Groovy: Iterating over maps

Groovy provides each, eachWithIndex methods to iterate over the map.

Using each method

'each' method is available in two forms.

map.each{entry ->

         println "key: $entry.key, value: $entry.value"

}

map.each{key, value ->

         println "key: $key, value: $value"

}

HelloWorld.groovy

def countryCapitals = ["India" : "new Delhi", "Australia" : "Canberra"]

println "Accessing the data using first type of each method"
countryCapitals.each{entry -> 
 println "CountryName: $entry.key, Capital: $entry.value"
}

println "\nAccessing the data using second type of each method"
countryCapitals.each{country, capital -> 
 println "CountryName: $country, Capital: $capital"
}

Output

Accessing the data using first type of each method

CountryName: India, Capital: new Delhi

CountryName: Australia, Capital: Canberra

Accessing the data using second type of each method

CountryName: India, Capital: new Delhi

CountryName: Australia, Capital: Canberra

Using eachWithIndex method

'eachWithIndex' method is available in two forms.

map.eachWithIndex {entry, i ->

         println "$i : key: $entry.key, value: $entry.value"

}

map.eachWithIndex{key, value, i ->

         println "$i: key: $key, value: $value"

}

Find the below working example.

HelloWorld.groovy

def countryCapitals = ["India" : "new Delhi", "Australia" : "Canberra"]

println "Accessing the data using first type of eachWithIndex method"
countryCapitals.eachWithIndex {entry, i -> 
 println "$i : CountryName: $entry.key, Capital: $entry.value"
}

println "\nAccessing the data using second type of eachWithIndex method"
countryCapitals.eachWithIndex{country, capital, i -> 
 println "$i: CountryName: $country, Capital: $capital"
}

Output

Accessing the data using first type of eachWithIndex method

0 : CountryName: India, Capital: new Delhi

1 : CountryName: Australia, Capital: Canberra

Accessing the data using second type of eachWithIndex method

0: CountryName: India, Capital: new Delhi

1: CountryName: Australia, Capital: Canberra

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