integer arraylist to int array
//only works in java 8 or later
list.stream().mapToInt(i -> i).toArray();integer arraylist to int array
//only works in java 8 or later
list.stream().mapToInt(i -> i).toArray();list to int array in java 8
int[] array = list.stream().mapToInt(i->i).toArray();convert list of integer to array in java
List<Integer> al = new ArrayList<Integer>();
Integer[] arr = new Integer[al.size()];
arr = al.toArray(arr);Java 7. Converting List<List<Integer>> to int
// original list
List<List<Integer>> list = Arrays.asList(
Arrays.asList(1, 2),
Arrays.asList(2),
Arrays.asList(3));
// initialize the array,
// specify only the number of rows
int[][] arr = new int[list.size()][];
// iterate through the array rows
for (int i = 0; i < arr.length; i++) {
// initialize the row of the array,
// specify the number of elements
arr[i] = new int[list.get(i).size()];
// iterate through the elements of the row
for (int j = 0; j < arr[i].length; j++) {
// populate the array
arr[i][j] = list.get(i).get(j);
}
}
// output
System.out.println(Arrays.deepToString(arr));
// [[1, 2], [2], [3]]Copyright © 2021 Codeinu
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