import java.util.*;

public class Main {
    public static void main(String[] args) {
        List<Integer> xs = new ArrayList<>(List.of(5, 3, 9, 1, 3));
        Collections.sort(xs);
        System.out.println(xs + " binarySearch(5)=" + Collections.binarySearch(xs, 5)
                + " binarySearch(4)=" + Collections.binarySearch(xs, 4));
        Collections.reverse(xs);
        System.out.println(xs + " max=" + Collections.max(xs) + " min=" + Collections.min(xs));
        System.out.println("frequency(3)=" + Collections.frequency(xs, 3));
        Collections.swap(xs, 0, 4);
        System.out.println(xs);
        Collections.rotate(xs, 1);
        System.out.println(xs);
        Collections.shuffle(xs, new Random(42));   // seeded -> reproducible
        System.out.println(xs);
        System.out.println(Collections.nCopies(3, "ab") + " " + String.join("", Collections.nCopies(3, "-")));
        System.out.println(Collections.disjoint(List.of(1, 2), List.of(3, 4)));
    }
}

[1, 3, 3, 5, 9] binarySearch(5)=3 binarySearch(4)=-4
[9, 5, 3, 3, 1] max=9 min=1
frequency(3)=2
[1, 5, 3, 3, 9]
[9, 1, 5, 3, 3]
[1, 5, 3, 3, 9]
[ab, ab, ab] ---
true

import java.util.*;

public class Main {
    public static void main(String[] args) {
        List<String> src = new ArrayList<>(List.of("a"));
        List<String> view = Collections.unmodifiableList(src);
        List<String> copy = List.copyOf(src);
        src.add("b");
        System.out.println(view + " " + copy);   // the view sees the change, the copy doesn't
        try {
            view.add("c");
        } catch (UnsupportedOperationException e) {
            System.out.println("view is read-only");
        }
    }
}

[a, b] [a]
view is read-only

import java.util.*;

public class Main {
    public static void main(String[] args) {
        int[] a = {5, 2, 8, 1};
        Arrays.sort(a);
        System.out.println(Arrays.toString(a) + " idx(5)=" + Arrays.binarySearch(a, 5));

        int[] filled = new int[4];
        Arrays.fill(filled, -1);
        System.out.println(Arrays.toString(filled));

        int[] bigger = Arrays.copyOf(a, 6);            // pads with 0
        int[] slice = Arrays.copyOfRange(a, 1, 3);     // [1, 3)
        System.out.println(Arrays.toString(bigger) + " " + Arrays.toString(slice));

        System.out.println(Arrays.stream(a).sum() + " " + Arrays.stream(a).max().getAsInt());
        System.out.println(Arrays.equals(a, new int[]{1, 2, 5, 8}) + " " + (a == a.clone()));

        int[][] grid = {{1, 2}, {3, 4}};
        System.out.println(Arrays.deepToString(grid));

        Integer[] boxed = {3, 1, 2};
        Arrays.sort(boxed, Collections.reverseOrder()); // comparators need object arrays
        System.out.println(Arrays.toString(boxed));
    }
}

[1, 2, 5, 8] idx(5)=2
[-1, -1, -1, -1]
[1, 2, 5, 8, 0, 0] [2, 5]
16 8
true false
[[1, 2], [3, 4]]
[3, 2, 1]

import java.util.*;

public class Main {
    public static void main(String[] args) {
        String[] arr = {"x", "y", "z"};
        List<String> fixed = Arrays.asList(arr);   // fixed-size view over the array
        fixed.set(0, "X");                          // allowed, writes through
        System.out.println(Arrays.toString(arr));
        try {
            fixed.add("w");
        } catch (UnsupportedOperationException e) {
            System.out.println("add -> UnsupportedOperationException");
        }

        int[] prim = {1, 2, 3};
        System.out.println(Arrays.asList(prim).size());      // List<int[]> with ONE element
        System.out.println(Arrays.asList(1, 2, 3).size());   // varargs of Integer

        List<String> growable = new ArrayList<>(Arrays.asList(arr));
        growable.add("w");
        System.out.println(growable);
    }
}

[X, y, z]
add -> UnsupportedOperationException
1
3
[X, y, z, w]