maximum element in the string of a two-dimensional java array [closed]

Let's localize the problem. Since the question is about finding the maximum element in a two-dimensional array, then we’ll focus on that.

 public static int getMax(int[][] arr) { if (arr.length == 0) throw new IllegalArgumentException(); // пустой массив, кидаем исключение // случай для всех пустых вложенных массивов не рассматриваю. int result = Integer.MIN_VALUE; for (int[] i : arr) { for (int j : i) result = Math.max(result, j); } return result; } 

And the test for this method:

 public static void main(String[] args) { int[][] arr = {{10,20,30}, {5,7,8,99,14}, {}, {91}}; System.out.println(getMax(arr)); } 

Result:

 99 

PS: Try to divide the big task into several small ones. In one method, you define and fill two arrays, search for the maximum in both and then output to the screen. All in one heap. Think over several specialized methods for each of the tasks and implement them. Such code is easier to debug and maintain.

If I understood correctly, then the problem arose when displaying the maximum value of the element of a two-dimensional array? Here is the working version:

 package untitled; import java.io.*; public class Main{ public static void main(String[] args) throws java.io.IOException { int n = 5, max = 0, m = 6, maxb = 0, nn = 3, cn = 8; int[] a = new int[n]; //создание одномерного массива System.out.println("Одномерный массив:"); for (int i = 0; i < a.length; i++) { //заполнение массива случайными числами в интервале [-7; 5] a[i] = (int) Math.round((Math.random() * 13) - 7); System.out.print(a[i] + " "); } for (int i = 0; i < a.length; i++) { if (max < a[i]){ max = a[i]; } } System.out.println(" "); System.out.println("Максимальный элемент одномерного массива " + max); int[][] b = new int[n][m]; System.out.println("Двумерный массив:"); for (int i = 0; i < b.length; i++) { for(int j = 0; j < b[i].length; j++) { b[i][j] = a[i] >> j; System.out.format("%4d", b[i][j]); } System.out.println(); } for (int i = 0; i < b.length; i++) { for(int j = 0; j < b[i].length; j++) { if (maxb < b[i][j]){ maxb = b[i][j]; } } } System.out.println("Максимальный элемент двумерного массива " + maxb); int c [][] = new int[nn][cn]; System.out.println("Нерегулярный массив:"); for(int i = 0; i < c.length; i++){ for(int j = 0; j < c[i].length; j++){ c[i][j] = 3 * i + j + maxb; System.out.format("%4d", c[i][j]); } System.out.println(); } } } 

The result was in the form:

 Одномерный массив: -1 -5 1 6 2 Максимальный элемент одномерного массива 6 Двумерный массив: -1 -1 -1 -1 -1 -1 -5 -3 -2 -1 -1 -1 1 0 0 0 0 0 6 3 1 0 0 0 2 1 0 0 0 0 Максимальный элемент двумерного массива 6 Нерегулярный массив: 6 7 8 9 10 11 12 13 9 10 11 12 13 14 15 16 12 13 14 15 16 17 18 19 

UPDATE

The problem was with the following code snippet

  for(int i = 0; i<b.length; i++){ for(int j = 0; j<b[i].length; j++){ if (b[i][maxb] < b[i][j]){ maxb=j; } } } 

Namely, an error was made in the condition if (b[i][maxb] < b[i][j]) and the action performed under the condition. Based on the task of these cycles, namely the search for the maximum value of the element of a two-dimensional array, it is necessary to determine which number will be greater from the original maxb=0; for use in the following cycles. As a consequence of the error in the condition, the variable maxb remained always equal to zero, which led to a further execution error of the algorithm.

The problem was solved by correcting the condition in the given code fragment, as well as the action performed in case the condition is true.

  for (int i = 0; i < b.length; i++) { for(int j = 0; j < b[i].length; j++) { if (maxb < b[i][j]){ maxb = b[i][j]; } } } System.out.println("Максимальный элемент двумерного массива " + maxb); 

In this fragment, we compare the value of the variable maxb with the value of the element of a two-dimensional array. If the maxb value maxb less than the value of the array element, then this value is assigned to the maxb variable.

I tried to make a universal solution for the multidimensional case. I think it turned out not much started:

 @SuppressWarnings("unchecked") private static <R, E extends Comparable<? super E>> E getMax(R[] array) { Comparator<E> comparator = (e1, e2) -> e1 == null ? (e2 == null ? 0 : -1) : (e2 == null ? 1 : e1.compareTo(e2)); E result = null; for (R e : array) if (e.getClass().isArray()) { E localMax = getMax((R[]) e); result = comparator.compare(localMax, result) > 0 ? localMax : result; } else result = comparator.compare((E) e, result) > 0 ? (E) e : result; return result; } public static void main(String[] args){ Integer[] a1 = new Integer[]{1, 0, 10, 100, 4, 19}; Integer r1 = getMax(a1); System.out.println(r1); Integer[] a2 = new Integer[]{19, 199191, 999, -1, 10}; Integer[][] a3 = new Integer[][]{a1, a2}; Integer r2 = getMax(a3); System.out.println(r2); Integer[][] a4 = new Integer[][]{new Integer[]{1, 202, 2000, 1000000}, a1}; Integer[][][] a5 = new Integer[][][]{a3, a4}; Integer r3 = getMax(a5); System.out.println(r3); }