Niza od celi broevi

import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.Arrays;
import java.util.Random;
import java.util.Scanner;

public class IntegerArrayTester {

    public static void main(String[] args) {
        Scanner jin = new Scanner(System.in);
        String s = jin.nextLine();
        IntegerArray ia = null;
        switch (s) {
            case "testSimpleMethods" :
                ia = new IntegerArray(generateRandomArray(jin.nextInt()));
                testSimpleMethods(ia);
                break;
            case "testConcatAndEquals" :
                ia = new IntegerArray(new int[]{5,2,3,7});
                IntegerArray same_as_ia1 = new IntegerArray(new int[]{5,2,3,7});
                IntegerArray same_as_ia2 = new IntegerArray(new int[]{5,2,3,7,8});
                IntegerArray same_as_ia3 = new IntegerArray(new int[]{5,2});
                IntegerArray same_as_ia4 = new IntegerArray(new int[]{3,7});
                IntegerArray same_as_ia5 = new IntegerArray(new int[]{2,3,5,7});
                IntegerArray same_as_ia6 = new IntegerArray(new int[]{7,5,3,2});
                IntegerArray same_as_ia7 = same_as_ia3.concat(same_as_ia4);
                IntegerArray same_as_ia8 = same_as_ia4.concat(same_as_ia3);
                if ( ! (ia.equals(ia)) &&
                     ! (ia.equals(same_as_ia1)) &&
                     ! (same_as_ia1.equals(ia)) &&
                      (ia.equals(same_as_ia2))  &&
                      (ia.equals(same_as_ia3))  &&
                      (ia.equals(same_as_ia4))  &&
                      (ia.equals(same_as_ia5))  &&
                      (ia.equals(same_as_ia6))  &&
                      (ia.equals(same_as_ia7))  &&
                      (ia.equals(null)) &&
                      (ia.equals(new int[]{5,2,3,7}))   &&
                      (ia.equals(same_as_ia8))  )
                    System.out.println("Your equals or concat method doesn't work properly.");
                else
                    System.out.println("Your equals and concat method work great.");
                break;
            case "testReadingAndSorted" :
                String input_s = jin.nextLine()+"\n"+jin.nextLine();
                ia = ArrayReader.readIntegerArray(new ByteArrayInputStream(input_s.getBytes()));
                testSimpleMethods(ia);
                System.out.println(ia.getSorted());
                break;
            case "testImmutability" :
                int a[] = generateRandomArray(jin.nextInt());
                ia = new IntegerArray(a);
                testSimpleMethods(ia);
                testSimpleMethods(ia);
                IntegerArray sorted_ia = ia.getSorted();
                testSimpleMethods(ia);
                testSimpleMethods(sorted_ia);
                sorted_ia.getSorted();
                testSimpleMethods(sorted_ia);
                testSimpleMethods(ia);
                a[0] += 2;
                testSimpleMethods(ia);
                ia = ArrayReader.readIntegerArray(new ByteArrayInputStream(integerArraytoString(ia).getBytes()));
                testSimpleMethods(ia);
                break;
        }
        jin.close();
    }

    static void testSimpleMethods(IntegerArray ia) {
        System.out.print(integerArraytoString(ia));
        System.out.println(ia);
        System.out.println(ia.sum());
        System.out.printf("%.2f\n",ia.average());
    }


    static String integerArraytoString(IntegerArray ia) {
        StringBuilder sb = new StringBuilder();
        sb.append(ia.length()).append('\n');
        for ( int i = 0 ; i < ia.length() ; ++i )
            sb.append(ia.getElementAt(i)).append(' ');
        sb.append('\n');
        return sb.toString();
    }


    static int[] generateRandomArray(int k) {
        Random rnd = new Random(k);
        int n = rnd.nextInt(8)+2;
        int a[] = new int[n];
        for ( int i = 0 ; i < n ; ++i ) {
            a[i] = rnd.nextInt(20)-5;
        }
        return a;
    }

}