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Description
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shown to student

Make a short recorder that can store a message to be played back. It should have the following API:
<ul>
<li><tt>public Recorder(String initialMsg) // create new recorder w/this message initially
<li><tt>public String playback() // return the saved message
<li><tt>public void record(String newMsg) // save this message instead</tt>
</ul>

Epilogue
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Remarks
Comments, history, license, etc.

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Engine
Choices
json list of string, bool pairs
e.g. [["good", true], ["bad", false]]

Correct answer
Template / Reference solution

// private instance variable representing the message
private \[String]\ savedMsg;

// constructor
public Recorder(\[String initialMsg]\) {
// save the initial message
\[savedMsg = initialMsg;]\
}

// accessor: get back the saved message
\[public]\ String \[playback()]\ {
return \[savedMsg]\;
}

// mutator: replace the saved message
\[
public void record(String newMsg) {
// now the new message is saved (the old one is forgotten)
savedMsg = newMsg;
}
]\

// test client
public static void main(String[] args) {
Recorder r = new Recorder("hello");
StdOut.println("The recorded message is: " + r.playback());
StdOut.println("Let's play it again: " + r.playback());
r.record("bonjour");
StdOut.println("The new message is: " + r.playback());
Recorder card = new Recorder("happy birthday!");
StdOut.println("The new recorder says: " + card.playback());
StdOut.println("The old one still says: " + r.playback());
}

Template / Reference solution

Java test suite
See manual

testMain();

C++ test suite
json list of stdin/args tests
e.g. [{"stdin":"hi", "args":["4", "5"]}, {"stdin":"noargs"}]
to just run once with no input use [{}]

C++ test suite
See manual

Forbidden substrings
json list of strings
e.g. ["for","while"]

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Solution visibility remove
Java imports
json list of importables
e.g. ["java.util.*"]

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Override Java classname
else defaults to
websheet name
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Dependent on other websheets?
json list of websheet names in this folder
e.g. ["DataStructure"]

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Is example?
i.e., just a demo
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Add compiler flag(s)
json list of flags
e.g. ["-Wno-unused-variable"]

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Remove default compiler flag(s)
json list of flags
see default_cppflags
e.g. ["-Wno-write-strings"]

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Property	Value
Description html markup shown to student	Make a short recorder that can store a message to be played back. It should have the following API: <ul> <li><tt>public Recorder(String initialMsg) // create new recorder w/this message initially <li><tt>public String playback() // return the saved message <li><tt>public void record(String newMsg) // save this message instead</tt> </ul>
Epilogue html markup shown when solved	remove
Public permissions	remove
Remarks Comments, history, license, etc.	remove
Engine
Choices json list of string, bool pairs e.g. `[["good", true], ["bad", false]]`
Correct answer
Template / Reference solution	// private instance variable representing the message private \[String]\ savedMsg; // constructor public Recorder(\[String initialMsg]\) { // save the initial message \[savedMsg = initialMsg;]\ } // accessor: get back the saved message \[public]\ String \[playback()]\ { return \[savedMsg]\; } // mutator: replace the saved message \[ public void record(String newMsg) { // now the new message is saved (the old one is forgotten) savedMsg = newMsg; } ]\ // test client public static void main(String[] args) { Recorder r = new Recorder("hello"); StdOut.println("The recorded message is: " + r.playback()); StdOut.println("Let's play it again: " + r.playback()); r.record("bonjour"); StdOut.println("The new message is: " + r.playback()); Recorder card = new Recorder("happy birthday!"); StdOut.println("The new recorder says: " + card.playback()); StdOut.println("The old one still says: " + r.playback()); }
Template / Reference solution
Java test suite See manual	testMain();
C++ test suite json list of stdin/args tests e.g. `[{"stdin":"hi", "args":["4", "5"]}, {"stdin":"noargs"}]` to just run once with no input use `[{}]`
C++ test suite See manual
Forbidden substrings json list of strings e.g. `["for","while"]`	remove
Solution visibility	remove
Java imports json list of importables e.g. `["java.util.*"]`	remove
Override Java classname else defaults to websheet name	remove
Dependent on other websheets? json list of websheet names in this folder e.g. `["DataStructure"]`	remove
Is example? i.e., just a demo	remove
Add compiler flag(s) json list of flags e.g. `["-Wno-unused-variable"]`	remove
Remove default compiler flag(s) json list of flags see default_cppflags e.g. `["-Wno-write-strings"]`	remove

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