
}
2. For loop Example public static void main(String args[])
Syntax: {
for(initialization; condition; increment) }
{
statements; Interface declaration: Create an interface. Save the file
} with a.java extension, and with the same name as the
interface. Interface methods do not have any implementation
3. While loop and are abstract by default.
Syntax:
while(condition) Syntax
{ interface <interface name>
statements; {
} void abc();
void xyz();
4. Do….While loop }
Syntax:
do Using an interface: A class implements an interface with the
{ implements keyword.
statements;
}
while(condition);


Syntax
class <classname> extends <superclass name>
implements <interface name> final Class Cannot be subclassed.
{
class body; Method Cannot be overridden.
—————————;
} Variable Value cannot be changed
(Constant)
Creating A Package:
native Method Implemented in a language
1. Identify the hierarchy in which the .class files have to other than Java like C,C++,
be organized. assembly etc. Methods do not
2. Create a directory corresponding to every package, with have bodies.
names similar to the packages.
3. Include the package statement as the first statement in static Method Class method. It cannot refer to
the program. nonstatic variables and methods
4. Declare the various classes. of the class. Static methods are
5. Save the file with a .java extension. implicitly final and invoked
6. Compile the program which will create a .class file in through the class name.
the same directory.
7. Execute the .class file. Variable Class variable. It has only one
copy regardless of how many
Packages and Access Protection: instances are created. Accessed
only through the class name.
Accessed Public Protected Package Private
From the synchronized Method A class which has a synchronized
same class ? Yes Yes Yes Yes method automatically acts as a
lock. Only one synchronized
From a non method can run for each class.
subclass in
the same
package ? Yes Yes Yes No



List of exceptions in Java(part of java.lang package):
From a non
subclass Essential exception classes include -
outside the
package? Yes No No No Exception Description

From a ArithmeticException Caused by exceptional
subclass conditions like divide by
in the same zero
package? Yes Yes Yes No
ArrayIndexOfBounds Thrown when an array is
From a Exception accessed beyond its bounds
subclass
outside the ArrayStoreException Thrown when an incompatible
package ? Yes Yes No No type is stored in an array

ClassCastException Thrown when there is an invalid
cast
Attribute modifiers in Java:
IllegalArgument Thrown when an inappropriate
Modifier Acts on Description Exception argument is passed to a method
abstract Class Contains abstract
methods.Cannot IllegalMonitorState Illegal monitor operations such as
be instantiated. Exception waiting on an unlocked thread

Interface All interfaces are implicitly IllegalThreadState Thrown when a requested
abstract. The modifier is Exception operation is incompatible with
optional. the current thread state.

Method Method without a body. IndexOutOfBounds Thrown to indicate that an index
Signature is followed by a Exception is out of range.
semicolon. The class must also
be abstract. NegativeArraySize Thrown when an array is created
Exception with negative size.


NullPointerException Invalid use of a null reference. setPriority() Changes the priority of the thread

NumberFormatException Invalid conversion of a string to a currentThread() Returns a reference to the
number. currently executing thread

SecurityException Thrown when security is violated. activeCount() Returns the number of active
threads in a thread group
ClassNotFound Thrown when a class is not found.
Exception
Exception Handling Syntax:
CloneNotSupported Attempt to clone an object that
Exception does not implement the Cloneable try
interface. {
//code to be tried for errors
IllegalAccess Thrown when a method does not }
Exception have access to a class. catch(ExceptionType1 obj1)
{
Instantiation Thrown when an attempt is made //Exception handler for ExceptionType1
Exception to instantiate an abstract class or }
an interface. catch(ExceptionType2 obj2)
{
InterruptedException Thrown when a second thread //Exception handler for ExceptionType2
interrupts a waiting, sleeping, or }
paused thread. finally{
//code to be executed before try block ends.
This executes whether or not an //
exception occurs in the try block.
}

The java.lang.Thread class I/O classes in Java (part of the java.io package):

