java - Java中如何统计数据

Question

我尝试通过以下代码计算数据并删除重复数据，但我收到此代码的错误消息。

有人可以帮助我吗？

StructorRecords.java

public class StructorRecords {

public String recorusername;
public String id;
public String full_name;
public String recordimg;
public Integer count;}

counter.java

public static void orderbylike(StructorRecords data) {
    if (G.bollike) {
        G.savelike.add(data);
    } else {
        Iterator itr = G.savelike.iterator();
        int i = 1;
        while (itr.hasNext()) {
            StructorRecords SR = (StructorRecords) itr.next();
            if (SR.id.equals(data.id)) {
                data.count = SR.count + 1;
                G.savelike.set(i, data);
            } else {
                G.savelike.add(data);
            }
            i++;
        }

    }
}

这是让我感动的日志日志

02-01 17:19:23.142 7587-9416/sanjinsgr.limosoftwaregroup.ir.instasanj W/System.err: java.util.ConcurrentModificationException
02-01 17:19:23.152 7587-9416/sanjinsgr.limosoftwaregroup.ir.instasanj W/System.err:     at java.util.ArrayList$ArrayListIterator.next(ArrayList.java:569)
02-01 17:19:23.152 7587-9416/sanjinsgr.limosoftwaregroup.ir.instasanj W/System.err:     at sanjinsgr.limosoftwaregroup.ir.instasanj.counter.orderbylike(counter.java:21)
02-01 17:19:23.152 7587-9416/sanjinsgr.limosoftwaregroup.ir.instasanj W/System.err:     at sanjinsgr.limosoftwaregroup.ir.instasanj.loginActivity$11.run(loginActivity.java:460)
02-01 17:19:23.162 7587-9416/sanjinsgr.limosoftwaregroup.ir.instasanj W/System.err:     at java.lang.Thread.run(Thread.java:856)
02-01 17:19:23.451 7587-9472/sanjinsgr.limosoftwaregroup.ir.instasanj W/System.err: java.util.ConcurrentModificationException
02-01 17:19:23.451 7587-9472/sanjinsgr.limosoftwaregroup.ir.instasanj W/System.err:     at java.util.ArrayList$ArrayListIterator.next(ArrayList.java:569)
02-01 17:19:23.451 7587-9472/sanjinsgr.limosoftwaregroup.ir.instasanj W/System.err:     at sanjinsgr.limosoftwaregroup.ir.instasanj.counter.orderbylike(counter.java:21)
02-01 17:19:23.461 7587-9472/sanjinsgr.limosoftwaregroup.ir.instasanj W/System.err:     at sanjinsgr.limosoftwaregroup.ir.instasanj.loginActivity$11.run(loginActivity.java:460)
02-01 17:19:23.461 7587-9472/sanjinsgr.limosoftwaregroup.ir.instasanj W/System.err:     at java.lang.Thread.run(Thread.java:856)
02-01 17:19:23.583 7587-9417/sanjinsgr.limosoftwaregroup.ir.instasanj W/System.err: java.util.ConcurrentModificationException
02-01 17:19:23.583 7587-9417/sanjinsgr.limosoftwaregroup.ir.instasanj W/System.err:     at java.util.ArrayList$ArrayListIterator.next(ArrayList.java:569)
02-01 17:19:23.583 7587-9417/sanjinsgr.limosoftwaregroup.ir.instasanj W/System.err:     at sanjinsgr.limosoftwaregroup.ir.instasanj.counter.orderbylike(counter.java:21)
02-01 17:19:23.583 7587-9417/sanjinsgr.limosoftwaregroup.ir.instasanj W/System.err:     at sanjinsgr.limosoftwaregroup.ir.instasanj.loginActivity$11.run(loginActivity.java:460)
02-01 17:19:23.592 7587-9417/sanjinsgr.limosoftwaregroup.ir.instasanj W/System.err:     at java.lang.Thread.run(Thread.java:856)

Answer 1

出现错误是因为您尝试将元素添加到列表中(我假设 G.savelike 是一个列表)，同时使用迭代器迭代同一个列表。

这是不允许的。相反，为所有新元素创建另一个 tmpList，将它们添加到其中，并在迭代器循环完成后使用 addAll() 方法。

像这样:

List<StructorRecords> tmpList = new ArrayList<StructorRecords> tmpList;
while (itr.hasNext()) {
        StructorRecords SR = (StructorRecords) itr.next();
        if (SR.id.equals(data.id)) {
            data.count = SR.count + 1;
            G.savelike.set(i, data);
        } else {
            // here put to temp list
            tmpList.add(data);
        }
        i++;
    }
    // add all new elements
    G.savelike.addAll(tmpList);