How to get an advanced "for" score?

Question

I was wondering if I could get some kind of control variable, from a for "advanced".

For example:

In a be normal, I do it this way:

 for (int i = 0; i < algumaCoisa.size() ou length; i++){
     //código..
}

this variable i I can use to go through the components, example:

((JComponent) componentes.get(i)).requestFocus();

in a be advanced I would do:

for(MeuComp comp: componentes){
//código..
}

How would I get the position that the for is and traverse all components?

Obs: MeuComp is an interface that contains methods, which are implemented by components such as JTexefield, JComboBox and etc. componentes is a List of these components, but I believe that was not so important, the example may be on top of anything.

Answer 1

It doesn’t. The second example is what’s called foreach and its function is to take each element of a data collection and use it directly. If you want an index use the for simple of the first example, so it is possible to go through all elements and have an index variable. So there are both.

Answer 2

Complementing what @Maniero said, even if you want to get the index, you can do

int index = componentes.indexOf(comp);

This way you get the content of your element. However, if I am not mistaken, it is necessary that your class MeuComp has been equals and hashCode implemented

Answer 3

If you want a functional alternative (Java 8+), yes is also possible. On the Baeldung website you have several examples.

What I came to use was the protopack. So I’m gonna focus on him.

The first thing you need is to import the dependency. If you are using Maven:

<dependency>
    <groupId>com.codepoetics</groupId>
    <artifactId>protonpack</artifactId>
    <version>1.13</version>
</dependency>

Or else Gradle:

implementation com.codepoetics:protonpack:1.13

Or, if not using package manager, put the jar in the classpath (choose a version here).

To use the element with its index, just do the following:

Collection<T> myCollection;

    ...

Stream<Indexed<T>> collectionWithIndexes = StreamUtils
      .zipWithIndex(myCollection.stream());

One of the advantages with the StreamUtils is that you have a Stream from Java 8 to manipulate. The object Indexed<T> has 2 methods of interest: getIndex() and getValue().

You haven’t described how you want to manipulate objects, so I can play any game here. For example, print the content and the hashCode of the elements:

StreamUtils.zipWithIndex(componentes)
  .map(indexedComp  -> indexedComp.getIndex() + ", hash " + indexedComp.getValue().hashCode())
  .forEach(System.out::println);