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I need someone who can write Java Streams. I want to write this code as a Java stream type [closed]

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public List testList(List numberList) {
List realList = new ArrayList();
for (Iterator iterator = numberList.iterator(); iterator.hasNext();) {
String num = (String) iterator.next();
realList.add(call(num));
}
return realList;
}
I want to write this code as a Java stream type.

I think you nead that:
numberList.stream()
.map(arg-> arg.toString())
.map(arg -> call(arg))
.collect(Collectors.toList());

public List testList(List numberList) {
return numberList.stream()
.map(s -> call((String) s))
.collect(Collectors.toList());
}

Removing all values from HashMap but keeping the keys? [closed]

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I am trying to delete all values associated with all keys in my HashMap, but still keep the keys.
Is the below correct / the most efficient way to do so?
for (Map.Entry<Kennel, List<Dog>> entry : hashMap.entrySet()) {
String key = entry.getKey().getId();
List<Dog> dogList = entry.getValue();
//Loop through the list associated with each key and delete each Dog in the list
for (int i=0; i<dogList.size(); i++){
dogService.delete(dogList.get(i));
dogService.save(dogList.get(i));
}
}

Simpler:
for(dogs : hashMap.values()) {
for(dog : dogs) {
dogService.delete(dog);
dogService.save(dog);
}
dogs.clear();
}

I don't know what you are trying to accomplish here but if you just want the unique keys then probably you should be using a HashSet instead of HashMap.
But, if you want to perform the deletion you can just do the following:
for (Kennel key : hashMap.keySet()) {
hashMap.put(key, null);
}
I have written Kennel key assuming that key of your HashMap is of type Kennel.

You could use at the end:
hashMap.put(entry.getKey(), null);
removing the whole list, but if you want put new dogs into it in the future (as I think you want), and your dog lists are modifiable, the following approach is more memory-friendly:
for (Map.Entry<Kennel, List<Dog>> entry : hashMap.entrySet()) {
String key = entry.getKey().getId();
Iterator<Dog> it = entry.getValue().iterator();
while (it.hasNext()) {
Dog dog = it.next();
dogService.delete(dog);
dogService.save(dog);
it.remove();
}
}
since you avoid allocating new lists in the future. Notice also the usage of it.remove() that allows deletion while iterating

cannot convert from ArrayList<Integer> to ArrayList<String> [closed]

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I have a ArrayList with integer value and I want to read this value from another ArrayList consist string value. How can I do that ?
public static ArrayList<Integer> scorerValue = new ArrayList<Integer>();
and I want read here using
ArrayList<String> score_Number ;

Okay. So let's first declare our List<String>..
List<String> score_Number = new ArrayList<String>();
// Remember you program to an interface. Not a concrete implementation.
Then to convert you..
// Do some magic.
That's right Magic. Magic involving the toString() method. You will need to call toString() in a for each loop. Finally, you will need to use the List.add() method, to add the newly created String values to your list score_Number.
NOTE: Follow the naming conventions. score_Number should be scoreNumber.

Try,
ArrayList<Integer> integerList = new ArrayList<Integer>();
// add Integer Elements
ArrayList<String> stringList = new ArrayList<String>();
for(Integer i : integerList){
stringList.add(i+"");
}

try this:
ArrayList<Integer> scorerValue = new ArrayList<Integer>();
scorerValue.add(1);
ArrayList<String> score_Number = new ArrayList<String>();
for (Integer i : scorerValue)
score_Number.add(i.toString());
System.out.println(score_Number);

Have complication with ArrayList of ArrayList [closed]

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I am implementing an algorithm,for that I need to use ArrayList of ArrayList.I want to retrieve each ArrayList from the Main ArrayList.
Eg: If the Main ArrayList contains 5 ArrayList and Each ArrayList in the main list contains 5 rows.
MainArrayList:
[1,2,3,4,5,a , 2,3,4,5,3,b , 7,8,9,4,5,d] //1st Arraylist
[1,2,3,4,5,e , 2,3,4,5,3,n , 7,8,9,4,5,e] //11nd Arraylist
[1,2,3,4,5,f , 2,3,4,5,3,t , 7,8,9,4,5,q] //111rd Arraylist
[1,2,3,4,5,c , 2,3,4,5,3,b , 7,8,9,4,5,a] //1vth Arraylist
[1,2,3,4,5,r , 2,3,4,5,3,m , 7,8,9,4,5,z] //v th Arraylist
I need to access each ArrayList from the main list and print it's content row by row
i.e for example
print 1st ArrayList from the main list.
1,2,3,4,5,a
2,3,4,5,3,b
7,8,9,4,5,d
similarly I need to print all arraylist in the main list same as above.

you can do it using ArrayList
List<List<Object>> twoDimArray = new ArrayList<ArrayList<>>();
twoDimArray.add(Arrays.asList("1","2","3");
for(List<Object> list: twoDimArray){
for(Object o : list){
System.out.println(o.toString());
}
}
And of course using HashMap:
Map<String,List<Object>> map = new HashMap<String,List<Object>>();
for (Map.Entry<String, String> entry : map.entrySet())
{
System.out.println(entry.getKey() + "/" + entry.getValue());
}

Use HashMap for resolving this problem.

Data defined String to Array [closed]

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I'm working on a game and I'm implementing objects where you can define in "TiledMap editor" what items a certain object holds.
So I've got to an idea where I can enter the Item ID's right there like {22:4, id:amount}. When I parse the map, I retrieve that array as a string, is there a way to convert it to an array?
Thanks in advance!

Firstly, you probably want a Map, not an array or a List.
Map<String,String> processParams(String list) {
Map<String,String> = new HashMap<String,String>();
int openBracket = list.indexOf("{");
int closeBracket = list.lastIndexOf("}");
String params = list.substring(openBracket+1,closeBracket);
String paramList = params.split(",");
for(String param: paramList) {
String pData = param.trim().split(":");
map.put(param[0].trim(),param[1].trim());
}
return map;
}
processParams("{22:4, id:amount}");
Of course, it's actually a JSON-like structure so there's probably pre-existing parsers.