My hashmap key returns this: MemorySection[path='rr', root='YamlCofiguration']=1
Is there anyway I can get the value of path=''. I know that I can get the value of the root='' using getValue(), although I only really use this for keeping track of the highest and lowest values to then order them from highest to lowest.
I have tried this thread although the answers presume that I would know what the pair's name is. Retrieving Key from the Hash Map
EDIT:
Here is how I'm setting the data and sorting it as well. I am accessing it through the likesList List
HashMap<String, Integer> likes = new HashMap<>();
for(String key: playersFile.getKeys(false)) {
likes.put(playersFile.getString(key), playersFile.getInt(key + ".likes"));
}
List<Entry<String, Integer>> likesList = new LinkedList<Entry<String, Integer>>(likes.entrySet());
Collections.sort(likesList, new Comparator<Entry<String, Integer>>() {
public int compare(Entry<String, Integer> o1, Entry<String, Integer> o2) {
return o2.getValue() - o1.getValue();
}
});
for (int i = 0; i<45; i++) {
try {
String name1 = cookiesList.get(i).getKey();
item = name(name1);
publicinv.setItem(i, item);
} catch (IndexOutOfBoundsException e) {
}
}
I still don't really know what you want, but here is a guess I made:
// your input
String name1 = "MemorySection[path='rr', root='YamlCofiguration']=1";
// this string indicates the start of the path
String start = "path='";
// where the path starts
int pathStart = name1.indexOf(start)+start.length();
// where the path ends
int pathEnd = name1.substring(pathStart).indexOf("'") + pathStart;
// get the path
System.out.println( name1.substring(pathStart, pathEnd) ); // prints: rr
Related
I have a list of custom object,
public class Assignmentsdata {
String assignmentId;
String teacherId;
String groupName;
String sectionId;
String levelId;
String startTime;
}
ArrayList<Assignmentsdata> list = new ArrayList<>();
lets say there are 20 elements in that list.
Now I want to get the output which is a hashmap of startTime as a key and the Value would be a new HashMap of GroupID and a list of Assignments of those that had the same groupName.
OutPut Example
HashMap<startTime,HasMap<groupName,List> hashMap = new HashMap();
a little more insight about the problem: First I want to categorise based on startTime(Month) then i want to categorise based on groupName, Thanks in advance.
I have successfully categorised based on group name and created a map through below code:
for( int i = 0; i<assignmentsdataArrayList.size();i++ ){
if (hashMap.size()>0){
hashMap.get(assignmentsdataArrayList.get(i).getGroupName()).add(assignmentsdataArrayList.get(i));
}else {
hashMap.put(assignmentsdataArrayList.get(i).getGroupName(),new ArrayList<Assignmentsdata>());
hashMap.get(assignmentsdataArrayList.get(i).getGroupName()).add(assignmentsdataArrayList.get(i));
}
}
After that I am lost on how to categorise this hashmap based on the startDate and create a hashmap that would look like the above hashmap in the output heading.
your code may throw a NullPointerException at the first if branch
if (hashMap.size()>0)
{hashMap.get(assignmentsdataArrayList.get(i).getGroupName()).add(assignmentsdataArrayList.get(i));
}
the map.size()>0 doesnt means the Value of GroupName has put a new ArrayList already.
the anwser of using loop should like this
Map<String, Map<String, List<Assignmentsdata>>> map = new HashMap<>();
for (Assignmentsdata assignmentsdata : list) {
if (!map.containsKey(assignmentsdata.getStartTime())) {
map.put(assignmentsdata.getStartTime(), new HashMap<>());
}
Map<String, List<Assignmentsdata>> startTimeMap = map.get(assignmentsdata.startTime);
if (!startTimeMap.containsKey(assignmentsdata.getGroupName())) {
startTimeMap.put(assignmentsdata.getGroupName(), new ArrayList<>());
}
startTimeMap.get(assignmentsdata.groupName).add(assignmentsdata);
}
or you could use the java stream().collect(Collectors.groupingBy()) api to get the result easily
Map<String, Map<String, List<Assignmentsdata>>> result = list.stream()
.collect(Collectors.groupingBy(Assignmentsdata::getStartTime,Collectors.groupingBy(Assignmentsdata::getGroupName)));
I am answering my own question as I solved it if anyone has a better answer please passed your answer aswell, ill accept another answer suitable and efficient answer.
for( int i = 0; i<assignmentsdataArrayList.size();i++ ){
if (hashMap.size()>0){
if (hashMap.get(assignmentsdataArrayList.get(i).getGroupName())==null){
hashMap.put(assignmentsdataArrayList.get(i).getGroupName(),new ArrayList<Assignmentsdata>());
hashMap.get(assignmentsdataArrayList.get(i).getGroupName()).add(assignmentsdataArrayList.get(i));
}else{
hashMap.get(assignmentsdataArrayList.get(i).getGroupName()).add(assignmentsdataArrayList.get(i));
}
}else {
hashMap.put(assignmentsdataArrayList.get(i).getGroupName(),new ArrayList<Assignmentsdata>());
hashMap.get(assignmentsdataArrayList.get(i).getGroupName()).add(assignmentsdataArrayList.get(i));
}
}
// above part is already in the question. the second part i looped through the hashMap then the list once again, and checking if list and map entry have same group name, then made the startdate key that indexed element from the list.
