Groovy: Clone map

'clone()' method is used to get the copy of a map.

HelloWorld.groovy

def map1 = [
 simpleType : 123,
 complexType : [a : 1, b : 2],
 boolType : true,
]

def map2 = map1.clone()

println "Elements of map1 are"
printMap(map1)

println "\nElements of map2 are"
printMap(map2)

void printMap(map){
 map.each { entry ->
  println "key: $entry.key, value: $entry.value"
 }
}

Output

Elements of map1 are

key: simpleType value: 123

key: complexType value: [a:1, b:2]

key: boolType value: true

Elements of map2 are

key: simpleType value: 123

key: complexType value: [a:1, b:2]

key: boolType value: true

'clone' method returns a shallow copy. If you would like to know more about shallow copy, I would recommend you to go through my below tutorial.

https://self-learning-java-tutorial.blogspot.com/2014/07/shallow-copy-and-deep-copy.html

HelloWorld.groovy

def map1 = [
 simpleType : 123,
 complexType : [a : 1, b : 2],
 boolType : true,
]

def map2 = map1.clone()

println "Elements of map1 are"
printMap(map1)

println "\nElements of map2 are"
printMap(map2)

println "\nAdding two more keys to the map\n"

map2.get('complexType').put('c', 13)
map2.get('complexType').put('d', 14)

println "Elements of map1 are"
printMap(map1)

println "\nElements of map2 are"
printMap(map2)

void printMap(map){
 map.each { entry ->
  println "key: $entry.key, value: $entry.value"
 }
}

Output

Elements of map1 are

key: simpleType, value: 123

key: complexType, value: [a:1, b:2]

key: boolType, value: true

Elements of map2 are

key: simpleType, value: 123

key: complexType, value: [a:1, b:2]

key: boolType, value: true

Adding two more keys to the map

Elements of map1 are

key: simpleType, value: 123

key: complexType, value: [a:1, b:2, c:13, d:14]

key: boolType, value: true

Elements of map2 are

key: simpleType, value: 123

key: complexType, value: [a:1, b:2, c:13, d:14]

key: boolType, value: true

As you see the final output, Since clone method performs shallow copy, updates done to the complexType of map2 object are reflected to map1 also.

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