The Thread class creates individual threads. To create a thread I/O class name Description
either (i) extend the Thread class or (ii) implement the Runnable
interface. In both cases, the run() method defines operations BufferedInputStream Provides the ability to buffer the



performed by the thread.
input. Supports mark() and
Methods of the Thread class: reset() methods.
BufferedOutputStream Provides the ability to write bytes
Methods Description to the underlying output stream
without making a call to the
run() Must be overridden by underlying system.
Runnable object; contains code
that the thread should perform BufferedReader Reads text from a character
start() Causes the run method to input stream
execute and start the thread BufferedWriter Writes text to character
output stream
sleep() Causes the currently executing DataInputStream Allows an application to read
thread to wait for a specified time primitive datatypes from an
before allowing other threads to underlying input stream
execute DataOutputStream Allows an application to write
primitive datatypes to an output
interrupt() Interrupts the current thread stream
File Represents disk files and
Yield() Yields the CPU to other runnable directories
threads FileInputStream Reads bytes from a file in a file
system
getName() Returns the current thread’s name FileOutputStream Writes bytes to a file
ObjectInputStream Reads bytes i.e. deserializes
getPriority() Returns the thread’s priority as an objects using the
integer readObject() method
ObjectOutputStream Writes bytes i.e. serializes
isAlive() Tests if the thread is alive; returns objects using the
a Boolean value writeObject()method
PrintStream Provides the ability to print
join() Waits for specified number of different data values in an
milliseconds for a thread to die efficient manner
RandomAccessFile Supports reading and writing to
setName() Changes the name of the thread a random access file


StringReader Character stream that reads getName() Returns the name of the file and directory
from a string denoted by the path name
isDirectory() Tests whether the file represented by the
StringWriter Character stream that writes to pathname is a directory
a StringBuffer that is later lastModified() Returns the time when the file was last
converted to a String modified
l length() Returns the length of the file represented by
the pathname
The java.io.InputStream class: The InputStream class is listFiles() Returns an array of files in the directory
at the top of the input stream hierarchy. This is an abstract class represented by the pathname
which cannot be instantiated. Hence, subclasses like the setReadOnly() Marks the file or directory so that only
DataInputStream class are used for input purposes. read operations can be performed
renameTo() Renames the file represented by the
Methods of the InputStream class: pathname
delete() Deletes the file or directory represented by
Method Description the pathname
available() Returns the number of bytes that can be canRead() Checks whether the application can read
read from the specified file
canWrite() Checks whether an application can write to
close() Closes the input stream and releases a specified file
associated system resources

mark() Marks the current position in the input Creating applets:
stream
mark 1. Write the source code and save it with a .java
Supported() Returns true if mark() and reset() methods extension
are supported by the input stream 2. Compile the program
3. Create an HTML file and embed the .class file with the
read() Abstract method which reads the next byte <applet> tag into it.
of data from the input stream 4. To execute the applet, open the HTML file in the browser
or use the appletviewer utility, whch is part of the Java
read(byte b[]) Reads bytes from the input stream and Development Kit.
stores them in the buffer array



skip() Skips a specified number of bytes from the The <applet> tag: Code, width, and height are
input stream mandatory attributes of the <applet> tag. Optional attributes
include codebase, alt,name, align, vspace, and
hspace. The code attribute takes the name of the class file as
The java.io.OutputStream class: The OutputStream class its value.
which is at the top of the output stream hierarchy, is also an Syntax:
abstract class, which cannot be instantiated. Hence, subclasses <applet code = “abc.class” height=300
like DataOutputStream and PrintStream are used for width=300>
output purposes. <param name=parameterName1 value= value1 >
<param name=parameterName2 value= value2 >
Methods of the OutputStream class: </applet>

