MessageBuilder is #1 from the from the 2025 AP Computer Science A Course Description sample problems.

2025 AP CS A Course Description

The sample free response start on PDF page 168 (labeled page 161 at the bottom right).

Part (a) MessageBuilder constructor

public MessageBuilder(String startingWord)
{
    message = startingWord;
    numWords = 1;

    String nextWord = getNextWord(startingWord);

    while(nextWord != null)
    {
        message += " " + nextWord;
        numWords++;
        nextWord = getNextWord(nextWord);
    }
}

Part (b) getAbbreviation method

public String getAbbreviation()
{
    String abbreviation = "";

    for(String word : message.split(" "))
        abbreviation += word.substring(0, 1);

    return abbreviation;
}

Java files with test code

MessageBuilderTester.java includes JUnit 5 test code with the examples from the problem. See Running JUnit 5 tests. MessageBuilder.java includes a working implementation of getNextWord. The getNextWord implementation throws an exception if passed a word other than the immediately preceeding word in the sequence.

MessageBuilder.java
MessageBuilderTester.java

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