Question

我目前正在使用一个程序，每次运行程序时都会实例化三个数字变量。例如：

(companyID, groupID, hostID)

The 1st time when I run it
(int companyID = 1; int groupID = 1, int hostID = 1)

2nd time
(1, 1, 1)

3rd time
(1, 1, 1)

4th
(1, 2, 1)

5th
(6, 4, 3)

...

有没有一种方法可以在每次运行程序时保存数据集中的三个数字，同时防止以相同顺序重复的数字存储在数据集中？在上面的示例中，仅存储1,1,1的一个实例。

因此，存储在数据集中的最终结果仅为（1,1,1），（1,2,1），（6,4,3）。

感谢。

Answer 1

试试这个：

<强> CODE

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

public class DatasetUnique {

    public static void main(String args[]){

        //  Data to insert
        int[] one =     {1,2,3};
        int[] two =     {2,3,4};
        int[] three =   {1,2,3};
        int[] four =    {7,8,9};
        int[] five =    {2,3,4};

        //  Data inserted
        List<dataSet> allContent = new ArrayList<>();

        //  1 - Insert data
        insert(new dataSet(one), allContent);
        insert(new dataSet(two), allContent);
        insert(new dataSet(three), allContent);
        insert(new dataSet(four), allContent);
        insert(new dataSet(five), allContent);

        //  2 - Print data
        System.out.println(allContent.toString());

    }

    //  Insert a dataset inside list if doesnt exists
    private static void insert(dataSet dataSetToInsert, List<dataSet> allContent){
        if(allContent.size() == 0){
            allContent.add(dataSetToInsert);
        }else{
            for(dataSet ds: allContent){
                if(dataSetToInsert.equals(ds)){
                    return;
                }               
            }
            allContent.add(dataSetToInsert);
        }
    }

    //  Class for each dataSet
    private static class dataSet{

        int firstNumber;
        int secondNumber;
        int thirdNumber;

        public dataSet(int[] dataSet) {
            super();
            this.firstNumber = dataSet[0];
            this.secondNumber = dataSet[1];
            this.thirdNumber = dataSet[2];
        }

        @Override
        public boolean equals(Object obj) {
            if (this == obj)
                return true;
            if (obj == null)
                return false;
            if (getClass() != obj.getClass())
                return false;
            dataSet other = (dataSet) obj;          
            if (firstNumber != other.firstNumber)
                return false;
            if (secondNumber != other.secondNumber)
                return false;
            if (thirdNumber != other.thirdNumber)
                return false;
            return true;
        }

        @Override
        public String toString() {
            return "\n" + firstNumber + " " + secondNumber + " "+ thirdNumber + "\n";
        }       
    }


}

<强>输出

Answer 2

你需要一些包装类。您可以存储3个整数或一组整数，这取决于您。您需要实现Comparable接口如果您将使用Set类来完成此任务，请注意HashSet将不起作用，因为它不是基于自然顺序。 TreeSet会。这是您的类的简单代码示例。

当然，这不包括将类存储在文件中的部分，但允许您在工作时管理重复项。然后你可以将所有元素从set写入文件，它们将是唯一的。并从文件加载元素以便在开始时设置。

import java.util.Set;
import java.util.TreeSet;

public class Test {
    public static final class Tuple implements Comparable<Tuple> {
        public int x1;
        public int x2;
        public int x3;

        public Tuple(int x1, int x2, int x3) {
            this.x1 = x1;
            this.x2 = x2;
            this.x3 = x3;
        }

        /**
         * You don't need equal method to work with sets (and this is not even overriding basic equals method,
         * but it's just an example of how you can easily compare your tuples
         */
        public boolean equals(Tuple obj) {
            return this.x1 == obj.x1 && this.x2 == obj.x2 && this.x3 == obj.x3;
        }

        /**
         * Check javadoc for this, but it's just a way to tell if one tuple is more, equal or less then another
         */
        @Override
        public int compareTo(Tuple o) {
            if (o.x1 != this.x1) {
                return new Integer(o.x1).compareTo(this.x1);
            }
            if (o.x2 != this.x2) {
                return new Integer(o.x2).compareTo(this.x2);
            }
            return new Integer(o.x3).compareTo(this.x3);
        }

        @Override
        public String toString() {
            return "[" + x1 + " " + x2 + " " + x3 + "]";
        }
    }

    public static void main(String[] args) {
        /**
         * Note, that HashSet won't work because it doesn't depend on natural ordering of elements.
         * TreeSet does, and it will work fine for your purpose.
         */
        Set<Tuple> tuples = new TreeSet<>();
        tuples.add(new Tuple(1, 1, 1));
        tuples.add(new Tuple(1, 2, 3));
        tuples.add(new Tuple(1, 1, 1));
        tuples.add(new Tuple(2, 3, 4));
        tuples.add(new Tuple(2, 3, 4));
        tuples.add(new Tuple(1, 2, 3));

        for (Tuple tuple: tuples) {
            System.out.println(tuple);
        }
    }
}`

这将是

的输出

[2 3 4]
[1 2 3]
[1 1 1]

没有重复项放入Set。

使用Java中的多个字段防止重复的日期集

2 个答案: