Question

For Java, can someone help me understand what the questions were asking for?

Consider the following Java declarations: JComboBox cb = new JComboBox(); JButton b = new JButton ("Press"); JCheckBox cb = new JCheckBox("Honors"); JTextField tf = new JTextField(10); Font f1 = new Font ("Serif", Font. BOLD, 12); Write a single, complete, syntactically correct Java statement in the form of a method invocation) that will perform each of the following tasks: a. Change the label on the JButton to "Submit". - JButton b= new JButton ("Submit"); b. Add "Football" so that it will be at the end of any selections currently in the JComboBox. J ComboBox cb = new J Combobox ("Football"); c. Set the state of the JCheckBox to the "checked" (i.e., selected) state. J Check Box rb = new J Check Box ("Honorst true); d. Set the color of text entered into the JTextField to red. JTextField tf = new JTextField(set Color. RED); e. Clear any text that has been entered into the JTextField(i.e., the JTextField should now be empty of all text). JTextField tf= new JTextField(); f. Change the Font of text appearing on the JButton to the f1 font. J Button rb = new JButton ("Press"); add.ro fl

Answer 1

Java Swing is a platform independent Graphical User Interface (GUI) toolkit.

Note:

• All components in swing are JComponent that must be added to container classes.
• Mainly 3 types of containers are there. That is, Panel, Frame and Dialogue.
• We must add all of the swing components to any of the container object.

Working with swing, we should add the below statement.

import javax.swing.*;

The javax.swing package contains classes for java swing API such as JTextField, JButton, JTextArea, JRadioButton, JCheckbox, etc.

• In the above question,we can see that there are five classes are defined with their objects  jcombobox, JButton, JCheckBox, JTextField and Font.
• So we dont want to define or creating the object of these classes again. Just make changes of the created classes. When we define a statement with new keyword, we are recreating the object of the class.
• There are so many methods are available in swing.

• Some of them are given below.

1) b.setLabel("Submit");

We are already created a jbutton with b as object having a label "Press", To change this label use setLabel() method.

button_object.setLabel(newlabel) is the syntax

2) cb.addItem("Football");

We are created a combobox with object cb. We have to add an item to the end of the list. So, we can use a method addItem() to add item to the combo.

syntax is, object_name.addItem(value);

object_name is the name of the component object. Here cb is the object.

3) rb.setSelected(true);

To set the checkbox to be checked by default, we have set the setSelected to true.The method setSelected() is used to check or uncheck the component. When the value is true, it become checked otherwise unchecked.

4)

//import java.awt.Color;

tf.setForeground(Color.RED);

We should import the Color class. To set the text colour ina textfield, we have to use a method called setForground() method. In the bracket, use Color.color_name. Color_name may be RED, GREEN,BLUE etc. object_name is the textbox's object name.

5) tf.setText("");

To clear the textfield use SetText() method with parametee as two double quotes. If want to set hai as text, type "hai" within the textbox. Like that, empty setText means clear the textfield content. It is also use with textfield object tf.

6)b.setFont(f1);

Here we can see that, the Font class is created with an object f1, which defines Serif as font, BOLD as text style and font size is 12. So font object f1 has all these property. Use setFont() method to change the font in the component.