Any help or advice would be greatly appreciated. I'm trying to create a simple game which generates ten different, random questions. The questions can contain 2, 3 or 4 integers. So something like this: 55 2 − 4 − 101, 102/3/3, 589 − 281, 123 + 5 6 + 2.
The question will be displayed in a textview and then the user can take a guess, entering values into an edittext and then upon clicking a key on a custom keypad I have created it will check the answer, and then display the next question in the sequence of 10.
I know how to create random numbers, just struggling to work out how to create a whole question with random operators (+, -, /, *).
Big thank you to anyone who has the time to construct a reply.
A little of spare time produced a complete example for your case. Create new RandomMathQuestionGenerator.java file and it is cooked for compilation.
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.Random;
public class RandomMathQuestionGenerator {
private static final int NUMBER_OF_QUESTIONS = 10;
private static final int MIN_QUESTION_ELEMENTS = 2;
private static final int MAX_QUESTION_ELEMENTS = 4;
private static final int MIN_QUESTION_ELEMENT_VALUE = 1;
private static final int MAX_QUESTION_ELEMENT_VALUE = 100;
private final Random randomGenerator = new Random();
public static void main(String[] args) {
RandomMathQuestionGenerator questionGenerator = new RandomMathQuestionGenerator();
List<Question> randomQuestions = questionGenerator.getGeneratedRandomQuestions();
for (Question question : randomQuestions) {
System.out.println(question);
}
}
public List<Question> getGeneratedRandomQuestions() {
List<Question> randomQuestions = new ArrayList<Question>(NUMBER_OF_QUESTIONS);
for (int i = 0; i < NUMBER_OF_QUESTIONS; i++) {
int randomQuestionElementsCapacity = getRandomQuestionElementsCapacity();
Question question = new Question(randomQuestionElementsCapacity);
for (int j = 0; j < randomQuestionElementsCapacity; j++) {
boolean isLastIteration = j + 1 == randomQuestionElementsCapacity;
QuestionElement questionElement = new QuestionElement();
questionElement.setValue(getRandomQuestionElementValue());
questionElement.setOperator(isLastIteration ? null
: Operator.values()[randomGenerator.nextInt(Operator.values().length)]);
question.addElement(questionElement);
}
randomQuestions.add(question);
}
return randomQuestions;
}
private int getRandomQuestionElementsCapacity() {
return getRandomIntegerFromRange(MIN_QUESTION_ELEMENTS, MAX_QUESTION_ELEMENTS);
}
private int getRandomQuestionElementValue() {
return getRandomIntegerFromRange(MIN_QUESTION_ELEMENT_VALUE, MAX_QUESTION_ELEMENT_VALUE);
}
private int getRandomIntegerFromRange(int min, int max) {
return randomGenerator.nextInt(max - min + 1) + min;
}
}
class Question {
private List<QuestionElement> questionElements;
public Question(int sizeOfQuestionElemets) {
questionElements = new ArrayList<QuestionElement>(sizeOfQuestionElemets);
}
public void addElement(QuestionElement questionElement) {
questionElements.add(questionElement);
}
public List<QuestionElement> getElements() {
return questionElements;
}
public int size() {
return questionElements.size();
}
@Override
public String toString() {
StringBuilder sb = new StringBuilder();
for (QuestionElement questionElement : questionElements) {
sb.append(questionElement);
}
return sb.toString().trim();
}
}
class QuestionElement {
private int value;
private Operator operator;
public int getValue() {
return value;
}
public void setValue(int value) {
this.value = value;
}
public Operator getOperator() {
return operator;
}
public void setOperator(Operator operator) {
this.operator = operator;
}
@Override
public String toString() {
return value + (operator == null ? "" : " " + operator.getDisplayValue()) + " ";
}
}
enum Operator {
PLUS("+"), MINUS("-"), MULTIPLIER("*"), DIVIDER("/");
private String displayValue;
private Operator(String displayValue) {
this.displayValue = displayValue;
}
public String getDisplayValue() {
return displayValue;
}
}
Run and preview. Hope this helps.
Thanks to:
- Generating random number in
range
- Retrieving random
element from array
Create an array char[] ops = { '+', '-', '/', '*' } and create a random int i in range [0,3], and chose ops[i]
You will need to take care that you do not generate a divide by zero question.
You can make it even more generic by creating an interface MathOp and creating 4 classes that implement it: Divide, Sum , ... and create an array: MathOp[] ops instead of the char[]
Using this, it will also give you much easier time to check the result later on...
Put your operators in an array (4 elements), generate a random integer from 0 to 3, and pick the operator that is at this index in the array.
Do that each time you need to have a random operator, i.e. after every number of your question except the last one.
Make an array that has one entry for each of the operators. Then generate a random number between 0 and the length of the array minus 1.
So since each operation is binary you can just worry about figuring out the base case and then building up your expressions from there.
An easy way would just to select a random number an correlate that which operation will be used.
int displayAnswer(int leftSide, int rightSide, int operation {
int answer;
string operation;
switch(operation) {
case 1:
operation = "+";
answer = leftSide + rightSide;
break;
case 2:
operation = "-";
answer = leftSide - rightSide;
break;
case 3:
operation = "*";
answer = leftSide * rightSide;
break;
case 4:
operation = "/";
answer = leftSide / rightSide:
break;
}
textView.setText(leftSide + operation + rightSide);
return answer;
}
