for each loop in groovy

Question

How to implement foreach in Groovy? I have an example of code in Java, but I don't know how to implement this code in Groovy...

Java:

for (Object objKey : tmpHM.keySet()) {
   HashMap objHM = (HashMap) list.get(objKey);
}

I read http://groovy.codehaus.org/Looping, and tried to translate my Java code to Groovy, but it's not working.

for (objKey in tmpHM.keySet()) {
   HashMap objHM = (HashMap) list.get(objKey);
}

General note: you will get a lot better answers if you say specifically *what* does not work (no "it's not working"). I just tried, and the loop works. — mabi, Aug 29 '14 at 14:44
A lot of example using loop in grooy here: http://grails.asia/groovy-each-examples — mochadwi, Aug 08 '19 at 15:48

injecteer · Accepted Answer · 2020-07-01T16:23:47.810

111

as simple as:

tmpHM.each{ key, value -> 
  doSomethingWithKeyAndValue key, value
}

edited Jul 01 '20 at 16:23

answered Aug 29 '14 at 14:19

injecteer

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8

Using a closure isn't always the best solution. the .each() approach doesn't allow for break; – Jay Edwards Nov 23 '16 at 11:36
1

this is exactly how the `each` and all other groovy collection methods are built: they just blindnly iterate through one be one. If you need another iteration logic, you must stick with traditional loops – injecteer Nov 24 '16 at 09:40
1

`tmpHM.eachWithIndex{ key, value -> doSomethingWithKeyAndValue() } ` – radbrawler Mar 28 '18 at 09:58
1

@injecteer: you can break if you use `find` and return true. – Bob Stine Aug 07 '19 at 12:12
1

@BobStine it's not really a break. `find` and `each` have totally different purposes – injecteer Aug 07 '19 at 12:14
1

@injecteer your point eludes me. I stand by my statement: the "find" method can be used if you wish to conditionally stop iterating through a collection (aka "break"). – Bob Stine Aug 18 '19 at 14:21
That worked brilliant for my List! – Michelle Feb 07 '22 at 15:06

score 80 · Answer 2 · edited Aug 18 '16 at 14:54

80

This one worked for me:

def list = [1,2,3,4]
for(item in list){
    println item
}

Source: Wikia.

edited Aug 18 '16 at 14:54

Krish Munot

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answered May 04 '15 at 14:55

HumanInDisguise

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score 10 · Answer 3 · edited Jul 20 '21 at 20:04

10

You can use the below groovy code for maps with for-each loop.

def map=[key1:'value1', key2:'value2']

for (item in map) {
  log.info item.value // this will print value1 value2
  log.info item       // this will print key1=value1 key2=value2
}

edited Jul 20 '21 at 20:04

Highway of Life

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answered Aug 30 '17 at 03:09

Gaurav Khurana

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score 1 · Answer 4 · answered Jan 17 '20 at 01:18

Your code works fine.

def list = [["c":"d"], ["e":"f"], ["g":"h"]]
Map tmpHM = [1:"second (e:f)", 0:"first (c:d)", 2:"third (g:h)"]

for (objKey in tmpHM.keySet()) {   
    HashMap objHM = (HashMap) list.get(objKey);
    print("objHM: ${objHM}  , ")
}

prints objHM: [e:f] , objHM: [c:d] , objHM: [g:h] ,

See https://groovyconsole.appspot.com/script/5135817529884672

Then click "edit in console", "execute script"

for each loop in groovy

4 Answers4