如何从二维 int 数组构造 ArrayList? [英] How to construct ArrayList from 2D int array?

问题描述

我有一个 2D int 数组，例如我想删除重复的行

I have a 2D int array, i want to remove duplicate rows for example

30,40,50

50,30,40

30,40,50

在上面的例子 2nd &第三行与第一行重复.

in above example 2nd & 3rd row is duplicate of 1st row.

我知道 ArrayList 可以动态增长和下沉，这对于这个概念是有用的类，但是我们如何将 int[][] 转换为 ArrayList.

I know ArrayList can dynamically grow and sink which is useful class for this concept but how we convert int[][] into ArrayList.

推荐答案

首先，你应该创建一个类来保存你的数据，这些数据覆盖了 public boolean equals(Object obj) 和 public inthashCode() 表示数据的相等性.

First, you should create a Class to hold you data which override public boolean equals(Object obj) and public int hashCode() to indicate equality of the data.

public class Row {

    private int[] ints;

    public Row(int[] ints) {
        this.ints = ints.clone();
        Arrays.sort(this.ints);
    }

    @Override
    public int hashCode() {
        return Arrays.hashCode(ints);
    }

    @Override
    public boolean equals(Object obj) {

        if(obj instanceof Row) {
            Row another = (Row) obj;
            int[] original = Arrays.copyOf(another.ints, another.ints.length);
            return Arrays.equals(ints, original);
        } else {
            return false;
        }
    }

    @Override
    public String toString() {
        return Arrays.toString(ints);
    }

}

测试用例

public class Test {

    public static void main(String[] args) {
        int[][] arrays = new int[][]{{30,40,50}, {50,30,40}, {30,40,50}, {10, 20, 30}};
        Set<Row> rows = new HashSet<Row>();
        for(int[] a: arrays) {
            rows.add(new Row(a));
        }
        for(Row row: rows) {
            System.out.println(row);
        }
    }
}

输出

[10, 20, 30]
[30, 40, 50]

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