Simple, quick and dirty way to generate a random "IN" clause in SQL language.

RandomGenerator.java

/**
 * @author xsalefter ([email protected])
 */
public class RandomGenerator {
	
	private int sizeOfQuestion; // Mean how much question want to display per user.
	private Random random;
	private int dataSize; // This is total amount of data in the database. 
	private StringBuffer generatedRandomNumber;
	
	public RandomGenerator() {
		this.random = new Random();
	}
	
	public RandomGenerator(int sizeOfQuestion) {
		this();
		this.sizeOfQuestion = sizeOfQuestion;
	}
	
	public RandomGenerator(int sizeOfQuestion, int dataSize) {
		this(sizeOfQuestion);
		this.dataSize = dataSize;
	}
	
	public RandomGenerator setDataSize(int dataSize) {
		this.dataSize = dataSize;
		return this;
	}
	
	public RandomGenerator setSizeOfQuestion(int question) {
		this.sizeOfQuestion = question;
		return this;
	}
	
	public RandomGenerator parse() {
		this.generatedRandomNumber = new StringBuffer();
		
		for (int i = 1; i <= this.sizeOfQuestion; i ++) {
			if (i == this.sizeOfQuestion) {
				this.generatedRandomNumber.
					append((this.random.nextInt(dataSize) + 1));
			} else {
				this.generatedRandomNumber.
					append((this.random.nextInt(dataSize) + 1)).
					append(", ");
			}
		}
		return this;
	}
	
	public String generate() {
		return new StringBuffer().
			append("('").
			append(this.generatedRandomNumber.toString()).
			append("')").
			toString();
	}
	
	public String generate(String prefix, String postfix) {
		return new StringBuffer().append(prefix).
			append(this.generatedRandomNumber.toString()).
			append(postfix).
			toString();
	}
}

public class RandomGeneratorTest {

@Test
public void test1() {
    RandomGenerator generator = new RandomGenerator(10);

    String inValue1 = generator.
        setDataSize(100).
        parse().
        generate();

    String inValue2 = generator.
        setDataSize(100).
        parse().
        generate();

    String inValue3 = generator.
        setDataSize(100).
        parse().
        generate("[\"", "\"]");

    System.out.println(inValue1);
    System.out.println(inValue2);
    System.out.println(inValue3);
}

}