CODEWITHSUNDEEP
groovy
Ethyl Casin
Ethyl Casin

Reputation: 793

subtract List by objid

I have this code in Groovy:

def list1 = [[objid:1, name:"One"], [objid:2, name:"Two"]];
def list2 = [[objid:2, name:"Hello"]];
def list3 = list1 - list2;

println list3;

The output of the code above will result something like this:

[[objid:1, name:One], [objid:2, name:Two]]

QUESTION: How to subtract List by objid? I want the result to be something like this: [[objid:1, name:One]] since objid:2 is present in the List1. How to code it?

Upvotes: 1

Views: 102

Answers (3)

Blank
Blank

Reputation: 12378

You may need a function, try this:

def list1 = [[objid:1, name:"One"], [objid:2, name:"Two"]];
def list2 = [[objid:2, name:"Hello"]];

​​def subtract (list1, list2) {
    def retlist = [];
    if (list1 == null || list2 == null) {
        return null;
    }

    for(test1 in list1) {
        def exists = false;
        for (test2 in list2) {
            exists = (test1.objid == test2.objid) || exists;
        }
        if (!exists) {
            retlist.push(test1);
        }
    }
    return retlist;
}

def list3 = subtract(list1 ,list2)​​;

println list3;​

Upvotes: 2

Nathan Hughes
Nathan Hughes

Reputation: 96394

Given

list1 = [[objid:1, name:"One"], [objid:2, name:"Two"]]
list2 = [[objid:2, name:"Hello"]]

In order to get list1 entries with entries matching objids from list2 filtered out, collect the ids that need to be subtracted into a set, then construct a predicate that tests that the id of the given object isn't in that set:

ids = list2.collect { it['objid'] } as Set
list3 = list1.findAll { !ids.contains(it['objid']) }

(Using a set instead of a list should make the lookups faster.)

The result is that list3 contains:

[[objid:1, name:One]]

Upvotes: 2

gotnull
gotnull

Reputation: 27214

You'll want a function that does the following:

class Foo
{
    public String Name;
    public Integer Id;
}

public Foo getObjId(int id) {
    for (Foo foo : list) {
      if (foo.getId() == id) {
        return foo; // foo bar!
      }
    }
    return null; // foo bar not found.
}

Upvotes: 1

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