Method Description Using the Appletviewer: Appletviewer.exe is an
application found in the BIN folder as part of the JDK. Once an
close() Closes the output stream, and releases HTML file containing the class file is created (eg. abc.html),
associated system resources type in the command line:
Appletviewer abc.html
write(int b) Writes a byte to the output stream
java.applet.Applet class:
write(byte b[]) Writes bytes from the byte array to the
output stream Methods of the java.applet.Applet class:

flush() Flushes the ouput stream, and writes Method Description
buffered output bytes
init() Invoked by the browser or the
applet viewer to inform that the
java.io.File class: The File class abstracts information applet has been loaded
about files and directories. start() Invoked by the browser or the
applet viewer to inform that
Methods of the File class: applet execution has started
stop() Invoked by the browser or the
Method Description applet viewer to inform that
applet execution has stopped
exists() Checks whether a specified file exists


destroy() Invoked by the browser or the setBackground() Sets the background color of the
appletviewer to inform that the component
applet has been reclaimed by the setForeground() Sets the foreground color of the
Garbage Collector component
getAppletContext() Determines the applet context or SetSize() Resizes the component
the environment in which it runs setLocation() Moves the component to a new
getImage() Returns an Image object that can location
be drawn on the applet window setBounds() Moves the component to specified
location and resizes it to the
getDocumentBase() Returns the URL of the HTML page specified size
that loads the applet addFocusListener() Registers a FocusListener
object to receive focus events
getCodeBase() Returns the URL of the applet’s from the component
class file addMouseListener() Registers a MouseListener
getParameter() Returns the value of a named object to receive mouse events
applet parameter as a string from the component
showStatus() Displays the argument string on addKeyListener() Registers a KeyListener object
the applet’s status to receive key events from the
component
getGraphics() Returns the graphics context of
java.awt.Graphics class: The Graphics class is an this component
abstract class that contains all the essential drawing methods update(Graphics g) Updates the component. Calls the
like drawLine(), drawOval(), drawRect() and so on. A paint() method to redraw the
Graphics reference is passed as an argument to the paint() component.
method that belongs to the java.awt.Component class.

Methods of the Graphics class: AWT Components: Many AWT classes like Button,
Checkbox, Label, TextField etc. are subclasses of the
Method Description java.awt.Component class. Containers like Frame and
drawLine() Draws a line between (x1,y1) and Panel are also subclasses of components, but can additionally
(x2,y2) passed as parameters hold other components.
drawRect()/fillRect() Draws a rectangle of specified
width and height at a specified



Label:
location
Constructors
drawOval()/fillOval() Draws a circle or an ellipse that · Label() - Creates an empty label
fills within a rectangle of specified · Label(String s) - Creates a label with left
coordinates justified text string
drawString() Draws the text given as a · Label (String s, int alignment) - Creates
specified string a label with the specified text and specified aligment.
drawImage() Draws the specified image onto Possible values for alignment could be Label.RIGHT,
the screen Label.LEFT, or Label.CENTER
drawPolygon()
/fillPolygon() Draws a closed polygon defined Methods of the Label class:
by arrays of x and y coordinates
Method Description
setColor() Sets the specified color of the
graphics context getAlignment() Returns an integer representing
the current alignment of the Label.
setFont() Sets the specified font of the 0 for left, 1 for center, and 2 for
graphics context right alignment.
setAlignment() Sets the alignment of the Label to
the specified one
java.awt.Component class: The Component class is an getText() Returns the label’s text as a
abstract class that is a superclass of all AWT components. A string
component has a graphical representation that a user can setText() Sets the label’s text with the
interact with. For instance, Button, Checkbox, specified string
TextField, and TextArea.

Methods of the Component class: Button:

Method Description Constructors

paint(Graphics g) Paints the component. The Button() - Creates a button without a label
Graphics context g is used for Button(String s) - Creates a button with the specified
painting. label


Methods of the Button class:
Choice() - Creates a new choice menu, and presents a pop-
Method Description up menu of choices.
addActionListener() Registers an ActionListener
object to receive action events Methods of the Choice class:
from the button
Method Description
getActionCommand() Returns the command name of
the action event fired by the add() Adds an item to a choice menu
button. Returns the button label
if the command name is null. addItem() Adds an item to a choice menu

