Arraylist of arraylist

ArrayList

// THIS IS OKAY:
ArrayList arrayList = new ArrayList();

Source: dummies.com

Arraylist of arraylist

public static void main(String[] args) {
    ArrayList<ArrayList<Integer>> outer = new ArrayList<ArrayList<Integer>>();
    ArrayList<Integer> inner = new ArrayList<Integer>();        

    inner.add(100);     
    inner.add(200);
    outer.add(inner); // add first list
    inner = new ArrayList<Integer>(inner); // create a new inner list that has the same content as  
                                           // the original inner list
    outer.add(inner); // add second list

    outer.get(0).add(300); // changes only the first inner list

    System.out.println(outer);
}

Source: stackoverflow.com

Similar codes

1 vote323 views1 answer
Validate date java
Java
0 vote375 views1 answer
Spring commandlinerunner example
Java
3 votes344 views5 answers
String to int array java
Java
0 vote322 views1 answer
Android studio how to move a picture canvas
Java
1 vote326 views1 answer
Get value textfield java
Java
34 votes324 views6 answers
Java declare array
Java
5 votes309 views2 answers
Add to list java
Java
0 vote356 views1 answer
How to create space between element in vbox in javafx
Java
1 vote334 views1 answer
How to destroy activity in android
Java
4 votes334 views2 answers
Spigot cancel repeating task
Java