java array of learning

--- for and foreach loop through the array

1 int[][] A = {{2,4},{3,5}};
2 int i = 0;
3 for (int[] is : A) {
4     i++;
5     int j = 0;
6     for (int jl : is) {
7         System.out.print(jl + " ");
8     }
9 }//输出2 4 3 5

Alternatively filled array elements --- Fill ()

. 1  int [] A = {2,4,3,5 };
 2 Arrays.fill (A,. 4); // Output 4444, all array elements are replaced 
. 3 Arrays.fill (A, 0, 2,. 9 ); // output 9935, replacement of the designated index element

Sorting an array --- sort ()

1 int[] A = {2,4,3,5};
2 Arrays.sort(A);//2 3 4 5
3 
4 int[] A = {5,2,4,3,5};
5 Arrays.sort(A, 0, 3);//2 4 5 3 5

Copy the array --- copyOf (), copyOfRange ()

1 int[] A = {5,2,4,3,5};
2 int[] B = Arrays.copyOf(A, 3);//5 2 4
3 int[] B = Arrays.copyOf(A, 7);//5 2 4 3 5 0 0
4 int[] B = Arrays.copyOfRange(A, 2, 5);//4 3 5
5 int[] B = Arrays.copyOfRange(A, 2, 7);//4 3 5 0 0

An array of query --- Arrays.binarySearch ([], key);