GetLabel() Returns the button’s label addItemListener() Registers an ItemListener object
to receive item events from the
SetLabel() Sets the button’s label to the Choice object
specified string
getItem() Returns the item at the specified
index as a string
Checkbox:
getItemCount() Returns the number of items in the
Constructors choice menu

· Checkbox() - Creates a checkbox without any label getSelectedIndex() Returns the index number of the
· Checkbox(String s) - Creates a checkbox with a currently selected item
specified label
· Checkbox(String s, boolean state) - Creates getSelectedItem() Returns the currently selected item
a checkbox with a specified label, and sets the specified as a string
state
· Checkbox(String s, boolean state, insert() Inserts a specified item at a specified
CheckboxGroup cbg) - Creates a checkbox with a index position
specified label and specified state, belonging to a
specified checkbox group remove() Removes an item from the choice
menu at the specified index



Methods of the Checkbox class: TextField:

Method Description Constructors

addItemListener() Registers an ItemListener · TextField() - Creates a new text field
object to receive item events from · TextField(int cols) - Creates a text field with the
the checkbox specified number of columns
· TextField(String s) – Creates a text field initialized with
getCheckboxGroup() Returns the checkbox’s group a specified string
· TextField(String s, int cols) - Creates a text field
getLabel() Returns the checkbox’s label initialized with a specified string that is wide enough to hold a
specified number of columns
getState() Determines if the checkbox
is checked or unchecked Methods of the TextField class:

setLabel() Sets the label of the check box Method Description
with the specified string
isEditable() Returns a boolean value indicating
setState() Sets the specified checkbox state whether or not a text field is
editable

setEditable() Passing True enables text to be
Creating Radio Buttons (Mutually exclusive checkboxes): edited, while False disables
editing. The default is True.
· First create a CheckboxGroup instance –
CheckboxGroup cbg = new CheckboxGroup(); addActionListener() Registers an ActionListener
· While creating the checkboxes, pass the checkbox group object to receive action events
object as an argument to the constructor - Checkbox from a text field
(String s, boolean state, CheckboxGroup
cbg) getEchoChar() Returns the character used for
echoing
Choice:
getColumns() Returns the number of columns
Constructors in a text field


setEchoChar() Sets the echo character for a text Methods of the List class:
field
getText() Returns the text contained in the Method Description
text field
setText() Sets the text for a text field add() Adds an item to the end of the
scrolling list

TextArea: addItemListener() Registers an ItemListener
object to receive Item events from
Constructors a scrolling list

· TextArea() - Creates a new text area deselect() Deselects the item at the specified
· TextArea(int rows, int cols) - Creates a new index position
empty text area with specified rows and columns
· TextArea(String s) – Creates a new text area with the getItem() Returns the item at the specified
specified string index position
· TextArea(String s, int rows, int cols) - Creates
a new text area with the specified string and specified rows getItemCount() Returns the number of items in the
and columns. list
· TextArea(String s, int rows, int cols, int
scrollbars) - Creates a text area with the specified text, getSelectedIndex() Returns the index position of the
and rows, columns, and scrollbar visibility as specified. selected item

Methods of the TextArea class: getSelectedItem() Returns the selected item on the
scrolling list
Method Description
isMultipleMode() Determines if the scrolling
getText() Returns the text contained in the list allows multiple selection
text area as a string
remove() Removes a list item from a
setText() Sets the specified text in the text specified position
area
setMultipleMode() Sets a flag to enable or disable
getRows() Returns the number of rows in the multiple selection

© 1999, Pinnacle Software Solutions Inc. © 1999, Pinnacle Software Solutions Inc.

