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Package java.awt Description
To type in notepad, we can make use of Robot
class.
Credits: Oracle
This post teaches you what Robot class is and how to
make use of Robot class in Java. We are going to look at some examples how to
use this Robot class.
Before jumping into the main concept, let me tell you
about the package “java.awt”. Because the Robot class is a part of “java.awt”
package.
What is a
Package?
A package is a namespace that organizes a set of
related classes and interfaces. Conceptually you can think of packages as being
similar to different folders organized on your computer to keep images in one
folder, videos in one folder. The software written in the Java programming
language can be composed of hundreds or thousands of individual classes, it
makes sense to keep things in an organized by placing then into related classed
and interfaces into packages.
The Java
platform provides an enormous class library (a set of packages) suitable for
use in your own applications. This library is known as the “Application
Programming Interface” or “API for short. Its packages represent the tasks most
commonly associated with general-purpose programming. For example, a File object allows a programmer to
easily create, delete, inspect, compare, or modify a file on the file system; a
socket object allows for the creation
and use of network sockets. This allows you, the programmer, to focus on the
design and organize a particular application in a well manner, rather than the
infrastructure required to make it work.
Package java.awt Description
This package contains all the classes for creating
user interfaces and for painting graphics and images. A user interface object
such as a button or a scrollbar is called, in AWT terminology, a component. The
component class is the root of all AWT components.
Some components fire events when a user interacts with
the components. For example, click on a button or mouse hover on a particular
component. The AWTEvent class and its
subclasses are used to represent the events that AWT components can fire.
A container is
a component that can contain components and other containers. A container can
also have a layout manager that controls the visual placement of components in
the container. The AWT package contains several layout manager classes and an
interface for building your own layout manager.
Each Component
object is limited in its maximum size and its location because the values are
stored as an integer. Also, a platform may further restrict maximum size and
location coordinates. The exact maximum values are dependent on the platform.
There is no way to change these maximum values, either in Java code or in
native code. These limitations also impose restrictions on component layout. If
the bounds of a Component object exceed a platform limit, there is no way to
properly arrange them within a Container object. The object's bounds are
defined by any object's coordinate in combination with its size on a respective
axis.
java.awt.Robot
public
class Robot extends Object
Class object is the root of the class hierarchy. Every
class has object as a super class. All objects, including arrays, implements
the methods of this class.
Robot class is used to generate native system input events
for the purposes of test automation, self-running demos, and other applications
where control of the mouse and keyboard is needed. The primary purpose of Robot
is to facilitate automated testing of Java platform implementations.
Using the class to generate input events differs from
posting events to the AWT event queue or AWT components in that the events are
generated in the platform's native input queue. For example, Robot.mouseMove will actually move the
mouse cursor instead of just generating mouse move events.
AWTException - if the platform configuration does not allow low-level input control.
This exception is always thrown when GraphicsEnvironment.isHeadless()
returns true.
SecurityException - if createRobot permission
is not granted
Sample programs
that make use of “Robot” class
Typing
on computer without typing manually
This program opens an editor like Notepad where the
program will start typing automatically.
To open an editor-
Runtime.getRuntime().exec("notepad.exe");
Thread.sleep(500);
r.keyPress(KeyEvent.VK_H);
Thread.sleep(500);
r.keyPress(KeyEvent.VK_I);
Thread.sleep(500);
r.keyPress(KeyEvent.VK_S);
Thread.sleep(500);
r.keyPress(KeyEvent.VK_SPACE);
Thread.sleep(500);
r.keyPress(KeyEvent.VK_I);
Thread.sleep(500);
r.keyPress(KeyEvent.VK_S);
Thread.sleep(500);
r.keyPress(KeyEvent.VK_SPACE);
Thread.sleep(500);
r.keyPress(KeyEvent.VK_R);
Thread.sleep(500);
r.keyPress(KeyEvent.VK_O);
Thread.sleep(500);
r.keyPress(KeyEvent.VK_B);
Thread.sleep(500);
r.keyPress(KeyEvent.VK_O);
Thread.sleep(500);
r.keyPress(KeyEvent.VK_T);
A Starting delay of 5 seconds because to give a time
to open the notepad editor, else our program writes anywhere else. After each
letter some delay seems to be somebody typing.
Screenshot
Follwing is the program to capture a screen of
particular dimension.
Dimension d_size = Toolkit.getDefaultToolkit().getScreenSize(); Robot robot = new Robot(); BufferedImage img = robot.createScreenCapture(new Rectangle(d_size)); File path_to_save = new File("Robot.jpg"); ImageIO.write(img, "JPG", path_to_save);
Here Dimension gets your screen size and puts dimension in
the d_size variable. createScreenCapture function takes a screenshot. ImageIO.write
is responsible for writing the screenshot as a JPG file.
Get
Pixel Color
Using this program you can get the color of a pixel at
the given screen coordinates.
The parameters are the X and Y positions of pixel.
public Color getPixelColor(int x,int y)
Similarly you can use the Robot class for moving the
mouse to avoid the system from sleeping in certain cases, press the mouse
buttons, key press, key release etc.
Please refer Robot class in java.awt package for more
details,
Credits: Oracle
Please write your comments if you find anything is incorrect or do you want share more information about the topic discussed above.
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what is r ??
ReplyDeleteRobot r = new Robot();
Delete