I have the following:
IEnumerable<Personel> personel= page.Retrieve<Personel>....
Then I have List which contains only personelIDs
List<int> personelIDs....
I need to retrived all 'personels' from the IEnumerable and assign it into a new List which matches the personelIDs from 'personelIDs ' list.
I can do it my iterating and having verify the IDs and if they're equal assign it into another List,
but is there a short here where I can retrieve it without iterating or having multiple lines of code?
Basically Is there a way on how to shortened this
List<int> pIds = ....// contains only specific personellID's
IEnumerable personelIEn = // contains Personel data like personel IDs, name..etc
List<Personel> personel = personelIEn.ToList();
List<Personel> personelByTag = new List<Personel>();
foreach (Personel b in personel ) {
if (pIds.Contains(b.DocumentID)) {
personelByTag .Add(b);
}
}
return personelByTag ;
basically I'm trying to find ways how to shortened the above code
You can use a predicate:
public List<Personel> search(String documentId, List<Personel> list)
{
Predicate<Personel> predicate = (Personel personel) => (personel.Id== documentId);
return list.FindAll(predicate);
}
Could that help?
Related
Suppose I have two class:
class Key {
private Integer id;
private String key;
}
class Value {
private Integer id;
private Integer key_id;
private String value;
}
Now I fill the first list as follows:
List<Key> keys = new ArrayLisy<>();
keys.add(new Key(1, "Name"));
keys.add(new Key(2, "Surname"));
keys.add(new Key(3, "Address"));
And the second one:
List<Value> values = new ArrayLisy<>();
values.add(new Value(1, 1, "Mark"));
values.add(new Value(2, 3, "Fifth Avenue"));
values.add(new Value(3, 2, "Fischer"));
Can you please tell me how can I rewrite the follow code:
for (Key k : keys) {
for (Value v : values) {
if (k.getId().equals(v.getKey_Id())) {
map.put(k.getKey(), v.getValue());
break;
}
}
}
Using Lambdas?
Thank you!
‐------UPDATE-------
Yes sure it works, I forget "using Lambdas" on the first post (now I added). I would like to rewrite the two nested for cicle with Lamdas.
Here is how you would do it using streams.
stream the keylist
stream an index for indexing the value list
filter matching ids
package the key instance key and the value instance value into a SimpleEntry.
then add that to a map.
Map<String, String> results = keys.stream()
.flatMap(k -> IntStream.range(0, values.size())
.filter(i -> k.getId() == values.get(i).getKey_id())
.mapToObj(i -> new AbstractMap.SimpleEntry<>(
k.getKey(), values.get(i).getValue())))
.collect(Collectors.toMap(Entry::getKey, Entry::getValue));
results.entrySet().forEach(System.out::println);
prints
Address=Fifth Avenue
Surname=Fischer
Name=Mark
Imo, your way is much clearer and easier to understand. Streams/w lambdas or method references are not always the best approach.
A hybrid approach might also be considered.
allocate a map.
iterate over the keys.
stream the values trying to find a match on key_id's and return first one found.
The value was found (isPresent) add to map.
Map<String,String> map = new HashMap<>();
for (Key k : keys) {
Optional<Value> opt = values.stream()
.filter(v -> k.getId() == v.getKey_id())
.findFirst();
if (opt.isPresent()) {
map.put(k.getKey(), opt.get().getValue());
}
}
I'm trying to add an element list to the list of string, but I found Kotlin does not have an add function like java so please help me out how to add the items to the list.
class RetrofitKotlin : AppCompatActivity() {
var listofVechile:List<Message>?=null
var listofVechileName:List<String>?=null
var listview:ListView?=null
var progressBar:ProgressBar?=null
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_retrofit_kotlin)
listview=findViewById<ListView>(R.id.mlist)
var apiInterfacee=ApiClass.client.create(ApiInterfacee::class.java)
val call=apiInterfacee.getTaxiType()
call.enqueue(object : Callback<TaxiTypeResponse> {
override fun onResponse(call: Call<TaxiTypeResponse>, response: Response<TaxiTypeResponse>) {
listofVechile=response.body()?.message!!
