Java base Array (with base sort method)

An array is a data structure used to store a collection of values of the same type

1. The array needs to declare the array type (that is, the stored data type), such as: int [] A; where int is an array type [] represents a one-dimensional array, a represents the array name.

2. Create an array a:int [] a = new int[100]; Indicates that creating an array that stores 100 integers does not have a specific value when the default is 0.

You can also create an array of specific content directly: int [] A = {1, 2, 3, 4, 5, 6, 7, 8, 9};

the elements of the Boolean array are initialized to false;

The elements of an object array are initialized to a special value of NULL, which means that the elements have not yet held any objects. (For example: for (int i=0;i<100;i++) names[i]= "";

3. Multidimensional array: int [] [] a = new int[10][10]; Represents creating a two-dimensional array of 10*10, and so on.

Example: Using a two-dimensional array to generate a Yang Hui triangle:

1  PackageDemo1;2 ImportJava.util.Scanner;3 4  Public classDemo1 {5      Public Static voidMain (string[] args) {6SYSTEM.OUT.PRINTLN ("Please lose Yang Hui triangle layer");7     //8 9 Row is the get input data input statement8Scanner sc =NewScanner (system.in);9          introw =sc.nextint ();Ten sc.close (); One          int[] m =New int[Row][row]; A           for(inti = 0; i < row; i++) { -               for(intk = 0; K < 8-i; k++) { -                   theSystem.out.print (""); -}//The body of this for statement is the number of spaces to print per line -                 -                   for(intj = 0; J < i + 1; J + +) { +                          if(j = = 0 | | i = =j) { -M[I][J] = 1;//determine the position of the Yang Hui triangle number 1 +}Else { AM[I][J] = M[i-1][j] + m[i-1][j-1]; at                     //find array-specific data contact -                      } -System.out.printf ("%2d", M[i][j]); -                  } -System.out.println ();//Blank Line -          }    in}

Bubble Sort Method:

 PackageDemo1;Importjava.util.Arrays; Public classTest1 { Public Static voidMain (string[] args) {int[] arr = {5, 8, 1, 7, 4, 9, 6, 3, 2}; BooleanFlag =false;//total number of bubbles-1 non-mandatory         for(inti = 0;! Flag && i < arr.length-1; i++) {flag=true;  for(intj = 0; J < arr.length-1-I; J + +) {            //-1 must prevent cross-border reduction I to improve efficiency            if(Arr[j] > arr[j + 1]) {                inttemp =Arr[j]; ARR[J]= Arr[j + 1]; Arr[j+ 1] =temp; //Determine unorderedFlag =false;     }}} System.out.println (Arrays.tostring (arr)); }}

Select the sorting method:

1                   int[] arr = {5, 8, 1, 7, 4, 9, 6, 3, 2};2                    for(inti = 0; i < arr.length-1; i++) {3             //Assuming that the current I address is the location of the sample minimum value4             intnum =i;5              for(intj = i + 1; J < arr.length;j++) {6                 //if the J position element is smaller than the current position element, update the minimum position7                 if(Arr[num] >Arr[j]) {8num =J;9                 }Ten             } One             //swaps the current minimum position element with the first element of the unordered area A             inttemp =Arr[i]; -Arr[i] =Arr[num]; -Arr[num] =temp; the         } -System.out.println (arrays.tostring (arr));

Insert Sort Method:

1          for(inti = 1; i < arr.length; i++) {2             //J Current position to be inserted forward3             intj =i;4             //Save the element to be inserted forward in temp.5             inttemp =Arr[j];6             //temp is less than the previous element of the current position7              while(J > 0 && Temp < arr[j-1]) {//use short-circuit and skip over-bounds8                 //Save the previous element to the current location9ARR[J] = arr[j-1];Ten                 //move forward at current position Onej--; A             } -             //put the required data into the correct position -ARR[J] =temp; the          -         } -System.out.println (arrays.tostring (arr));

Java base Array (with base sort method)