What is an array

statement

initialization

Simple data type array (Refer to the memory change chart on PPT)

Reference data type array (Refer to the memory change chart on PPT)

Default initialization rules for array elements

Reference method of array elements: array name [subscript]

for (data type variable name: array variable name) {...}

Purpose: Only suitable for sequentially traversing and displaying the contents of all elements in an array or collection.

Defect: Index (subscript) value cannot be accessed when traversing an array or collection

When declaring a method .....Method name (data type... variable name)

It can accept 0-n parameters of this type. Use arrays in methods to process

Variable parameters must be written at the end of the formal parameter list, Otherwise, a compilation error will be reported.

java class name abc "hello world" 123 "ni hao"

Pass parameters to (String args[]) of the main method

sort

Find

public static void sort(int[] a);

public static int binarySearch(int[] a, int key); //Use binary search method, provided that the array has been sorted from small to large

public static String toString(int [] a) //Format the incoming array into string output

array of arrays

initialization

System.arraycopy(.....)

public static int[] copyOf(int[] original, int newLength) of Arrays class