带数组/字符串的建议，随机

Question

I am trying to read from a external file. I have successfully done reading from the file, but now I have a little problem. The file contains around 88 verbs. The verbs are written in the file like this: be was been beat beat beaten become became become and so on...

What I need now is that I want a quiz like program where only two random strings from the verb will come up and the user have to fill in the one which is missing. Instead of the one missing, I want this("------") . My english is not so good. So I hope you understand what I mean.

    System.out.println("Welcome to the programe which will test you in english verbs!");
System.out.println("You can choose to be tested in up to 88.");
System.out.println("In the end of the programe you will get a percentage of total right answers.");

Scanner in = new Scanner(System.in);
System.out.println("Do you want to try??yes/no");

String a = in.nextLine();
if (a.equals("yes")) {
    System.out.println("Please enter the name of the file you want to choose: ");

} else {
    System.out.println("Programe is ended!");
}



String b = in.nextLine();
while(!b.equals("verb.txt")){
    System.out.println("You entered wrong name, please try again!");
     b = in.nextLine();

}
System.out.println("How many verbs do you want to be tested in?: ");
int totalVerb = in.nextInt();
in.nextLine();


String filename = "verb.txt";
File textFile = new File(filename);
Scanner input = new Scanner(textFile);

for (int i = 1; i <= totalVerb; i++){



    String line = input.nextLine();

    System.out.println(line);
    System.out.println("Please fill inn the missing verb: ");
    in.next();
}

System.out.println("Please enter your name: ");
in.next();

Answer 1

I don't quite understand what the "problem" is. I assume you can read the file properly, so I won't be commenting on that code. On regards on how to show the verb and for the user to fill in the correct one, you could go with something like this:

1. Read the three verbs
2. Place the three verbs in a String[] array or in an ArrayList
3. Print array[0] + "----" + array[2]
4. Loop for input
5. compare if input is equals to array[1]
6. if it is equals break from the loop and go onto the next three verbs

Hope this pseudocode helps.

Update

On step 3 I mean the following:

String[] conjugations = new String[3];
//You have added the conjugations to this array with conjugations[position]=conjugation;
System.out.println(conjugations[0] + " ----- " + conjugations[2]);

Assuming of course the following:

• You have created your String[] conjugations
• You have read the three conjugations of a verb from the file
• You have placed every conjugation inside your conjugations array

What does this also assume?

• That all the verbs you are testing always have 3 conjugations only and you are always testing for the same tense conjugation (the one that goes in position 1 of the array.)

If you wanted it to be complete random (either of the three conjugations) then you'd need to use the java.util.Random class, as follows:

The following assumes that you have introduced the three conjugations of the verb "beat" into your conjugations String array (String[] conjugations).

Random r = new Random();    
int posOfConjugationToGuess = r.nextInt(conjugations.length);    
String phrase = "";    
String conjugationToGuess;

for(int i=0; i<conjugations.length;++i){
    if(i==posOfConjugationToGuess){
       conjugationToGuess=conjugations[i];
       phrase+=" ----- ";    
    }    
    else{
       phrase+=" " + conjugations[i] + " ";  
    }   
}   
System.out.println(phrase)

;

And when the user inputs something, you'll check it agains conjugationToGuess . I'll explain a bit of the code now.

 Random r = new Random();
int posOfConjugationToGuess = r.nextInt(conjugations.length);

This code allows you to get a random number between 0 (inclusive) and whatever you pass through its constructor ( exclusive ). In this case it will be 3, because that's the length of your conjugations array.

Why did I put this? Well if you were to put, let's say 4, then at some point you'll get the random integer 3, and when you try to do conjugations[3] you'll get an IndexOutOfBoundsError .

The for loop is simply used to construct the phrase to print. How? The idea is that you'll iterate through your conjugations array adding every word to the phrase, but if you come upon the random position (when i==posOfConjugationToGuess ) that determines the conjugation you are asking for, you don't add it to the phrase, but instead put in "------". That's all.

Once again, this assumes that all your verbs only have three conjugations . If the conjugations are not always three, then you'll need to use an ArrayList. Hope this helps.

Answer 2

An easy way to do this would be to implement it like this:

Firstly, read the three verbs from the text file into an String Array[] of size 3. Then use Java.util.Random to generate an int i from 0-2 using the nextInt(int N) method. If, for example, int i was randomly chosen to be 1, you would use a switch or similar if/else structure to display the contents of the array[0] and array[2], then ask for input user input for the missing verb tense. Compare the user input to the contents of the non-displayed array (in this case, array[1]), and return whether it matches.

You should also probably normalize your user input by putting it to all lowercase (using .toLowerCase()) so that users don't get the answer wrong because of case.

Answer 3

First, you need to read all the data from the file:

String[][] verbs = new String[30][3]; //create a new 2D array
Scnanner inFile = new Scanner(new File("<file name here>.txt")); //create a new Scanner object to read data in from a file
for(int i = 0; inFile.hasNext(); i++) //while inFile still has data that hasn't been read; increment i
{
    for(int j = 0; j < 3; j++) //loop 3 times
    {
        verbs[i][j] = inFile.next(); //set read data and put it in "verbs"
    }
}

After this, you will have a 2D array containing all the verbs from the file. Each row in the 2D array contains an array with the three verbs that are the same, but different tenses.

You now need to pick and display two random verbs:

Random random = new Random(); //create a new Random object, which we can use to generate random numbers
int row = random.nextInt(verbs.length) //pick a random set of 3 verbs
columnExcluded = random.nextInt(3) //pick a random verb to guess

System.out.print("Here are two verbs: ");

for(int i = 0; i < 3; i++) //loop 3 times
{
    if(i != columnExcluded) //if this verb is not the one that the person should guess
    {
        System.out.print(verbs[row][i] + ", "); //println the verb
    }
}
System.out.println("_____"); //print blank line
System.out.print("What is the third tense of this verb? ");
String verbGuess = in.nextLine(); //take the guess
if(verbGuess.equalsIgnoreCase(verbs[row][columnExcluded]) //if verb guessed equals the missing verb
{
    System.out.println("You are right!");
}
else
{
    System.out.println("You are wrong. D:");
}