比较数组之间的所有元素并返回所有可能的匹配项

Question

我正在尝试创建一个函数，该函数将数组的所有元素与第二个数组的所有元素进行比较，并将返回所有可能的匹配项，如果未找到匹配项，则返回消息。当我尝试实现代码时，我得到一个索引越界错误。内部 for 循环可能在外部 for 循环完成运行之前达到最大值。如何修改它以防止发生这种情况？

Stocks[] stockList3 = new Stocks[3];

stockList3[0] = new Stocks("a", 2, 1, "Buy");

stockList3[1] = new Stocks("a", 3, 1, "Buy");

stockList3[2] = new Stocks("a", 4, 1, "Buy");

Stocks[] stockList4 = new Stocks[3];

stockList4[0] = new Stocks("a", 2, 1, "Buy");

stockList4[1] = new Stocks("a", 5, 1, "Buy");

stockList4[2] = new Stocks("a", 4, 1, "Buy");

public void matching(Stocks[] array1, Stocks[] array2) {

    for (int i = 0; i < array1.length; i++) {

        for (int j = 0; i < array2.length; j++) {

            if (array1[i].stockPrice == array2[j].stockPrice) {

                System.out.println("It's a match at $" + array1[i].stockPrice);

            }

            System.out.println("still searching...");

        }

        System.out.println("first loop test...");

    }

}

Answer 1

如何代替两个，使用集合来存储数组之一的存在？for loopsSetstockPricespublic static List<Stocks> matching(Stocks[] one, Stocks[] two) {&nbsp; &nbsp; Set<Integer> stockPrices = Arrays.stream(one)&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;.map(stock -> stock.stockPrice)&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;.collect(Collectors.toSet());&nbsp; &nbsp; return Arrays.stream(two)&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;.filter(stock -> stockPrices.contains(stock.stockPrice))&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;.collect(Collectors.toList());}它使用 O（n） 附加内存（其中 n 为 1.length）和 O（n + m） 性能时间（其中 m 为 2.length）。

Answer 2

在你的j循环中，你说的不是i<array2.lengthj<array2.lengthpublic void matching ( Stocks[] array1, Stocks[] array2){&nbsp; &nbsp; for (int i=0; i<array1.length;i++){&nbsp; &nbsp; &nbsp; &nbsp; for (int j=0;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;j<array2.length;&nbsp; //this j was an i&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;j++){&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; if (array1[i].stockPrice == array2[j].stockPrice){&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; System.out.println("It's a match at $" + array1[i].stockPrice);&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; System.out.println("still searching...");&nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; &nbsp; System.out.println("first loop test...");&nbsp; &nbsp;&nbsp; &nbsp; }}