Some basic GUI Methods of Java before Event Handling
Before
we move forward I would like you to know some of the methods that are
frequently used in and are important while building GUI (Graphical User
Interface) based desktop application using java language. Java has many inbuilt
methods that are used to do different task in the programming.
Some
of the Method are given below with the description and use of it;
a) setTitle(String
title): It helps to provide the title to the frame. It is not necessary to user
setTitle() method to provide the title to the frame. You can also provide title
to the frame at the time of its object creation i.e JFrame f=new JFrame(“Title
Here”);. And by using setTitle() method should be passed with the string value
which will be the title of the frame i.e f.setTitle(“Title Here”);
b) setSize(int
width,int vertical): It provides the size of the frame/container. This method
should be passed with two integer value which will be the width and height of the
frame/container i.e f.setSize(400,300);. Without this method your frame may
look like this. So it is important to call this method.
c) setDefaultCloseOperation(int
operation): This method is only applicable in case of SWING GUI. This method is
used to close the frame. setDefaultCloseOperation() method should be passed the
parameters to make it work. The value of the parameters are;
JFrame.EXIT_ON_CLOSE, JFrame.DISPOSE_ON_CLOSE, JFrame.HIDE_ON_CLOSE and
JFrame.DO_NOTHIG_ON_CLOSE.
setDefaultCloseOperation
(JFrame. EXIT_ON_CLOSE): It terminates the whole program when close button is
clicked.
setDefaultCloseOperation
(JFrame. DISPOSE_ON_CLOSE): It terminates the specific window when close button
is clicked in case of multiple window of the program.
setDefaultCloseOperation(JFrame.HIDE_ON_CLOSE):
It hides the window when user clicks to the close button and runs in
background.
setDefaultCloseOperation(JFrame.DO_NOTHIG_ON_CLOSE):
It does not do anything even if the close button is clicked.
d) setLayout(LayoutManager manager): It is the method
which is used for setting the layout in the frame. And in a frame layout must
be added in-order add the components
to the frame. It is set as setLayout(new FlowLayout();.
add(components
comp): This method is used to add the components to the frame/container. It
should be passed a component to its parameter i.e. f.add(button1);.
e) add(components
comp): This method is used to add the components to the frame/container. It
should be passed a component to its parameter i.e. f.add(button1);.
f) setVisible(boolean
b): This method is used for making the frame visible to the user. It takes a
boolean value i.e true or false. If this method is not called and not set to
true i.e setVisible(true), you cannot see the frame and the program gets
terminated automatically.
g) setText(String
text): It is used to set the text in the textbox, textarea, label and also to
set the title of the button. For example;
//for
textbox
JTextField
t;
t=new
JTextField();
t.setText(“Hello”);
//for
textarea
JTextArea
ta;
ta=new
JTextArea();
Ta.setText(“Kathmandu,Nepal);
//for
button
JButton
b1;
b1=new
JButton();
b1.setText(“Title”);
//for
label
JLabel
l;
l=new
JLabel();
l.setText(“Your
Label”);
h) getText():
It is used to retrieve the text from the textbox,label, textarea and button. It
is just opposite of the setText() method. It does not need any value to be
passed because it does not have the parameter. For example;
//retrieve
the text which is set above
JTextField
t1;
t1=new
JTextField();
String
str=t.getText(); //text of t is copied to str
//now
set the text into t1
t1.setText(str);
//t1 will show the text to t now.
So
these are the method you should know well before we start the tutorials.
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Basic GUI Methods in Java
Java Swing V/S Java AWT
