Question

(Random Sentences) Write an application that uses random-number generation to create sentences. Use four arrays of strings called article, noun, verb and preposition. Create a sentence by selecting a word at random from each array in the following order: article, noun, verb, preposition, article and noun. As each word is picked, concatenate it to the previous words in the sentence. The words should be separated by spaces. When the final sentence is output, it should start with a capital letter and end with a period. The application should generate and display 20 sentences. The article array should contain the articles "the", "a", "one", "some" and "any"; the noun array should contain the nouns "boy", "girl", "dog", "town" and "car"; the verb array should contain the verbs "drove", "jumped", "ran", "walked" and "skipped"; the preposition array should contain the prepositions "to", "from", "over", "under" and "on".

Short answer

Create arrays for articles, nouns, verbs, and prepositions. Generate 20 sentences in a loop by randomly picking and concatenating elements from each array, capitalizing and punctuating the result.

Step-by-step solution

Define the Arrays

Create four arrays with the following elements. For articles: ['the', 'a', 'one', 'some', 'any']. For nouns: ['boy', 'girl', 'dog', 'town', 'car']. For verbs: ['drove', 'jumped', 'ran', 'walked', 'skipped']. And for prepositions: ['to', 'from', 'over', 'under', 'on'].

Sentence Construction Loop

Set up a loop that will run 20 times to create 20 random sentences. For each iteration, a new sentence will be constructed.

Random Word Selection

Within the loop, randomly select one word from each array. Use a random number generator that selects an index from 0 to the length of the array minus one. Concatenate the selected words in the order of article, noun, verb, preposition, article, noun to form a sentence.

Capitalize and Punctuate

Capitalize the first letter of the constructed sentence and add a period at the end to complete the sentence.

Display the Sentence

Output the finalized sentence and then proceed to the next iteration until 20 sentences have been created and displayed.

Key concepts

Java programming

Java is a widely-used object-oriented programming language that is designed to have as few implementation dependencies as possible. It allows developers to write code that can run on all platforms that support Java without the need for recompilation. The language is known for its robustness, security, and portability.

When working with Java, one typically starts with an idea, such as generating random sentences, and translates that concept into a structured set of instructions known as code. The Java environment includes development tools like compilers, debuggers, and editors, which help transform these instructions into executable applications.

Arrays in Java

Arrays in Java are used to store multiple values in a single variable, instead of declaring separate variables for each value. To declare an array, you specify the type of data it will hold (e.g., String[], int[]) followed by square brackets. Arrays are zero-indexed, meaning the first element's index is 0, which is an important concept when randomly selecting elements, as shown in our random sentence exercise.

One common operation performed on arrays is iterating over them, often done using loops, allowing us to perform actions like constructing sentences from individual words stored in separate arrays.

Random number generation

Random number generation is a feature that allows programmers to create unpredictable outputs such as lottery numbers, random colors for a design application, or, as in our case, words for random sentence creation. In Java, this can be accomplished using the Random class or the Math.random() method.

The Random class provides a way to generate pseudo-random numbers of different types, such as integers, doubles, booleans, etc. The Math.random() method returns a double value greater than or equal to 0.0 and less than 1.0. Conversion of these random values to a range that indexes an array is a crucial step in selecting a random array element.

String manipulation in Java

String manipulation in Java involves various operations that can be performed on strings such as concatenation, comparison, and case conversion. Strings in Java are objects that are immutable, which means once a string is created, it cannot be changed.

For random sentence generation, string concatenation is the primary operation, where individual words are combined to form a sentence. This is done using the + operator or a StringBuilder. The choice between these methods will depend on the specific needs of the program. String manipulation also includes capitalizing the first letter of a sentence, ensuring that a sentence starts with a capital and ends with a period, which enhances the readability of the output.