如何重写此代码以使用面向对象的编程？

Question

public class stackOverflow
{
    public static void main (String args[])
    {
        int maxNumbers = 100;
        int numbers[] = new int[maxNumbers];
        for (int k = 0; k < numbers.length; k++)
            numbers[k] = getRandom(10,99);
        for (int k = 0; k < numbers.length; k++)
            System.out.print(numbers[k] + "  ");
        System.out.println(); 
    }
    public static int getRandom(int min, int max)
    {
        int range = max - min + 1;
        double rndDouble = Math.random() * range;
        int rndInt = (int) rndDouble + min;
        return rndInt;
    }           
}

提供的程序可以正常工作，但是我写得不是很整洁/专业。 谁能给我一些指导，以指导我如何重写它以实现List类下的面向对象编程？

Answer 1

这可以替代...

class Numbers {
    int maxNumbers;
    int numbers[];
    public Numbers(int maxNumbers) {
        // TODO Auto-generated constructor stub
        this.maxNumbers = maxNumbers;
        this.numbers = new int[maxNumbers];
    }
    public int getRandom(int min, int max) {
        int range = max - min + 1;
        double rndDouble = Math.random() * range;
        int rndInt = (int) rndDouble + min;
        return rndInt;
    } 
}
public class StackOverflow {
    public static void main(String [] args) {
        Numbers numbers = new Numbers(100);
        for (int k = 0; k < numbers.numbers.length; k++)
            numbers.numbers[k] = numbers.getRandom(10,99);
        for (int k = 0; k < numbers.numbers.length; k++)
            System.out.print(numbers.numbers[k] + "  ");
    }
}

或类似的东西

public class StackOverflow {

    static int maxNumbers = 100;
    static int numbers[] = new int[maxNumbers];

    public static void main (String args[]) {
        StackOverflow stackOverflow = new StackOverflow();

        for (int k = 0; k < numbers.length; k++)
            numbers[k] = stackOverflow.getRandom(10,99);
        for (int k = 0; k < numbers.length; k++)
            System.out.print(numbers[k] + "  ");
        System.out.println(); 
    }

    public int getRandom(int min, int max) {
        int range = max - min + 1;
        double rndDouble = Math.random() * range;
        int rndInt = (int) rndDouble + min;
        return rndInt;
    }           
}

朋友，有很多选择。

Answer 2

import java.util.ArrayList;
import java.util.List;    

int maxNumbers = 100;
List<Integer> numbers = new ArrayList<Integer>();
for (int k = 0; k < maxNumbers; k++)
    numbers.add( getRandom(10,99) );

System.out.println(numbers.toString()); 

这是您想要的吗？

Answer 3

用oops编写这种structured linear程序的许多方法。 这是我的版本。

public class stackOverflow
{
    int numbers[];

     public stackOverflow(){   //assuming default constructor will provide a 100 length array
      int maxNumbers = 100;
      this.numbers[]  = new int[maxNumbers];
     }

     public stackOverflow(int length){ //Provide a length according to your need.
         this.numbers[] = new int[length];
     }

    private void fillNumberArrayWithRandomNumber(){
    for (int k = 0; k < this.numbers.length; k++)
            numbers[k] = this.getRandom(10,99);
    }

    private void printAllNumbersInArray(){
           for (int k = 0; k < this.numbers.length; k++)
            System.out.print(numbers[k] + "  ");
        System.out.println(); 
    }

    public static void main (String args[])
    {
        stackOverflow obj1 = new stackOverflow(); //default Constructor will call with array lenth 100
        obj1.fillNumberArrayWithRandomNumber();
        obj1.printAllNumbersInArray();

       stackOverflow obj2 = new stackOverflow(50);  //overloaded Constructor will Call with array length 50
        obj2.fillNumberArrayWithRandomNumber();
        obj2.printAllNumbersInArray();

    }
    public int getRandom(int min, int max)
    {
        int range = max - min + 1;
        double rndDouble = Math.random() * range;
        int rndInt = (int) rndDouble + min;
        return rndInt;
    }           
}

将业务逻辑与另一类分开的另一种方法。 并从别人那里叫它。

public class GenerateRandomNumbers
    {
        int numbers[];

         public GenerateRandomNumbers(){   //assuming default constructor will provide a 100 length array
          int maxNumbers = 100;
          this.numbers[]  = new int[maxNumbers];
         }

         public GenerateRandomNumbers(int length){ //Provide a length according to your need.
             this.numbers[] = new int[length];
         }

        public void fillNumberArrayWithRandomNumber(){
        for (int k = 0; k < this.numbers.length; k++)
                numbers[k] = this.getRandom(10,99);
        }

        public void printAllNumbersInArray(){
               for (int k = 0; k < this.numbers.length; k++)
                System.out.print(numbers[k] + "  ");
            System.out.println(); 
        }

        private int getRandom(int min, int max)
        {
            int range = max - min + 1;
            double rndDouble = Math.random() * range;
            int rndInt = (int) rndDouble + min;
            return rndInt;
        }           
    }

  class stackOverflow {
     public static void main (String args[])
        {
            GenerateRandomNumbers obj1 = new GenerateRandomNumbers(); //default Constructor will call with array lenth 100
            obj1.fillNumberArrayWithRandomNumber();
            obj1.printAllNumbersInArray();

