How to convert List into a List>?

Question

I'm capturing parameters from a request url using com.apache.http.NameValuePair which basically store those params in a List<NameValuePair>. To do certain checks and verifications on those params, I need to convert that list into a List<Map.Entry<String, String>>. Is there a way to do this conversion?

something like this:

http://127.0.0.1:9898/v3/{project_id}/eip/publicips?fields=id&fields=owner

from How to convert List<NameValuePair> into a hashMap<String, String>?

Map<String, String> mapped = list.stream().collect(
        Collectors.toMap(NameValuePair::getName, NameValuePair::getValue));

It is not work for me. because there are many fields key.

Some code or example would be helpful – PatrickChen May 29 '20 at 03:41 — PatrickChen, May 29 '20 at 03:41
What have you tried so far? – RubioRic May 29 '20 at 03:47 — RubioRic, May 29 '20 at 03:47

score 3 · Accepted Answer · answered May 29 '20 at 04:07

3

You can convert each NameValuePair into Map.Entry and then collect them into List

List<Map.Entry<String, String>> entries = list.stream()
                                              .map(n->new AbstractMap.SimpleEntry<String, String>(n.getName(), n.getValue())
                                              .collect(Collectors.toList());

answered May 29 '20 at 04:07

Ryuzaki L

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I need to stop hurrying – Vikas May 29 '20 at 05:42

score 0 · Answer 2 · answered May 29 '20 at 04:39

Probably you've messed something else that's not included in the code excerpt. I've tried to reproduce your case and it works in my setup.


public class Main {

    public static void main(String[] args) {
        List<NameValuePair> list = new ArrayList<>();
        MyNameValuePair myNameValuePair = new MyNameValuePair();
        myNameValuePair.setKvKey("i");
        list.add(myNameValuePair);
        myNameValuePair = new MyNameValuePair();
        myNameValuePair.setKvKey("j");
        list.add(myNameValuePair);
        myNameValuePair = new MyNameValuePair();
        myNameValuePair.setKvKey("k");
        list.add(myNameValuePair);
        Map<String, String> mapped = new HashMap<>();
        mapped = list.stream().collect(
                Collectors.toMap(NameValuePair::getName, NameValuePair::getValue));

        System.out.println(mapped);
    }
}

class MyNameValuePair implements NameValuePair {
    private String kvKey;
    public void setKvKey(String kvKey){
        this.kvKey = kvKey;
    }

    @Override
    public String getName() {
        return kvKey;
    }

    @Override
    public String getValue() {
        return "val";
    }
}

How to convert List into a List>?

2 Answers2