在Java中查找匹配对象

1 周，5 日 Questions & Answers 1896

我目前正试图根据两个对象的值匹配它们。除了，它不是a.a = a.a，而是a.a = a.b和a.b = b.a。这意味着覆盖equals是一个选项，但它肯定不是正确的选项

虽然对这些对象进行排序将加快匹配时间，但总体数量将很小，因此没有必要。另外，compareTo也不完全正确，原因与equals相同

我是否只是制定自己的方法以防万一？将有4个字段要匹配，这就是为什么我不在前面使用if语句的原因

public boolean isOpposite(Object other) { return (this.a == other.b) ? true : false; }

还有一种可能性是，对象将实现/扩展一个基础对象，以获得更多字段并实现其自己的匹配方式

我正在考虑使用LinkedList，因为我知道它比ArrayList快，但是我也在考虑使用Map。编辑：更好地解释对象

public class Obj { public String a; public String b; public String c; public double d; }

这些关系如下：

Obj obj1, obj2; obj1.a == obj2.b //.equals for String of course obj1.b == obj2.a obj1.c == obj2.c obj1.d == obj2.d * -1

# 1 楼答案

我已经做了一些测试，并确定我知道如何实现这一点的最干净的方法是使用ArrayList<Obj>

这是我的实现：

public static List<ObjGroup> getNewSampleGroup(int size) {
    List<ObjGroup> sampleGroup = new ArrayList<ObjGroup>();
    sampleGroup.add(new ObjGroup((generateNumbers(size, 1)))); //Positives
    sampleGroup.add(new ObjGroup((generateNumbers(size, -1)))); //Negatives
    return sampleGroup;
}

private static List<Obj> generateNumbers(int size, int x) {
    List<Obj> sampleGroup = new ArrayList<Obj>();
    for (int i = 0; i < size; i ++) {
        Random rand = new Random();
        String randC;
        String randA;
        String randB;
        double randD;

        if (x == 1) {
            randD = rand.nextInt((maxP - minP + 1) + minP);
            randA = "aval";// + String.valueOf(rand.nextInt((max - min + 1) + min));
            randB = "bval";// + String.valueOf(rand.nextInt((max - min + 1) + min));
            randC = "cval";// + String.valueOf(rand.nextInt((max - min + 1) + min));
        } else {
            randD = rand.nextInt((maxP - minP + 1) + minP) * -1;
            randA = "bval";// + String.valueOf(rand.nextInt((max - min + 1) + min));
            randB = "aval";// + String.valueOf(rand.nextInt((max - min + 1) + min));
            randC = "cval";// + String.valueOf(rand.nextInt((max - min + 1) + min));
        }
        sampleGroup.add(new Obj(randA, randB, randC, randD));
    }
    return sampleGroup;
}

public List<ObjGroup> findMatches(List<ObjGroup> unmatchedList) {
    List<Obj> pivotPos = unmatchedList.get(0).getObjs(); //First grouping are positives
    List<Obj> pivotNeg = unmatchedList.get(1).getObjs(); //Second grouping are negatives
    List<ObjGroup> matchedList = new ArrayList<ObjGroup>();
    long iterations = 0;

    Collections.sort(pivotPos);
    Collections.sort(pivotNeg, Collections.reverseOrder());

    for (Iterator<Obj> iteratorPos = pivotPos.iterator(); iteratorPos.hasNext();) {
        final Obj focus = iteratorPos.next();
        iteratorPos.remove(); //Remove this once pulled as you won't match it again.
        for (Iterator<Obj> iteratorNeg = pivotNeg.iterator(); iteratorNeg.hasNext();) {
            final Obj candidate = iteratorNeg.next();
            if (compare(focus, candidate)) {
                matchedList.add(new ObjGroup(new ArrayList<Obj>() {
                    {
                        add(focus);
                        add(candidate);
                    }
                }));
                iteratorNeg.remove(); //Remove this once matched as you won't match it again.
                break;
            }
            iterations ++;
        }
        iterations ++;
    }
    return matchedList;
}

我对4000000个psuedo randomObj对象的样本进行了测试。这是我的输出：

Starting matching test.
18481512007 iterations.
3979042 matched objects.
10479 unmatched objects.
Processing time: 44 minutes.
There were 1989521 number of matches found.
Closing matching test.

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在Java中查找匹配对象

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