Java Array Simple usage

An array is a set of data with the same data type, Java supports multiple arrays, each basic unit of a one-dimensional array is data of the basic data type, and the two-dimensional array is the one-dimensional array of one-dimensional arrays, and so on, Each base cell of an n-dimensional array is a n-1-dimensional array of n-1 arrays. The following example illustrates the use of a Java array with a one-dimensional array.

1. Array declaration

There are two types of array declarations (the positions of brackets are different):

int arr[];int[] arr2;

2, array initialization

There are two forms of array initialization, as follows (using new or not using new):

intnewint[]{13579};int[] arr2 = {246810};

3. Iterating through an array

The traversal array is available For/foreach, as follows:

     Public Static void Main(string[] args) {intArr[] =New int[]{1,3,5,7,9};int[] arr2 = {2,4,6,8,Ten}; for(inti =0; i < arr.length; ++i) {System. out. print (Arr[i] +"\ T");//1 3 5 7 9} for(intX:ARR2) {System. out. print (x +"\ T");//2 4 6 8}    }

4. Arrays.fill () padding array

Using the static method of the Arrays class requires the import package Java.util.Arrays, which defines a number of overloaded methods.

void Fill (int[] A, int val) fills all
void Fill (int[] A, int fromIndex, int toindex, int val) fills the element of the specified index

        int[] Arr3 =New int[5]; for(intX:ARR3) {System. out. print (x +"\ T");//0 0 0 0 0 all initialized to 0} System. out. println (); Arrays.fill (ARR3,Ten); for(intX:ARR3) {System. out. print (x +"\ T");//10 10 10 10 10 all filled to ten} System. out. println (); Arrays.fill (ARR3,1,3,8); for(intX:ARR3) {System. out. print (x +"\ T");//10 8 8 10 10 Fill the specified index} System. out. println ();

5, Arrays.sort () array sorting

void sort (int[] a) all sorts
void sort (int[] A, int fromIndex, int toindex) Sorts the elements of the specified index

        int[] Arr4 = {3,7,2,1,9}; Arrays.sort (ARR4); for(intX:ARR4) {System. out. print (x +"\ T");//1 2 3 7 9} System. out. println ();int[] Arr5 = {3,7,2,1,9}; Arrays.sort (ARR5,1,3); for(intX:ARR5) {System. out. print (x +"\ T");//3 2 7 1 9} System. out. println ();

6, arrays.copyof () copy array

Int[] CopyOf (int[] original, int newlength) to copy an array, specifying the new array length
Int[] Copyofrange (int[] original, int from, int. to) copy an array, specifying the index of the original array being copied

        int[] Arr6 = {1,2,3,4,5};int[] arr7 = arrays.copyof (ARR6,5);//1 2 3 4 5        int[] Arr8 = Arrays.copyofrange (ARR6,1,3);//2 3         for(intX:ARR7) {System. out. print (x +"\ T"); } System. out. println (); for(intX:ARR8) {System. out. print (x +"\ T"); } System. out. println ();

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Java Array Simple usage