I am making a flashcard like app for my high school software project. I am able to store words and their respective translation by writing them to a file, but I was wondering if there was a possible way to read them into a 2d array.
Could I separate them with commas, or some other character?
Additionally would there be a way to link the words and their respective translations. For example if I called word 'x', is there a function to call word 'translated x' if it is in an array?
Thanks heaps!!
You might want to look at Maps. That way you could look up each word by the word itself rather than iterating through an Array. Maps use Key Value pairs. Unfortunately, they are unidirctional (you can't look up a key by it's value). https://docs.oracle.com/javase/7/docs/api/java/util/Map.html
Let's break down the problem a bit.
word and a translationword and the translation in a data structure (@Glen Pierce's suggestion about using a map is a good one)Let's say our file looks like this, we use a comma to delimit the word and the translation (this is also the extent of my Spanish vocabulary):
hello,hola
good,bueno
Now some code, let's read the file into a map.
// a map of word to translation
Map<String, String> wordMap = new HashMap<String, String>();
// a class that can read a file (we wrap the file reader in a buffered reader because it's more efficient to read a file in chunks larger than a single character)
BufferedReader fileReader = new BufferedReader(new FileReader("my-file.txt"));
// a line from the file
String line;
// read lines until we read a line that is null (i.e. no more lines)
while((line = fileReader.getLine()) != null) {
// split the line, returns an array of parts
String[] parts = line.split(",");
// store the parts in meaningful variables
String word = parts[0];
String translation = parts[1];
// now, store the word and the translation in the word map
wordMap.put(word, translation);
}
// close the reader (note: you should do this with a try/finally block so that if you throw an exception, you still close the reader)
fileReader.close();
So now we have a map that has all the words and translations in the file. Given a word, you can retrieve the translation like this:
String word = "hello";
String translation = wordMap.get(word);
System.out.println(word + " translates to " + translation);
Output:
hello translates to hola
I guess the next step is to have the user give you a word and for you to return the correct translation. I'll leave that to you.
word,translation pair, and store that pair in the wordMap. So it only stores one pair per iteration of the loop, but it loops over every line in the file. Does that answer your question?Do you need to store the words in a text file (i.e., do they need to persist), or can you store them in memory? If they need to be written to a text file, try this:
// Create a file
File file = new File("file.txt");
// Initialize a print writer to print to the file
PrintWriter pw = new PrintWriter(file);
Scanner keyboard = new Scanner(System.in);
// Populate
boolean stop = false;
do {
String word;
String translation;
System.out.print("Enter a word: ");
word = keyboard.nextLine().trim() + " ";
if (!word.equals("quit ")) {
pw.print(word);
System.out.print("Enter its translation: ");
translation = keyboard.nextLine().trim();
pw.println(translation);
} else {
stop = true;
}
} while (!stop);
// Close the print writer and write to the file
pw.close();
// Initialize a scanner to read the file
Scanner fileReader = new Scanner(file);
// Initialize a hash table to store the values from the file
Hashtable<String, String> words = new Hashtable<String, String>();
// Add the information from the file to the hash table
while (fileReader.hasNextLine()) {
String line = fileReader.nextLine();
String[] array = line.split(" ");
words.put(array[0], array[1]);
}
// Print the results
System.out.println("Results: ");
words.forEach((k, v) -> System.out.println(k + " " + v));
fileReader.close();
keyboard.close();
Note that I am using a space to separate the word from its translation. You can just as easily use a comma or a semicolon or what have you. Just replace line.split(" ") with line.split(< your separating character here>) and concatenate it to the end of word = keyboard.nextLine().trim().
If you don't need to save the information and just need to collect the user's input, it's even simpler:
Scanner keyboard = new Scanner(System.in);
// Initialize a hash table to store the values from the user
Hashtable<String, String> words = new Hashtable<String, String>();
// Get the input from the user
boolean stop = false;
do {
String word;
String translation;
System.out.print("Enter a word: ");
word = keyboard.nextLine().trim();
if (!word.equals("quit")) {
System.out.print("Enter its translation: ");
translation = keyboard.nextLine().trim();
words.put(word, translation);
} else {
stop = true;
}
} while (!stop);
// Print the results
System.out.println("Results: ");
words.forEach((k, v) -> System.out.println(k + " " + v));
keyboard.close();
