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loopsgroovy

Get next iterator value in Groovy

How can I get the next value of iterator while looping through a collection with Groovy 1.7.4

values.each {it ->
    println(it)
    println(it.next()) //wrong
}
Solution

  • So if you want to check the next item in the list (assuming it's a list), you can do:

    // Given a list:
def values = [ 1, 2, 3, 4 ]

// Iterate through it, printing out current and next value:
for( i = 0 ; i < values.size() ; i++ ) {
    def curr = values[ i ]
    def next = i < values.size() - 1 ? values[ i + 1 ] : null
    println( "$curr $next" )
}

    Or, you can use inject to store the previous value, and get:

    values[ 1..-1 ].inject( values[ 0 ] ) { prev, curr ->
    println "$prev $curr"
    curr
}

    Or, you can just keep track of the previous element yourself with an each:

    def prev = null
values.each { curr ->
  if( prev != null ) println "$prev $curr"
  prev = curr
}