How to create and initialise in Java an array of String arrays in one line?-CodePudding

Let's say I have in Java 8 the following objects defined:

String[] filledArr = new String[] {"Hallo"};
String[] moreFilledArr = new String[] {"Hallo", "duda"};
String[] emptyArr = new String[] {};

Now I want to create an array containing these two string arrays. How do I write this?

I tried:

String[][] = {emptyArr, filledArr, moreFilledArr};

This doesn't work. Then I tried:

(String[])[] = {emptyArr, filledArr, moreFilledArr};

With the brackets in the second version I want to indicate that the array is one of string arrays and not a two-dimensional array. Still no success.

What's the correct way to do it? Is there one? Or do I have to resort to ImmutableList to create an immutable data-structure here.

CodePudding user response：

You have forgotten to give the variable a name? Both of these work.

String[][] array = {emptyArr, filledArr, moreFilledArr};

String[][] array = new String[][] {emptyArr, filledArr, moreFilledArr};

I recommend you to go through the basic Java syntax specification and tutorials. Start with The Java Tutorials by Oracle Corp, free of cost.

CodePudding user response：

these two are right too String[][] array = {emptyArr, filledArr, moreFilledArr};

String[][] array = new String[][] {emptyArr, filledArr, moreFilledArr};

please do check these too Docs for Array in Java Have a Look for more clarification
tutorial of array with java docs ,

I had to add this as a comment but I couldn't, I want to extend with more resources mentioned above , Thanks

CodePudding user response：

We can also achieve it by initialising and assigning to a single dimensional array of type Object. Something like below.

    String[] filledArr = new String[] {"Hallo"};
    String[] moreFilledArr = new String[] {"Hallo", "duda"};
    String[] emptyArr = new String[] {};

    Object[] newArr = {filledArr, moreFilledArr, emptyArr};

If you want to print the values inside this newArr, then you shall use the below code.

for (int i=0;i< newArr.length; i  ){
        Arrays.stream(((String[]) newArr[i])).forEach(System.out::println);
    }