Make arrayList.toArray() return more specific types

The magic of Constructor References (Java 11 feature)

Java 11 has added some colors to our coding life:

List<String> list = new ArrayList<>();
list.add("orange"); // Oranges have Vitamin C!

String[] specificArray = list.toArray(String[]::new); // The *new* way to create an orange pile. 
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Here, we bring more conciseness with compile-time safety. Seems like Java 11 has improved its orange squeezing technique!

Generic Convertor: One method to rule them all!

A generic method can be your swiss army knife for ArrayList to array conversion:

public <T> T[] toArrayCustomType(List<T> list, Class<T> clazz) {
    T[] array = (T[]) Array.newInstance(clazz, list.size());
    return list.toArray(array); // Like converting milk into cheese!
}
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Convert ArrayLists to arrays of any type. It's like having a spell that turns stones into gems!

Coping with Dynamic Types

When the class type is a variable, Array.newInstance() comes as a savior:

Class<?> arrayComponentType = ...; // Depends on your mood maybe?
Object array = Array.newInstance(arrayComponentType, list.size()); // Just like ordering a custom drink.
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Fill it using System.arraycopy() or pal, go with the good-old loop.

Handling common pitfalls

Generics and Casting

When playing with generics, roll your spells right to avoid ClassCastException:

List<?> wildList = new ArrayList<>(Arrays.asList("apple", "banana")); // As wild as wild berries
String[] stringArray = (String[]) wildList.toArray(new String[0]); // Trying not to choke on them
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Robust checks and Error handling

Guard your castle, perform null and empty checks, and always watch out for ArrayStoreException:

if (list != null && !list.isEmpty()) {
    SpecificType[] array = list.toArray(new SpecificType[0]); // Be paranoid! It's better to play safe than sorry.
}
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toString() matters

The toString() method should be overridden in custom classes. It's like, you wouldn't mind having your 🍎 turning into 🍰, would you?

class Custom {
    private String attribute;

    public Custom(String attribute) {
        this.attribute = attribute;
    }

    @Override
    public String toString() {
        return attribute; // Here, we make our apples into apple pies.
    }
}
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The for-each jubilee

for-each loop is your old pal, when it comes to arrays:

for (Custom custom : specificArray) {
    // Play with "custom" as much as you want!
}
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This old cowboy still has some steel left!