HashMap<String, Map.Entry<String, ArrayList<Assignmentsdata>>> hashMapHashMap = new HashMap<>();
for (var entry : hashMap.entrySet()){
for( int j = 0; j<assignmentsdataArrayList.size();j++ ){
if (assignmentsdataArrayList.get(j).getGroupName()==entry.getKey()){
hashMapHashMap.put(assignmentsdataArrayList.get(j).getStartTime(),entry);
}
}
hashMapHashMap.put(entry.getValue().get())
}
Hey guys currently have problem with regards to removing duplicates from hashmap.
Some background:
My hashmap is in this format Map<CompositeKeyBean,ValueBean>.
CompositeKeyBean is in the form (String ID, String hashvalue);
ValueBean is an object.
So if i have a hashmap with values as such:
(ID:1,HashValue:123),Obj1
(ID:1,HashValue:234),Obj1
(ID:1,HashValue:345),Obj1
I need to remove the duplicate keys and only have items with unique IDs. currently I have come up with this, But it does not seem to work, im pretty sure i am doing something wrong.
for (Map.Entry<CompositeKeyBean, ReportDataBean> entry : list.entrySet())
{
String idvalue = entry.getKey().getCompositeKeyList().get(0);
for(int i = 1; i < list.size();i++)
{
if(list.keySet().contains(idvalue))
{
list.remove(i);
}
}
}
My solution for this one would be to declare first an another Map which will be used to hold the number of times that a certain key has appeared in the original Map. For the second time, you can iterate the same map entrySet and remove the duplicates using the declared additional Map as reference.
Map<String, Integer> numberOfInstanceMap = new HashMap<String, Integer>(); //temporary placeholder
for (Map.Entry<CompositeKeyBean, ReportDataBean> entry : list.entrySet())
{
String idvalue = entry.getKey().getCompositeKeyList().get(0);
if(!numberOfInstanceMap.containsKey(idvalue)) {
numberOfInstanceMap.put(idvalue, 1); //initialize the key to 1
} else {
numberOfInstanceMap.replace(idValue, numberOfInstanceMap.get(idValue) + 1); //add 1 to the existing value of the key
}
}
for (Map.Entry<CompositeKeyBean, ReportDataBean> entry : list.entrySet())
{
String idvalue = entry.getKey().getCompositeKeyList().get(0);
Integer i = numberOfInstanceMap.get(idValue);
if(i>1) { //remove duplicate if the key exists more than once
list.remove(idValue);
}
}
If you are expecting duplicate keys, then you can do the following way to handle it while populating the map itself:
Map<String, String> map = new HashMap<>();
if(map.containsKey("ID")){
String oldValue = map.get("ID");
//put logic to merge the value
}else{
map.put("ID","newValue");
}
Entry which needs to compare with the List and get the value from Map which is not there is the List.
for (Map.Entry<String, Object> entry : itemObj.entrySet())
{
System.out.println(entry.getKey());
for (ItemProcessVO processVO : itemDetails2){
if (entry.getKey().equalsIgnoreCase(processVO.getAccount())){
String account = processVO.getAccount();
lstAccVO.add(account);
}
}
}
This is the code i have used.I have Map of entry.getKey() has 6 Values while itemDetail2 has only 5 elements.I need to display only the missing account after comparing.
Simply add an else-statement to your if clause that stores that account in a local variable. Then after your for loops you can do whatever with that.
Hint: you can use loop over Map#keySet() instead of Map#entrySet() and bypass the entries that way.
In the provided example you compared the key with the account, simply use the else- statement to find the missingAccounts to iterate after this loop over them.
