Java 8 apply function to all elements of Stream without breaking stream chain

Question

Is there a way in Java to apply a function to all the elements of a `Stream` without breaking the `Stream` chain? I know I can call `forEach`, but that method returns a `void`, not a `Stream`.

Accepted Answer

There are (at least) 3 ways. For the sake of example code, I've assumed you want to call 2 consumer methods `methodA` and `methodB`:

A. Use `peek()`:

```
list.stream().peek(x -> methodA(x)).forEach(x -> methodB(x));
```

Although the docs say only use it for "debug", it works (and it's in production right now)

B. Use `map()` to call methodA, then return the element back to the stream:

```
list.stream().map(x -> {method1(x); return x;}).forEach(x -> methodB(x));
```

This is probably the most "acceptable" approach.

C. Do two things in the `forEach()`:

```
list.stream().forEach(x -> {method1(x); methodB(x);});
```

This is the least flexible and may not suit your need.

Java 8 apply function to all elements of Stream without breaking stream chain

Solution

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