目标:我必须有两个 OSD 类型的排序数组列表(导入库的类部分)。我需要将它们合并以以最优化的方式创建最终的排序列表(按时间降序排列)。
Problem : I can't modify the user defined OSD class as its part of an library and hence I cant edit and make it implements Comparable class. I have already created the function which performs the task, but it I want to optimize the code and make it less expensive.
我遇到过许多涉及实现 Comparable 的解决方案,但我做不到。
我想要优化以获得更好性能的当前工作代码
private ArrayList<OSD> latestFistSortMergeOsds(
ArrayList<OSD> awbThingTypeOSDs,
ArrayList<OSD> LDDthingTypeOSDs) {
ArrayList<OSD> sortedOsds = new ArrayList<OSD>();
ArrayList<Long> timestampList = null;
HashMap<Long, OSD> awbThingTypeOSDsHmap = null;
if (awbThingTypeOSDs != null) {
awbThingTypeOSDsHmap = new HashMap<Long, OSD>();
for (OSD mOSD : awbThingTypeOSDs) {
awbThingTypeOSDsHmap.put(mOSD.getUpdatedOn()
.getTime(), mOSD);
}
Log.i("sorted", "hmap" + awbThingTypeOSDsHmap);
}
HashMap<Long, OSD> LDDthingTypeOSDsHmap = null;
if (LDDthingTypeOSDs != null) {
LDDthingTypeOSDsHmap = new HashMap<Long,OSD>();
for (OSD nOSD : LDDthingTypeOSDs) {
LDDthingTypeOSDsHmap.put(nOSD.getUpdatedOn()
.getTime(), nOSD);
}
}
// merge n sort timestamp
if (awbThingTypeOSDsHmap != null) {
timestampList = new ArrayList<Long>(awbThingTypeOSDsHmap.keySet());
if (LDDthingTypeOSDsHmap != null) {
ArrayList<Long> timestampListLDD = new ArrayList<Long>(
LDDthingTypeOSDsHmap.keySet());
timestampList.addAll(timestampListLDD);
}
Collections.sort(timestampList, Collections.reverseOrder());// descending
Log.i("sorted", "sorted keyList" + timestampList);
}
// merge sorted osds- latest first
// timestamplist is sorted in desc order
if (timestampList != null) {
for (Long timestampKey : timestampList) {
RareMediaCompanyOSD osd = null;
osd = awbThingTypeOSDsHmap.get(timestampKey);
if (osd == null) {
osd = LDDthingTypeOSDsHmap.get(timestampKey);
}
sortedOsds.add(osd);
}
}
return sortedOsds;
}
我引用了以下链接 Comparing Long values using Collections.sort(object)
Comparing Long values using Collections.sort(object)
How to sort ArrayList<Long> in Java in decreasing order?
请建议更好地使用 Hashmap,或者我应该使用其他 DS 而不是 hashmap 来优化代码。
P.S:它不是这些问题的重复,因为我无法编辑类并实现类似的,因为它是库的一部分。
谢谢!
最佳答案
我建议创建一个holder类,它保存一个OSD
对象,该对象又实现Comparable
public class OSDHolder implements Comparable<OSDHolder> {
private final OSD obj;
public OSDHolder(OSD obj) {
this.obj = obj;
}
public long getTiming() {
this.obj.getUpdatedOn().getTime();
}
@Override
public int compareTo(OSDHolder o) {
if (this.getTiming() > o.getTiming())
return 1;
else if (this.getTiming < o.getTiming())
return -1;
return 0;
}
}
然后,您可以简单地将两个列表的内容添加到一个列表中,作为 OSDHolder
类型
ArrayList<OSDHolder> holders = new ArrayList<>();
for (OSD osd:awbThingTypeOSDs) {
holders.add(new OSDHolder(osd));
}
for (OSD osd:LDDthingTypeOSDs) {
holders.add(new OSDHolder(osd));
}
然后使用 Collections.sort()
或 Arrays.sort()
对 holders
进行排序
关于java - 对两个用户定义类型Library类的Arraylist进行排序和合并,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/27289245/