List<ItemProcessVO> missingAccounts= new ArrayList<>();
for (Map.Entry<String, Object> entry : itemObj.entrySet())
{
System.out.println(entry.getKey());
for (ItemProcessVO processVO : itemDetails2){
if (entry.getKey().equalsIgnoreCase(processVO.getAccount())){
String account = processVO.getAccount();
lstAccVO.add(account);
}else{
missingAccounts.add(account)
}
}
}
Below code should do the trick. It uses case insensitive comparison and prints remaining keys in the end, more explanation is in comments:
public static void main(String[] args) throws IOException {
Map<String, Object> itemObj = new HashMap<>(); //Your Map
List<ItemProcessVO> itemDetails2 = new ArrayList<>();// Your list
//First, get all the keys of the map
Set<String> keys = new HashSet<>(itemObj.keySet());
//Now, iterate through list and remove the matching items
for(ItemProcessVO processVO : itemDetails2){
String key = pop(keys, processVO.getAccount());
//If key is not null then remove it
if(null != key){
keys.remove(key);
}
}
//Now, iterate through remaining keys and print the values
for(String key : keys){
System.out.println("Missing value " + itemObj.get(key));
}
}
private static String pop(Set<String> set, String key){
if(null == set){
return null;
}else{
for(String element : set){
if(element.equalsIgnoreCase(key)){
return element;
}
}
}
}
I have a list of workStatuses. Each workStatus has its name and time. I can do workStatus.getName() while iterating through every workStatus.
for (workStatus ws: workStatuses) {
String name = ws.getName();
}
Next I have a list of names called nameList.
List<String> nameList = new ArrayList<String>();
nameList.add("Completed");
nameList.add("Failed");
Now I am using HashMap to count number of workStatuses each name has.So I have to
Iterate through workStatuses.
For each workStatus, find the name.
Check if that name exist in my nameList.
If yes, then increase the
number of Workstatus for that name and put that count on HashMap.
What I have done:
Integer numberOfWorkStatus =0;
Map<String,Integer> hm = new HashMap<String,Integer>();
for(WorkStatus ws: workStatuses) {
if (ws.getName()!=null && nameList.contains(ws.getName())) {
numberOfWorkStatus++;
hm.put(ws.getName(), numberOfWorkStatus);
}
}
return hm;
Can anyone suggest me if I am doing it the right way?
You can use stream API and if I get right do something like this:
// List<WorkStatus> workStatuses = ...
workStatuses.stream().collect(
Collectors.groupingBy(WorkStatus::getName, Collectors.counting()));
as a result you will have Map<String, Long>
You can do that this way :
for(Stirng name :nameList)
hm.put(name, 0);
for(WorkStatus ws: workStatuses) {
if( hm.get(ws.getName() != null)
hm.put(ws.getName(), hm.get(ws.getName()) + 1);
}
hm will contains the count of each name that is exists in the workStauses.
You can change this to :
for (String str:nameList){
if (str.contains(ws.getName())) {
totalCount++;
hm.put(ws.getName(), totalCount);
}
}
You cannot check for a String directly from a list and the one you put in HM should be ws.
Map<String, Integer> hm = new HashMap<>();
for (WorkStatus ws : workStatuses) {
if (ws.getName() != null && nameList.contains(ws.getName())) {
hm.putIfAbsent(ws.getName(), 0);
hm.put(ws.getName(), hm.get(ws.getName()) + 1);
}
}
I'm trying to create a PhoneBook class that uses a HashMap in Java. When I add an entry using the put() method in addContact(), it works fine, but when I try to retrieve values in the searchContact() method, none are returned. I'm not getting null values; HashMap definitely contains the key(s) I am searching for, but the values associated with the key(s) are not being returned. Thank you in advance.
Here is my code:
public class PhoneBookContactsImpl {
private Map<String, List<String>> contactMap = new HashMap<String, List<String>>();
public void addContact(String name, List<String> list) {
contactMap.put(name, list);
//its working fine here
System.out.println(contactMap.get(name));
}
public Map<String, List<String>> getContactMap() {
Set set = contactMap.entrySet();
Iterator i = contactMap.entrySet().iterator();
while (i.hasNext()) {
Map.Entry me = (Map.Entry) i.next();
System.out.println(me.getKey() + " : ");
List<String> nos = (List<String>) me.getValue();
System.out.println("Nos = " + nos + " n ");
System.out.println(nos.size());
}
return contactMap;
}
public List<String> searchContact(String name) throws NoDataFoundException {
if (contactMap.isEmpty()) {
System.out.println("Empty PhoneBook");
throw new NoDataFoundException();
} else {
if (contactMap.containsValue(name))
return contactMap.get(name);
//it doesnt retrieve valur from here
else {
System.out.println("No Entry for Specified Entry");
throw new NoDataFoundException();
}
}
}
}
your if statement is checking if the phonebook has name as a value, so your get is never reached.
Try this:
if (contactMap.containsKey(name))
return contactMap.get(name);
As the other answer points out you should be checking containsKey because name is a key, not a value. But why not make the whole thing much easier:
public List<String> searchContact(String name) throws NoDataFoundException {
List<String> result = contactMap.get(name);
if (result == null) {
// empty map, or no matching value or value is null
throw new NoDataFoundException();
}
}
You are doing:
if (contactMap.containsValue(name))
return contactMap.get(name);
and you need to do:
if (contactMap.containsKey(name))
return contactMap.get(name);