println("Sixze is here listofVechile ${listofVechile!!.size}")
if (listofVechile!=null) {
for (i in 0..listofVechile!!.size-1) {
//how to add the name only listofVechileName list
}
}
//println("Sixze is here ${listofVechileName!!.size}")
val arrayadapter=ArrayAdapter<String>(this#RetrofitKotlin,android.R.layout.simple_expandable_list_item_1,listofVechileName)
listview!!.adapter=arrayadapter
}
override fun onFailure(call: Call<TaxiTypeResponse>, t: Throwable) {
}
})
}
}
A more idiomatic approach would be to use MutableList instead of specifically ArrayList. You can declare:
val listOfVehicleNames: MutableList<String> = mutableListOf()
And add to it that way. Alternatively, you may wish to prefer immutability, and declare it as:
var listOfVehicleNames: List<String> = emptyList()
And in your completion block, simply reassign it:
listOfVehicleNames = response.body()?.message()?.orEmpty()
.map { it.name() /* assumes name() function exists */ }
Talking about an idiomatic approach... 🙄
When you can get away with only using immutable lists (which means usually in Kotlin), simply use + or plus. It returns a new list
with all elements of the original list plus the newly added one:
val original = listOf("orange", "apple")
val modified = original + "lemon" // [orange, apple, lemon]
original.plus("lemon") yields the same result as original + "lemon". Slightly more verbose but might come in handy when combining several collection operations:
return getFruit()
.plus("lemon")
.distinct()
Besides adding a single element, you can use plus to concatenate a whole collection too:
val original = listOf("orange", "apple")
val other = listOf("banana", "strawberry")
val newList = original + other // [orange, apple, banana, strawberry]
Disclaimer: this doesn't directly answer OP's question, but I feel that in a question titled "How to add an item to a list in Kotlin?", which is a top Google hit for this topic, plus must be mentioned.
If you don't want or can't use array list directly use this code for add item
itemsList.toMutableList().add(item)
itemlist : list of your items
item : item you want to add
instead of using a regular list which is immutable just use an arrayListof which is mutable
so your regular list will become
var listofVehicleNames = arrayListOf("list items here")
then you can use the add function
listOfVehicleNames.add("what you want to add")
you should use a MutableList like ArrayList
var listofVechileName:List<String>?=null
becomes
var listofVechileName:ArrayList<String>?=null
and with that you can use the method add
https://kotlinlang.org/api/latest/jvm/stdlib/kotlin.collections/-mutable-list/add.html
For any specific class, the following may help
var newSearchData = List<FIRListValuesFromServer>()
for (i in 0 until this.singleton.firListFromServer.size) {
if (searchText.equals(this.singleton.firListFromServer.get(i).FIR_SRNO)) {
newSearchData.toMutableList().add(this.singleton.firListFromServer.get(i))
}
}
val listofVechile = mutableListOf<String>()
Declare mutable list like that and you will be able to add elements to list :
listofVechile.add("car")
https://kotlinlang.org/docs/collections-overview.html
I have a list of sObject elements. I want to remove the duplicate element having the same record name along with the original record .
Like suppose if I have a list of element having record names as
Chair1,Chair2,Chair3,Chair4,Chair5,Chair6,Chair7,Chair1,Chair2
I want to print a list having only the elements that have no duplicates.For this case I should get the list Chair3,Chair4,Chair5,Chair6,Chair7.
I am using the below code to achieve this functionality.But I am getting thw records as : Chair1,Chair2,Chair3,Chair4,Chair5,Chair6,Chair7.
In ideal case we should not get the records Chair1,Chair2 as these already have duplicate records.
List <Chair__c> chairList = [SELECT
ID,
Name
FROM Chair__c
ORDER BY Name ASC];
System.debug('chairListOrderbyName::'+chairList);
List <String> chairNameList = new List <String>();
for(Integer i = 0; i < chairList.size();i++) {
for(Integer j = 0;j < chairList.size();j++) {
if(chairList[i].Name.equalsIgnoreCase(chairList[j].Name) && i != j) {
chairList.remove(i);
chairList.remove(j);
}
}
}
System.debug('chairList::'+chairList);
If names is really all you need you could do it with pure SOQL using GROUP BY and HAVING. Something like
SELECT Name
FROM Chair__c
GROUP BY Name
HAVING COUNT(Id) = 1 // only unique entries
If you need full sObjects then I'd make a helper Set<String> and loop through results. If name isn't in the set - add it. But if it already is there -> remove it!