           GenerateRandomNumbers obj2 = new GenerateRandomNumbers(50);  //overloaded Constructor will Call with array length 50
            obj2.fillNumberArrayWithRandomNumber();
            obj2.printAllNumbersInArray();

        }
}

Answer 4

您可以使用Random （和nextInt(int) ），并在Java 8+中使用lambda表达式 。 可能看起来像

int maxNumbers = 100;
int min = 10;
int max = 99;
Random rand = new Random();
List<Integer> al = new ArrayList<>();
IntStream.range(0, maxNumbers).forEach(x -> {
    al.add(rand.nextInt(max - min) + min);
});
al.stream().forEach(x -> {
    System.out.printf("%d%n", x);
});

Answer 5

使用清单：

下面是一个示例类，该类利用对象列表保存每个数字。 您可以使用参数化构造函数声明最大大小，也可以使用将其设置为100的默认构造函数。

setNumbers方法永远不会执行一次以上（通过将大小检查为最大大小），以使列表永远不会大于最大大小。 另外，您可以向setNumbers方法中添加参数，以便可以选择每个随机数介于10至99之间的范围。 getNumbers方法将返回包含所有数字的列表对象。

import java.util.ArrayList;
import java.util.List;

public class Example {

    int maxNumbers;
    List<Object> list = new ArrayList<Object>();

public Example(){
    this.maxNumbers = 100;
}

public Example( int max){
    this.maxNumbers = max;
}

private int getRandom(int min, int max)
{
    int range = max - min + 1;
    double rndDouble = Math.random() * range;
    int rndInt = (int) rndDouble + min;
    return rndInt;
}  

public List<Object> getNumbers(){
    return this.list;
}

public void setNumbers(){

    if (list.size() >= maxNumbers){
        return;
    } 

    for (int k = 0; k < this.maxNumbers; k++)
        this.list.add(getRandom(10,99));


}



}

这是驱动程序类的示例。

public class ExampleDriver
{
    public static void main (String args[])
    {
        //Instantiates the object using the default constructor.
        Example test = new Example();

        //Generates the numbers within the list.
        test.setNumbers();

        //Stores the returned list from getNumbers() to exampleList
        List<Object> exampleList = test.getNumbers();
    }


}

Answer 6

您可以创建自己的RandomList来扩展ArrayList<Integer> ：

public class RandomList extends ArrayList<Integer> {
    private int size;
    private int min;
    private int max;
    public RandomList(int size, int min, int max) {
        super(size);
        this.size = size;
        this.min = min;
        this.max = max;
    }

    /**
     * Populate list with entries between min and max
     */
    public void populate() {
        Random rand = new Random();
        for (int t = 0; t < size; t++) {
            this.add(rand.nextInt(max - min) + min);
        }
    }

    public String toString() {
        StringBuilder sb = new StringBuilder();
        for (Integer i:this) {
            sb.append(i).append(" ");
        }
        return sb.toString();
    }

    public static void main (String [] args) {
        RandomList randomList = new RandomList(100, 10, 99);
        randomList.populate();
        System.out.println(randomList);
    }
}

Answer 7

您可以实现自己的List类。 为此，您应该定义一个Node，一个List类（将包含节点）和一个Service来创建随机数。

该服务将以单例形式表示（无法由任何其他类实例化的类）。

    public class MyRandom {

        private static MyRandom rdn = new MyRandom();

        private MyRandom() {}

        public static MyRandom getInstance() {
            return rdn;
        }

        public int getRandom(int min, int max) {
            int range = max - min + 1;
            double rndDouble = Math.random() * range;
            int rndInt = (int) rndDouble + min;
            return rndInt;
        } 

    }

该节点将仅包含一个值（随机数）和对下一个节点的引用。 这是Node类

    public class MyNode {

        private final int value;
        private MyNode next;

        public MyNode(int value) {
            this.value = value;
            next = null;
        }

        public void setNext(MyNode next) {
            this.next = next;
        }

        public int getValue() {
            return value;
        }

        public MyNode getNext() {
            return next;
        }
    }

List类将包含对根节点的引用，该引用还将负责将新节点添加到列表中。

请记住，您也可以使用泛型。

    public final class MyList {

        private MyNode root;

        public MyList(int maxNumber) {
            for (int i = 0; i < maxNumber; i++) {
                addNode(MyRandom.getInstance().getRandom(0, 99));
            }
        }

        public boolean isEmpty() {
            return root == null;
        }

        public void addNode(int value) {
            if (isEmpty()) {
                root = new MyNode(value);
            } else {
                MyNode aux = root;

                while (aux.getNext() != null)
                    aux = aux.getNext();

                aux.setNext(new MyNode(value));
            }
        }

        public void printList() {
            if (!isEmpty()) {
                MyNode aux = root;
                while (aux.getNext() != null) {
                    System.out.println(aux.getValue());
                    aux = aux.getNext();
                }  
                System.out.println(aux.getValue());
            }
        }

    }

Main必须仅实例化MyList类并调用printList来显示列表。

    public class Main {
        public static void main(String[] args) {
            MyList lista = new MyList(10);
            lista.printList();
        }
    }

希望这对您有所帮助。