import java.util.Arrays;

public class Main {
    public static void main(String[] args) {
        int[] a = new int[4];                  // all zeros
        int[] b = {5, 3, 9};                   // array initializer
        String[] names = new String[2];        // all null
        boolean[] flags = new boolean[2];      // all false
        double[] d = new double[]{1.5, 2.5};

        a[0] = 42;
        System.out.println(Arrays.toString(a) + " len=" + a.length);
        System.out.println(Arrays.toString(b) + " " + Arrays.toString(names) + " " + Arrays.toString(flags) + " " + Arrays.toString(d));
        System.out.println(b);                 // prints type@hash — not the contents!
    }
}

import java.util.Arrays;

public class Main {
    public static void main(String[] args) {
        int[][] grid = new int[2][3];          // 2 rows × 3 columns
        grid[1][2] = 7;
        System.out.println(Arrays.deepToString(grid));

        int[][] jagged = new int[3][];         // rows created separately
        for (int i = 0; i < jagged.length; i++) {
            jagged[i] = new int[i + 1];
            Arrays.fill(jagged[i], i);
        }
        System.out.println(Arrays.deepToString(jagged));

        int[][] m = {{1, 2}, {3, 4}};
        int total = 0;
        for (int[] row : m) for (int x : row) total += x;
        System.out.println("total=" + total + " rows=" + m.length + " cols=" + m[0].length);
    }
}

[[0, 0, 0], [0, 0, 7]]
[[0], [1, 1], [2, 2, 2]]
total=10 rows=2 cols=2

import java.util.Arrays;

public class Main {
    public static void main(String[] args) {
        int[] a = {5, 2, 8, 1, 9};
        Arrays.sort(a);                                        // dual-pivot quicksort for primitives
        System.out.println(Arrays.toString(a));
        System.out.println(Arrays.binarySearch(a, 8));         // array must be sorted
        int[] bigger = Arrays.copyOf(a, 7);                    // pads with zeros
        int[] mid = Arrays.copyOfRange(a, 1, 3);
        System.out.println(Arrays.toString(bigger) + " " + Arrays.toString(mid));

        int[] x = {1, 2}, y = {1, 2};
        System.out.println((x == y) + " " + x.equals(y) + " " + Arrays.equals(x, y));

        Integer[] boxed = {3, 1, 2};
        Arrays.sort(boxed, (p, q) -> q - p);                   // comparator needs objects
        System.out.println(Arrays.toString(boxed));
        System.out.println(Arrays.stream(a).sum() + " " + Arrays.stream(a).max().getAsInt());
    }
}

[1, 2, 5, 8, 9]
3
[1, 2, 5, 8, 9, 0, 0] [2, 5]
false false true
[3, 2, 1]
25 9

import java.util.*;

public class Main {
    public static void main(String[] args) {
        String[] arr = {"a", "b", "c"};
        List<String> view = Arrays.asList(arr);     // fixed-size view backed by arr
        view.set(0, "z");
        System.out.println(arr[0]);                  // the array changed too
        try {
            view.add("d");
        } catch (UnsupportedOperationException e) {
            System.out.println("cannot add: " + e.getClass().getSimpleName());
        }

        int[] prim = {1, 2, 3};
        System.out.println(Arrays.asList(prim).size());   // List<int[]> with ONE element
        List<String> copy = new ArrayList<>(Arrays.asList(arr));   // real, growable list
        copy.add("d");
        System.out.println(copy);
    }
}

z
cannot add: UnsupportedOperationException
1
[z, b, c, d]

public class Main {
    public static void main(String[] args) {
        Object[] objs = new String[2];      // compiles: String[] is an Object[]
        objs[0] = "fine";
        try {
            objs[1] = 42;                   // runtime check fails
        } catch (ArrayStoreException e) {
            System.out.println("ArrayStoreException: " + e.getMessage());
        }
    }
}

ArrayStoreException: java.lang.Integer