CCEA A-Level Software Systems Development CL4
Software and the Development Environment
Defining Data: Types, Variables and Classes
Program Control Structures
Objects, Classes and Data Structures
Exception Handling and Managing Input and Output
Testing an Object Oriented Application
Graphical User Interface Objects and Events
Multiple Forms and Linking to Files
Designing, Testing and Evaluating an Event Driven Application
Reasons for Systems Development and Systems Methodologies
Managing Projects
Testing Strategies
Database Concepts and Entity Relationship Modelling
Normalisation and Structured Query Language
Project Management and the Systems Approach in Practice
Defining Requirements and Documenting the Design
Building a Desktop Solution with a Database
Testing and Evaluating the Solution
Graphical User Interface Objects and Events
Lists, combo boxes and other selection controls
- 3 things to know
- AS Unit 2
Overview
List box, editable combo box and multiple selection list.
What you need to know
Answer each one before you reveal it.
What is a list box?
How does a combo box differ from a list box?
Questions from this subtopic
Each one with the model answer underneath.
- 1
What is a list box?
Model answer
A list box shows several entries at once and lets the user select one or more of them by clicking.
- 2
How does a combo box differ from a list box?
Model answer
A combo box shows only the current selection until the user opens the drop-down, so a combo box takes one line of the form instead of several.
- 3
What is an editable combo box?
Model answer
An editable combo box lets the user type a value that is not in the list as well as choose one from the drop-down.
- 4
The Java code cboSize.addItem("Small"); cboSize.addItem("Medium"); cboSize.addItem("Large"); runs on an empty combo box and nothing else is selected. What does cboSize.getSelectedIndex() return?
Model answer
The call returns 0, because the first entry added to an empty combo box becomes the selection and entry positions are counted from zero.
- 5
A combo box has had Small, Medium and Large added in that order and the user has chosen the third entry. What do getSelectedIndex and getSelectedItem each return?
Model answer
The index call returns 2 because counting starts at zero and Large is two places along, and the item call returns the wording Large.
- 6
Why is a selection control safer than a text box for a field such as county?
Model answer
A selection control offers only valid entries, so misspellings and unexpected wording never reach the program or the file.
Other ways to work this
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