Any way to declare an array in-line

Question

Let s say I have a method m   that takes an array of Strings as an argument   Is there a way I can just declare this array in-line when I make the call   i e  Instead of   String   strs     blah    hey    yo    m strs     Can I just replace this with one line  and avoid declaring a named variable that I m never going to use

User · Answer

You can directly write the array in modern Java, without an initializer. Your example is now valid. It is generally best to name the parameter anyway.

String[] array = {"blah", "hey", "yo"};

or

int[] array = {1, 2, 3};

If you have to inline, you'll need to declare the type:

functionCall(new String[]{"blah", "hey", "yo"});

or use varargs (variable arguments)

void functionCall(String...stringArray) {
    // Becomes a String[] containing any number of items or empty
}

functionCall("blah", "hey", "yo");

Hopefully Java's developers will allow implicit initialization in the future

Update: Kotlin Answer

Kotlin has made working with arrays so much easier! For most types, just use arrayOf and it will implicitly determine type. Pass nothing to leave them empty.

arrayOf("1", "2", "3") // String
arrayOf(1, 2, 3)       // Int
arrayOf(1, 2, "foo")   // Any 
arrayOf<Int>(1, 2, 3)  // Set explict type
arrayOf<String>()      // Empty String array

Primitives have utility functions. Pass nothing to leave them empty.

intArrayOf(1, 2, 3)
charArrayOf()
booleanArrayOf()
longArrayOf()
shortArrayOf()
byteArrayOf()

If you already have a Collection and wish to convert it to an array inline, simply use:

collection.toTypedArray()

If you need to coerce an array type, use:

array.toIntArray()
array.toLongArray()
array.toCharArray()
...

User · Answer

Draemon is correct  You can also declare m as taking varargs   void m String    strs           strs is seen as a normal String   inside the method    m  blah    hey    yo       no    or    needed  each string is a separate arg here

User · Answer

As Draemon says  the closest that Java comes to inline arrays is new String    blah    hey    yo   however there is a neat trick that allows you to do something like  array  blah    hey    yo   with the type automatically inferred   I have been working on a useful API for augmenting the Java language to allow for inline arrays and collection types  For more details google project Espresso4J or check it out here

User · Answer

m new String    blah    hey    yo

User · Answer

I d like to add that the array initialization syntax is very succinct and flexible   I use it a LOT to extract data from my code and place it somewhere more usable   As an example  I ve often created menus like this   Menu menu initMenus menuHandler  new String    File     Save     Load    Edit     Copy            This would allow me to write come code to set up a menu system   The     is enough to tell it to place that item under the previous item   I could bind it to the menuHandler class either by a method naming convention by naming my methods something like  menuFile  menuFileSave  menuFileLoad       and binding them reflectively  there are other alternatives    This syntax allows AMAZINGLY brief menu definition and an extremely reusable  initMenus  method    Yet I don t bother reusing it because it s always fun to write and only takes a few minutes a few lines of code    any time you see a pattern in your code  see if you can replace it with something like this  and always remember how succinct the array initialization syntax is

User · Answer

You can create a method somewhere  public static  lt T gt  T   toArray T    ts        return ts      then use it  m toArray  blah    hey    yo       for better look

User · Answer

Other option is to use ArrayUtils toArray in org apache commons lang3  ArrayUtils toArray  elem1   elem2

User · Answer

Another way to do that  if you want the result as a List inline  you can do it like this   Arrays asList new String      String1    string2

[java] Any way to declare an array in-line?

Update: Kotlin Answer

Examples related to java

Examples related to arrays