Scrollbar:

Constructors
text area
getColumns() Returns the number of columns in · Scrollbar() - Creates a new vertical scroll bar
the text area · Scrollbar(int orientation) - Creates a new scroll
bar with a particular orientation, which is specified as
selectAll() Selects all the text in the text area Scrollbar.HORIZONTAL or Scrollbar.VERTICAL
· Scrollbar(int orientation, int value,
setEditable() A True value passed as an int visible, int minimum, int maximum)- Creates
argument enables editing of the a new scroll bar with the specified orientation, initial value,
text area, while False disables thumb size, minimum and maximum values
editing. It is True by default.
Methods of the Scrollbar class:

List: Method Description

Constructors addAdjustmentListener() Registers an
adjustmentListener object
· List() - Creates a new scrolling list to receive adjustment
· List(int rows) - Creates a new scrolling list with a events from a scroll bar
specified number of visible lines getBlockIncrement() Returns the block
· List(int rows, boolean multiple) - Creates a increment of a scrollbar
scrolling list to display a specified number of rows. A True as an integer.
value for Multiple allows multiple selection, while a False getMaximum() Returns the maximum
value allows only one item to be selected. value of a scrollbar as an
integer
getMinimum() Returns the minimum
value of a scrollbar as an
integer
getOrientation() Returns the orientation of
a scrollbar as an integer
getValue() Returns the current value
of a scrollbar as an integer



Interface method Description
setOrientation() Sets the orientation of a scrollbar
setValue() Sets the current value of a actionPerformed() Invoked whenever an ActionEvent
scrollbar object is generated (button is
setMinimum() Sets the minimum value of a clicked)
scrollbar
setMaximum() Sets the maximum value of a
scrollbar TextListener interface: Implemented by a class to handle
text events. Whenever the text value of a component changes,
an interface method called textValueChanged is invoked,
Frame: which must be overridden in the implementing class.

Constructors Interface method Description

· Frame() - Creates a new frame without any title textValueChanged() Invoked whenever a Text
· Frame(String s) - Creates a new frame with the Event object is generated (text
specified title value changes)

Menus:
AdjustmentListener interface: Implemented by a class that
· Can be added only to a frame handles adjustment events. The method
· A MenuBar instance is first created as: adjustmentValueChanged(), overridden by the
MenuBar mb = new MenuBar(); implementing class is invoked everytime an AdjustmentEvent
· The MenuBar instance is added to a frame using the object occurs (when a scrollbar is adjusted).
setMenuBar() method of the Frame class as follows:
setMenuBar(mb); Interface method Description
· Individual menus are created (instances of the Menu class) adjustmentValueChanged() Invoked whenever an
and added to the menu bar with the add() method AdjustmentEvent object is
generated (when a scrollbar
Dialog: Direct subclass of java.awt.Window, which accepts thumb is adjusted)
user input.
ItemListener interface: Implemented to handle state change
events. The method itemStateChanged()must be overridden
by the implementing class.



Constructors Method Description
itemStateChanged() Invoked whenever an ItemEvent
· Dialog(Frame parent, boolean modal) – Creates a object is generated (a checkbox is
new initially invisible Dialog attached to the frame object checked, an item is selected from a
parent. The second argument specifies whether the dialog choice menu, or an item is selected
box is Modal or Non-modal. from a list)
· Dialog (Frame parent, String s, boolean modal)
– Same as the above. The second argument specifies the title FocusListener interface: Implemented to receive
of the dialog box. notifications whenever a component gains or loses focus. The
two methods to be overridden are focusGained() and
FileDialog: Direct subclass of Dialog, which displays a dialog focusLost(). The corresponding adapter class is
window for file selection. FocusAdapter.

Constructors Method Description

· FileDialog(Frame f, String s) - Creates a new focusGained() Invoked whenever a component
dialog for loading files(file open dialog) attached to the frame gains keyboard focus
with the specified title focusLost() Invoked whenever a component
· FileDialog(Frame f, String s, int i) - Creates a loses keyboard focus
file dialog box with the specified title. The third argument
specifies whether the dialog is for loading a file or saving a file.
The value of i can be either FileDialog.LOAD or KeyListener interface: Implemented to handle key events.
FileDialog.SAVE Each of the three methods – keyPressed(),
keyReleased(), keyTyped() – receives a KeyEvent
AWT Event Listener interfaces: For every AWT event class object when a key event is generated.
there is a corresponding event-listener interface, which is a part
of the java.awt.event package and provides the event- Method Description
handling methods.
KeyPressed() Invoked whenever a key is
ActionListener interface: Implemented by a class that pressed
handles an action event. The method actionPerformed()
must be overridden by the implementing class. keyReleased() Invoked whenever a key is
released

© 1999, Pinnacle Software Solutions Inc. © 1999, Pinnacle Software Solutions Inc. 36


keyTyped() Invoked whenever a key is typed windowDeactivated() Invoked when the window is no
longer the active window i.e. the
window can no longer receive
keyboard events
MouseListener interface: Implemented by a class handling
mouse events. It comprises of five methods invoked when a windowIconified() Invoked when a normal window is
MouseEvent object is generated. Its corresponding adapter minimized
class is the MouseAdapter class.
windowDeiconified() Invoked when a minimized
Method Description window is changed to normal
state
mouseClicked() Invoked when mouse is clicked
on a component
java.sql.Driver interface: Implemented by every driver
mouseEntered() Invoked when mouse enters a class.
component
Methods of the Driver interface:
mouseExited() Invoked when mouse exits a
component Method Description

mousePressed() Invoked when mouse button is acceptsURL() Returns a Boolean value indicating
pressed on a component whether the driver can open a
connection to the specified URL
mouseReleased() Invoked when mouse button is
released on a component connect() Tries to make a database connection
to the specified URL

MouseMotionListener interface: Implemented by a class getMajorVersion() Returns the driver’s major version
for receiving mouse-motion events. Consists of two methods – number
mouseDragged() and mouseMoved(), which is invoked
when a MouseEvent object is generated. getMinorVersion() Returns the driver’s minor version
MouseMotionAdapter is its corresponding adapter class. number



jdbcCompliant() Tests whether the driver is a genuine
JDBC compliant driver
Method Description
java.sql.Connection interface: Represents a session with a
mouseDragged() Invoked when the mouse is pressed on specific database. SQL statements are executed within a session
a component and dragged and the results are returned.

mouseMoved() Invoked when mouse is moved over Methods of the Connection interface:
a component

Method Description
WindowListener interface: Implemented by a class to
receive window events. It consists of seven different methods to Close() Immediately releases the database
handle the different kinds of window events, which are invoked and JDBC resources
when a WindowEvent object is generated. Its corresponding
adapter class is the WindowAdapter class. commit() Makes all changes since the last
commit/rollback permanent, and
Method Description releases the database locks held by
the connection
windowOpened() Invoked when the window is
made visible for the first time createStatement() Creates and returns a Statement
object. It is used for sending SQL
windowClosing() Invoked when the user attempts statements to be executed on the
to close the window from the database
Windows system menu
getMetaData() Returns a DatabaseMetaData
windowClosed() Invoked when the window has object that represents metadata
been closed as a result of calling about the database
the dispose() method
isReadOnly() Checks whether the connection is a
windowActivated() Invoked when the window is read-only connection
made active i.e. the window can
receive keyboard events prepareCall() Creates and returns a
Callable Statement object,



prepareCall() Creates and returns a
CallableStatement object
(used for calling database stored
procedures)
prepareStatement() Creates and returns a
PreparedStatement
object (used for sending
precompiled SQL statements to
the database)
rollback() Discards all the changes made
since the last commit/rollback
and releases database locks held
by the connection
setAutoCommit() Enables or disables the auto
commit feature. It is disabled by
default

java.sql.DriverManager class: Responsible for managing a
set of JDBC drivers. It attempts to locate and load the JDBC
driver specified by the getConnection() method.

Methods of the DriverManager class:

Method Description

getConnection() Attempts to establish a database
connection with the specified
database URL, and returns a
Connection object

getLoginTimeout() Returns the maximum number of
seconds a driver can wait when
attempting to connect to the
database


registerDriver() Registers the specified driver with
the DriverManager

setLoginTimeout() Sets the maximum number of
seconds a driver can wait when
attempting to connect to the
database

getDrivers() Returns an enumeration of all the
drivers installed on the system

getDriver() Returns a Driver object that
supports connection through a
specified URL


Java cheat sheet

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Java cheat sheet