Well off with you to learn JAVA -------- array introduction, java -------- Array

Well off with you to learn JAVA -------- array introduction, java -------- Array

Today, I will share with you an important data type in JAVA learning-array.

To store a series of related data, using arrays is a good choice. In addition, if a program fragment often appears repeatedly, defining it as a method can effectively simplify the program code. An array is a data type composed of a group of variables of the same type. They are represented by a common name, and individual elements in the array are marked to indicate their locations.

To use an array of Java, two steps must be taken: (1) declaring the array and (2) Allocating the memory to the array.

The syntax for these two steps is as follows:

The above is a brief introduction to arrays. in JAVA programming, arrays are often used, especially the memory allocation space of arrays, which may not be very understandable at the beginning, I will continue to share with you some examples of arrays in the future.

 

How to Write shuffle programs using java arrays? I just learned java. I 'd like to give you more advice,

Package xly04;
Import java. util. Random;
Public class ArrayDemo3 {
/**
* Array application:
* 1 random shuffling
* 2 sequential Licensing
*/
Public static void main (String [] args ){
String [] cards = new String [] {"Black peach a", "Black peach 2", "Black peach 3", "Black peach 4 ",
"Black peach 5", "Black peach 6", "Black peach 7", "Black peach 8", "Black peach 9", "Black peach 10", "Black peach J", "Black peach Q ", "Black peach K ",
"Hongtao a", "Hongtao 2", "Hongtao 3", "Hongtao 4", "Hongtao 5", "Hongtao 6", "Hongtao 7", "Hongtao 8 ", "Hongtao 9 ",
"Peach 10", "Peach J", "Peach Q", "Peach K", "square A", "square 2", "square 3", "Square 4 ", "block 5 ",
"Square 6", "square 7", "square 8", "square 9", "square 10", "square J", "square q", "square K ", "plum blossom ",
"Plum Blossom 2", "Plum Blossom 3", "Plum Blossom 4", "Plum Blossom 5", "Plum Blossom 6", "Plum Blossom 7", "Plum Blossom 8", "Plum Blossom 9 ", "Plum Blossom 10 ",
"Plum Blossom J", "Plum Blossom Q", "Plum Blossom K", "King", "King "};
// Random random = new Random (); ...... (1)
// Int index = random. nextInt (10); // [0, 10) % 10
// System. out. println (index );
// String card = cards [random. nextInt (cards. length)]; // The length is 8 and the random subscript is [0, 8)
// System. out. println (card); // random card
For (int I = cards. length-1; I> = 1; I --){
Int j = new Random (). nextInt (I); // or (1) do not deregister int j = random. nextInt (I );
... The remaining full text>

Array problems in JAVA

The second problem is that Java cannot directly provide syntax support, but we can continue to implement it.

When you save data, you still use a common array and use letters as subscripts to convert letters into numbers. There are many conversion methods, such:

Private static int [] data = {123,456,789 };
Public static int get (char pos)
{
Return data [Character. toLowerCase (pos)-'a'];
}
Use System. out. println (get ('B'); to check the output.

Java. util. Map and other related classes are required for more complex replacements. For example: "A"-> first, "B"-> second, "C"-> third.
Private static int [] data = {123,456,789 };
Private static Map <String, Integer> posMap = new HashMap <String, Integer> ();
Static
{
PosMap. put ("A", 0 );
PosMap. put ("B", 1 );
PosMap. put ("C", 2 );
}
Public static int get (String pos)
{
Return data [posMap. get (pos)];
}
Use System. out. println (get ("C"); to check the output.