Actually let's make it Map, similar idea...
Map<Set, Chair__c> chairs = new Map<Set, Chair__c>();
for(Chair__c c : [SELECT ...]){
if(chairs.containsKey(c.Name)){
chairs.remove(c.Name);
} else {
chairs.put(c.Name, c);
}
}
System.debug(JSON.serializePretty(chairs));
System.debug(chairs.values());
Try using a Set<String> instead of List<String>.Refer below solution
List <Chair__c> chairList = [SELECT
ID,
Name
FROM Chair__c
ORDER BY Name ASC];
Set<String> chairNameSet = new Set<String>();
for(String item: chairList ) {
chairNameSet.add(item);
}
Is there a way of dynamically building a cypher query using spring data neo4j?
I have a cypher query that filters my entities similar to this one:
#Query("MATCH (n:Product) WHERE n.name IN {0} return n")
findProductsWithNames(List<String> names);
#Query("MATCH (n:Product) return n")
findProductsWithNames();
When the names list is empty or null i just want to return all products. Therefore my service impl. checks the names array and calls the correct repository method. The given example is looks clean but it really gets ugly once the cypher statements are more complex and the code starts to repeat itself.
You can create your own dynamic Cypher queries and use Neo4jOperations to execute them. Here is it an example (with a query different from your OP) that I think can ilustrate how to do that:
#Autowired
Neo4jOperations template;
public User findBySocialUser(String providerId, String providerUserId) {
String query = "MATCH (n:SocialUser{providerId:{providerId}, providerUserId:{providerUserId}})<-[:HAS]-(user) RETURN user";
final Map<String, Object> paramsMap = ImmutableMap.<String, Object>builder().
put("providerId", providerId).
put("providerUserId", providerUserId).
build();
Map<String, Object> result = template.query(query, paramsMap).singleOrNull();
return (result == null) ? null : (User) template.getDefaultConverter().convert(result.get("user"), User.class);
}
Hope it helps
Handling paging is also possible this way:
#Test
#SuppressWarnings("unchecked")
public void testQueryBuilding() {
String query = "MATCH (n:Product) return n";
Result<Map<String, Object>> result = neo4jTemplate.query(query, Collections.emptyMap());
for (Map<String, Object> r : result.slice(1, 3)) {
Product product = (Product) neo4jTemplate.getDefaultConverter().convert(r.get("n"), Product.class);
System.out.println(product.getUuid());
}
}
I have a method which select the row whose rowkey contains the parameter passed into.
HTable table = new HTable(Bytes.toBytes(objectsTableName), connection);
public List<ObjectId> lookUp(String partialId) {
if (partialId.matches("[a-fA-F0-9]+")) {
// create a regular expression from partialId, which can
//match any rowkey that contains partialId as a substring,
//and then get all the row with the specified rowkey
} else {
throw new IllegalArgumentException(
"query must be done with hexadecimal values only");
}
}
I don't know how to finish code above.
I just know the following code can get the row with specified rowkey in Hbase.
String rowkey = "123";
Get get = new Get(Bytes.toBytes(rowkey));
Result result = table.get(get);
You can use RowFilter filter with RegexStringComparator to do that. Or, if it is just to fetch the rows which match a given substring you can use RowFilter with SubstringComparator. This is how you use HBase filters :
public static void main(String[] args) throws IOException {
Configuration conf = HBaseConfiguration.create();
HTable table = new HTable(conf, "demo");
Scan s = new Scan();
Filter f = new RowFilter(CompareOp.EQUAL, new SubstringComparator("abc"));
s.setFilter(f);
ResultScanner rs = table.getScanner(s);
for(Result r : rs){
System.out.println("RowKey : " + Bytes.toString(r.getRow()));
//rest of your logic
}
rs.close();
table.close();
}
The above piece of code will give you all the rows which contain abc as a part of their rowkeys.
HTH