In list find lenghtOfArgument with lambda in Java

Question

In my taks I need to find size() of argument and for every object print size. Object of type Car are in Set(so this maybe should help)

I did this:

List<Integer> numberOf = cars
.stream
.map(car->car.getNumbers().size())
.collect(Collectors.toList());

System.out.println(numberOf);

Output is : [1,1,1,1]

I need output like this:

Audi - 1 Bmw - 1 Porsche - 1 Bentley - 1

If I go with

for(Car c: cars)
sout(c.getName + numberOf)

It gets me Audi [1,1,1,1] Bmw[1,1,1,1]etc.

How to properly print all those values. I also tried to Override method toString in class car but I also get the same output.

Edit: Class Car

public Car(String name, List<Colours> colours)
super(name);
this.colours= colours;

System.out.println @NomadMaker – sdavb Nov 18 '20 at 23:39 — sdavb, Nov 18 '20 at 23:39

Jackkobec · Answer 1 · 2020-11-19T00:30:00.637

0

The simplest solution is:

    cars.forEach(car -> 
            System.out.println(car.getName() + " - " + car.getNumbers().size()));

Grouping by name:

import java.util.stream.Collectors;

import static java.util.stream.Collectors.counting;
import static java.util.stream.Collectors.groupingBy;


Collection<Car> cars = ...// your cars
final Map<String, Long> grouped = 
    cars.stream()
        .collect(groupingBy(car -> car.getName(), counting()));
System.out.println(grouped);

edited Nov 19 '20 at 00:30

answered Nov 18 '20 at 23:37

Jackkobec

5,889
34
34

I need to include map – sdavb Nov 18 '20 at 23:45
It says no instance of type(s) of type variable (R) exist so that void confronts to R – sdavb Nov 18 '20 at 23:50
if you need only print forEach is enough – Jackkobec Nov 18 '20 at 23:56
use grouping that I'd added into the answer – Jackkobec Nov 19 '20 at 00:31
I need to use map after stream() not Map – sdavb Nov 19 '20 at 00:37

score 0 · Accepted Answer · answered Nov 19 '20 at 00:38

0

If you want output like "name - number", perhaps generate strings:

List<String> combined = cars
.stream
.map(car->car.getName + " - " + car.getNumbers().size())
.collect(Collectors.toList());

System.out.println(combined);

answered Nov 19 '20 at 00:38

tevemadar

12,389
3
21
49

This is the one! Tnx for helping – sdavb Nov 19 '20 at 00:46
Do you know how to remove [] because it gives me a string and commas – sdavb Nov 19 '20 at 00:49
@sdavb That's how Java prints out a list by default. See this answer for possible next steps: https://stackoverflow.com/a/22577565/7916438 – tevemadar Nov 19 '20 at 13:47

In list find lenghtOfArgument with lambda in Java

2 Answers2