Chapter 2

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Chapter 2

Console Input and Output

This activity contains 15 questions.

Can you use ConsoleIn.readLine() just like you'd use the readLine() method in BufferedReader?

No. The latter reads an entire line, returning it as a string; while the former just reads a string.No. The two methods really perform different functions and must be used differently.Yes. Both methods perform essentially identical functionsNo. The former reads an entire line, returning it as a string; while the latter just reads a string.

Can you use the ConsoleIn methods to acquire input using windows (dialogs)?

Yes. Just use the appropriate showXXX methodNo. ConsoleIn ONLY inputs from the keyboard, there is no window (dialog) interfaceYes, but in order to do so you must both import JOptionPane and then use the appropriate ConsoleIn readXXX method in order to do thisYes, but you must import the JOptionPane package

In order to use the ConsoleIn methods you must:

Just place the ConsoleIn .java files in the same directory as the Java compilerJust place import java.ConsoleIn.*; at the top of your programJust place the ConsoleIn .class files in the same directory as your Java source codeNothing is required, since the ConsoleIn methods already are available to Java

JOptionPane can be used:

is built into Java and so doesn't require an explicit import statementonly for acquiring input from a useralways yields a number - whatever number the user entersto prompt a user for input, providing a small amount of contextual information

The DecimalFormat class:

Always is used with a pattern to specify how a number is to be formatted
Always requires an import statement if you intent to use the class
Can be used to format currency if you wish
Can format integers as well as floating point numbers
Only can be used within a print() or println() method

All but (c) and (e)All (a) - (e)All but (d)All but (e)

The showMessageDialog method in JOptionPane:

provides a single line for text entry when it is invokedprovides a single line for numeric entry when it is invokedis just like the showInputDialog method, except that it doesn't have a Cancel buttononly provides for the display of a text string, and an OK button

The System.out.println() method:

prints its argument, and then prints an end-of-lineis the same as the System.out.print() methodhas the same effect as System.out.print('\n' + )prints an end-of-line, then prints its argument

What does the phrase "echo input" mean?

"Echo input" means to display a message to the user telling that the input was acquired successfully"Echo input" means to display to the user what was meant by the input that was typed"Echo input" means to display to the user a copy of what was input"Echo input" means to display the words: "Echo" and "Input"

What happens if you press the Cancel button when showInputDialog is displaying an input dialog?

An empty string, "", is returned; and your program terminatesThe constant, null, is returned; and your program terminatesThe value, zero, is returned; and your program terminatesNothing is returned; and your program terminates

What is a Java "package?"

A Java package is a library of classes that are available when you import themA Java package is a group of classes that become available to your program as soon as you first reference themA Java package is a library of Java source programs that are available when you include themA Java package is a collection of libraries that are predefined and are available to your program without further specification

What is one package that does not require an explicit import statement?

java.langjava.utiljava.textjava.ConsoleIO

What is printed by this code fragment:

NumberFormat nf = 
                  NumberFormat.getCurrencyInstance();
System.out.println("value=" + nf.format(05.0505));

value=$5.05value=$05.05value=$5.0505value=05.05

What is the difference between '0' and '#' in a format string used with DecimalFormat?

Both represent optional digits - '0' for non-zero values, and '#' for any value'0' represents an optional digit; '#' represents a required digit'0' may display as a + or a -, while '#' never does so'0' represents a required digit; '#' represents an optional digit

What is the function of JOptionPane.YES_NO_OPTION?

This constant forces JOptionPane to display Yes and No buttons instead of OK and Cancel when used with the showConfirmDialog method This constant forces JOptionPane to display Yes and No buttons instead of OK and Cancel when used with the showInputDialog methodThis constant forces JOptionPane to display Yes and No buttons instead of OK and Cancel when used with any of its showXXX methodsIt allows the showMessageDialog to display Yes and No buttons instead of just OK

What is the most important difference between using JOptionPane for input and using BufferedReader for input?

The former only allows the input of strings, while the latter allows numeric input as wellThe latter uses windows (dialogs) to acquire input, while the former only requires the user to type on the keyboardThe former uses windows (dialogs) to acquire input, while the latter only requires the user to type on the keyboardYou import different packages in order to make these input functions work

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Chapter 2

Can you use ConsoleIn.readLine() just like you'd use the readLine() method in BufferedReader?

Can you use the ConsoleIn methods to acquire input using windows (dialogs)?

In order to use the ConsoleIn methods you must:

JOptionPane can be used:

The showMessageDialog method in JOptionPane:

The System.out.println() method:

What does the phrase "echo input" mean?

What happens if you press the Cancel button when showInputDialog is displaying an input dialog?

What is a Java "package?"

What is one package that does not require an explicit import statement?

What is printed by this code fragment: NumberFormat nf = NumberFormat.getCurrencyInstance(); System.out.println("value=" + nf.format(05.0505));

What is the difference between '0' and '#' in a format string used with DecimalFormat?

What is the function of JOptionPane.YES_NO_OPTION?

What is the most important difference between using JOptionPane for input and using BufferedReader for input?

What is printed by this code fragment:
NumberFormat nf = NumberFormat.getCurrencyInstance(); System.out.println("value=" + nf.format(05.0505));