- Classical way of iterating a map
Syntax :
for(Map.Entry entry : map.entrySet){
entry.getKey()
entry.getValue()
example :
private static void oldMapIter(Map map) {
for(Map.Entry entry : map.entrySet()) {
System.out.println(entry.getKey() + ":" + entry.getValue());
}
}
We can simply use Lambda expressions to get this done.
private static void newMapIter(Map map) {
// map.forEach((k,v)->System.out.println("newMapIter()."+k+" : " + v ));
map.forEach((k,v)->{
System.out.println(k+" : "+v );
});
}
2. Classical way of iterating a map
private static void oldCollection(List list) {
for (String string : list) {
System.out.println(string);
}
}
Iterate using Lambda expression :
private static void newCollection(List list) {
// list.forEach(item -> System.out.println("newCollection().item : " + item));
list.forEach(item -> {
System.out.println(item);
});
}
But there are some downsides of using Lambda in forEach. One of them is restrictions to use variables inside the block. Because to mutate (increase the index etc) a variable inside the Lambda forEach block, it should be final or effectively final.
Further readiings :
Knowledge Hunter 