Learning Unit 3 Programming Theory

Question 1

\n (new line)

Answer 1

Forces a new line

Question 2

\t (tab space)

Answer 2

• Indicates tab space
• Cannot be used with showMessageDialog method
• Work with standard text output system.out.println()
• Leaves 8 spaces

Question 3

Not a

Answer 3

Primitive data type

Question 4

Strings are fundamental to Java

Answer 4

Has a number of features that we don’t find in other classes.
- The way a string object may be initialized.

Question 5

Initializing a string involves using

Answer 5

A resolved word new.

Question 6

You can use char.At(_) method with

Answer 6

Objects of String class.

Question 7

Positions for string start at

Answer 7

0

Question 8

Has no parameters

Answer 8

In brackets

Question 9

Java requires that any method name must be followed by an

Answer 9

Opening and closing bracket

Question 10

Can only be used with

Answer 10

String types.

Question 11

Methods of Math class are used for some

Answer 11

Are used for some mathematical operations which do not have operators in Java.

Question 12

Important skill in programming

Answer 12

Find and use methods that have already been written to achieve your goal before your try to code your own solutions.

Question 13

Method is static

Answer 13

Called using class name.

Question 14

No object needs

Answer 14

To be instantiated to call methods.

Question 15

NaN (Not a Number)

Answer 15

Is a run time error.

Question 16

Math.pow();

Answer 16

• Requires 2 parameters
• Data type type of parameters: int/double
• Function: returns the first value raised to the power of the second value.
• Data type of return: double

Question 17

Math.round();

Answer 17

• Requires: parameter
• Data type of parameter: double
• Function: returns round off value.
• Data type of return: double

Question 18

Character values are written

Answer 18

Between single quotation marks.

Question 19

Characters are represented in Java

Answer 19

By Unicode character set.

Question 20

Unicode set:

Answer 20

A big table of all the characters on the keyboard as well as many more characters from different languages, Braille patterns and all sorts of symbols.

Question 21

Each character has a unique number

Answer 21

So that the computer can identify one from another.

Question 22

There are some special characters which we use quite often but do not have a single character symbol on the keyboard

Answer 22

(new line character/ return/enter and tab character)

Question 23

Escape sequences have unique Unicode values but

Answer 23

It is more convenient and understandable to express them using escape sequences.

Question 24

Instead of system.out.println() to display text on output screen, you can use

Answer 24

showMessageDialog() method of JOptionPane class to display in GUI

Question 25

To gain access to showMessgaeDIalog method:

Answer 25

Import javax.swing.* package

Question 26

Parameter null

Answer 26

Refers to GUI component the message is displayed in (frame). Since we don't have any GUI components, we use null for the first parameter (means 'nothin').

Question 27

Two data type conversions

Answer 27

- Widening conversion - Narrowing conversion

Question 28

Java performs widening conversions

Answer 28

Automatically

Question 29

Narrowing conversions are not always safe

Answer 29

Data can be lost if value is outside possible range of values in new data type.

Question 30

Java can be forced to perform a narrowing conversion using construct known as typecast/cast

Answer 30

Placing name of the desired data type in round brackets before value can be converted.

Question 31

Narrowing conversion

Answer 31

Truncates (chops off) decimals of a real number when converting to integer.

Question 32

Conversions should be avoided

Answer 32

If accuracy is to be preserved.

Question 33

Cast operators are available

Answer 33

For several data types.

Question 34

Formed by placing parenthesis

Answer 34

Around data type name immediately in front of the value to be converted.

Question 35

No casting to convert from

Answer 35

String to int/double

Question 36

println method converts all types to

Answer 36

String before displaying them.

Question 37

Conversion could also be done by

Answer 37

Joining number to empty double quotes.