- What is meant by Controls and what are different types of controls?
Answer: Controls are componenets that allow a user to interact with your application. The AWT supports the following types of controls:
- Labels
- Push buttons
- Check boxes
- Choice lists
- Lists
- Scroll bars
- Text components
These controls are subclasses of Component.
- Which method of the component class is used to set the position and the size of a component?
Answer: setBounds(). The following code snippet explains this:
txtName.setBounds(x,y,width,height);
places upper left corner of the text field txtName at point (x,y) with the width and height of the text field set as width and height.
- Which TextComponent method is used to set a TextComponent to the read-only state?
Answer: setEditable()
- How can the Checkbox class be used to create a radio button?
Answer: By associating Checkbox objects with a CheckboxGroup.
- What methods are used to get and set the text label displayed by a Button object?
Answer: To get the text label:
getLabel( )
To set the text label:
setLabel( )
- What is the difference between a Choice and a List?
Answer: Choice: A Choice is displayed in a compact form that requires you to pull it down to see the list of available choices. Only one item may be selected from a Choice.
List: A List may be displayed in such a way that several List items are visible. A List supports the selection of one or more List items.
- What is the difference between a Scollbar and a Scrollpane?
Answer: A Scrollbar is a Component, but not a Container. A Scrollpane is a Container and handles its own events and performs its own scrolling.
- What are the subclasses of the Container class?
Answer: The Container class has three major subclasses. They are:
- Which object is needed to group Checkboxes to make them exclusive?
Answer: CheckboxGroup.
- What are the types of Checkboxes and what is the difference between them?
Answer: Java supports two types of Checkboxes:
In case of exclusive Checkboxes, only one among a group of items can be selected at a time. I f an item from the group is selected, the checkbox currently checked is deselected and the new selection is highlighted. The exclusive Checkboxes are also called as Radio buttons. The non-exclusive checkboxes are not grouped together and each one can be selected independent of the other.
