Java Basic Knowledge Hardening Collection Framework Note 35:list exercise generates random numbers between 10 1~20 (requires: Random numbers cannot be duplicated)

1. Requirements: Get 10 random numbers between 1-20 and require no repetition

An array is implemented, but the length of the array is fixed and the length is not OK.
So we use a collection implementation.

Analysis:
　　• Create an object that produces a random number
• 　　 Create a collection that stores random numbers.
• 　　 define a statistical variable. Starting from 0.
• 　　 Determine if the statistical traversal is less than 10
is: A random number is generated to determine whether the random number exists in the collection.
If it does not exist: Add, Statistics variable + +.
If there is: do not respond to it.
No: Ignore it.
• iterating through the collection

2. Code implementation:

1  Packagecn.itcast_02;2 3 Importjava.util.ArrayList;4 ImportJava.util.Random;5 6 /*7 * Get a random number between 10 and 1-20, which requires no repetition8  * 9 * Implemented with an array, but the length of the array is fixed and the length is not OK. Ten * So we use the set implementation.  One  *  A * Analysis: - * A: Create an object that produces a random number - * B: Create a collection that stores random numbers.  the * C: Define a statistical variable. Starting from 0.  - * D: Determine if the statistical traversal is less than ten - * Yes: A random number is first generated to determine if the random number exists in the collection.  - * If not present: Add, Statistics variable + +.  + * If there is: do not respond to it.  - * No: Ignore it + * E: Traversing the collection A  */ at  Public classRandomdemo { -      Public Static voidMain (string[] args) { -         //create an object that produces a random number -Random r =NewRandom (); -  -         //creates a collection that stores random numbers.  inarraylist<integer> array =NewArraylist<integer>(); -  to         //defines a statistic variable. Starting from 0.  +         intCount = 0; -  the         //determine if the statistical traversal is less than ten *          while(Count < 10) { $             //generate a random number firstPanax Notoginseng             intNumber = R.nextint (20) + 1; -              the             //determines whether the random number exists in the collection.  +             if(!array.contains (number)) { A                 //If it does not exist: Add, Statistics variable + +.  the Array.add (number); +count++; -             } $         } $          -         //iterating through the collection -          for(Integer i:array) { the System.out.println (i); -         }Wuyi     } the}

The results are as follows:

Java Basic Knowledge Hardening Collection Framework Note 35:list exercise generates random numbers between 10 1~20 (requires: Random numbers cannot be duplicated)