Java Standard Library

Question 1

JOptionPane

Answer 1

A GUI for text input and output located in javax.swing

Question 2

showInputDialog(String prompt)

Answer 2

Prints the prompt and returns the string entered by user

Question 3

showMessageDialog(String message)

Answer 3

Generates a message box

Question 4

showConfirmDialog()

Answer 4

Generates a message box

Question 5

showConfirmDialog(null, prompt, title, optionType)

Answer 5

Creates a confirmation window

Question 6

java.lang

Answer 6

General support - string, integer, float, math

Question 7

Package for general utilities

• random numbers
• currency
• calendar
• data structures

Answer 7

java.util

Question 8

Package for formatting text

• dates
• currency

Answer 8

java.text

Question 9

Package for basic graphics & GUIs

Answer 9

java.awt

Question 10

Package extending awt with advanced GUIs

Answer 10

javax.swing

Question 11

Package with functions for I/O and formatting

Answer 11

java.io

Question 12

Package for writing applets

Answer 12

java.applet

Question 13

Which package is automatically imported into all programs?

Answer 13

java.lang

Question 14

String method for length

Answer 14

S.length();

Question 15

String method for comparing the content of strings. Return type.

Answer 15

s.equals(t);

Boolean

Question 16

String method for comparing lexicographically. Return type.

Answer 16

s.compareTo(t);

0 - equal
> 0 - First string greater
< 0 - Second string is greater

Question 17

String method for comparing address references

Answer 17

==

Question 18

String method for lexicographical comparison disregarding case

Answer 18

s.compareToIgnoreCase(t);

Question 19

String method to access a character at a given index (0 to length - 1)

Answer 19

char c = s.charAt(0);

Question 20

String method for changing case

Answer 20

String x = s.toLowerCase();

String x = s.toUpperCase;

Question 21

Absolute value method

Answer 21

double x = Math.abs(-14.3);

Question 22

Square Root Method

Answer 22

double x = Math.sqrt(2.0);

Question 23

Trig methods

Answer 23

double x = Math.cos(y);

double x = Math.sin(y);

Question 24

Powers method

Answer 24

double x = Math.pow(base, exponent);

Question 25

Random numbers method

Return range

Answer 25

double x = Math.random();

0.0 to 1.0

Question 26

The class that formats text

Answer 26

Number Format in java.text

Question 27

Currency Conversion

Answer 27

Generate a currency object assigned to x
NumberFormat.getCurrencyInstance();

Generate the String
Double amount = 123.5
x.format(amount);

Question 28

Percentage Conversion

Answer 28

Generate a percent object assigned to x
NumberFormat.getPercentInstance();

Generate a string & format
double taxrate = 0.079;
percent.format(taxrate);