How to Convert/add String Array[] elements into List<String> [] Array

JavaLearn :

I have three arrays of String

String array1 [] = {"A", "B", "C"};
String array2 [] = {"D", "E"};
String array3 [] = {"F", "G", "H", "I"};

I want to store all this arrays into List of String array.

List<String> allArrays[]

My output List allArrays[] should contain

allArrays[0]= [A,B,C]
allArrays[1]= [D,E]
allArrays[2]= [F,G,H,I]

I have tried below piece of code but getting null pointer exception

String array1 [] = {"A", "B", "C"};
String array2 [] = {"D", "E"};
String array3 [] = {"F", "G", "H", "I"};

List<String> allArrays[] =null;

allArrays[0].addAll(Arrays.asList(array1));
//Null pointer exception here
allArrays[1].addAll(Arrays.asList(array2));
allArrays[2].addAll(Arrays.asList(array3));

System.out.println(b[0]);
System.out.println(b[1]);
System.out.println(b[2]);

Majed Badawi :

You are not creating and adding to the list correctly. Since you need an array of List<String>, you can do this:

String array1 [] = {"A", "B", "C"};
String array2 [] = {"D", "E"};
String array3 [] = {"F", "G", "H", "I"};
List<String>[] allArrays = new ArrayList[3]; 

List<String> list = new ArrayList<String>();
Collections.addAll(list, array1);
allArrays[0] = list;
list = new ArrayList<String>();
Collections.addAll(list, array2);
allArrays[1] = list;
list = new ArrayList<String>();
Collections.addAll(list, array3);
allArrays[2] = list;
        
System.out.println(allArrays[0]);
System.out.println(allArrays[1]);
System.out.println(allArrays[2]);

Output:

[A, B, C]
[D, E]
[F, G, H, I]

A better way would be using List<List<String>>:

String array1 [] = {"A", "B", "C"};
String array2 [] = {"D", "E"};
String array3 [] = {"F", "G", "H", "I"};
List<List<String>> allArrays = new ArrayList<>(); 

allArrays.add(Arrays.asList(array1));
allArrays.add(Arrays.asList(array2));
allArrays.add(Arrays.asList(array3));
                
System.out.println(allArrays);

Output: