Java – shortcut for creating a Map from a List in groovy

collectionsexpandometaclassgroovyjava

I'd like some sorthand for this:

Map rowToMap(row) {
    def rowMap = [:];
    row.columns.each{ rowMap[it.name] = it.val }
    return rowMap;
}

given the way the GDK stuff is, I'd expect to be able to do something like:

Map rowToMap(row) {
    row.columns.collectMap{ [it.name,it.val] }
}

but I haven't seen anything in the docs… am I missing something? or am I just way too lazy?

Best Solution

I've recently came across the need to do exactly that: converting a list into a map. This question was posted before Groovy version 1.7.9 came out, so the method collectEntries didn't exist yet. It works exactly as the collectMap method that was proposed:

Map rowToMap(row) {
    row.columns.collectEntries{[it.name, it.val]}
}

If for some reason you are stuck with an older Groovy version, the inject method can also be used (as proposed here). This is a slightly modified version that takes only one expression inside the closure (just for the sake of character saving!):

Map rowToMap(row) {
    row.columns.inject([:]) {map, col -> map << [(col.name): col.val]}
}

The + operator can also be used instead of the <<.

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