CODEWITHSUNDEEP
javaarraysarraylist
jojo
jojo

Reputation: 13

How to create an ArrayList of arrays of Objects in Java?

I was wondering how exactly to create an ArrayList of an array of objects. For example

Object[] objectArray = new Object() // Varying amount of object[]

I would like to add Object[] to an ArrayList as they come in. I have seen that an ArrayList of arrays can be created by the following: 

ArrayList<String[]> action = new ArrayList<String[]>();

So I was thinking it would be as simple as:

ArrayList<objectArray[]> action = new ArrayList<objectArray[]>();

But apparently not.

Upvotes: 0

Views: 132

Answers (5)

Bruno Rodrigues Alcantara
Bruno Rodrigues Alcantara

Reputation: 23

It's a easy stuff.

// Class Student with a attribute name
public class Student{
    String name;
    public Student(String name){
        this.name = name;
    }

    public String getName(){
        return this.name;
    }


public static void main(String[] args) {
    // Creating an ArrayList for Students
    ArrayList<Student> students = new ArrayList<Student>();

    // Creating an Students Objects
    Student a1 = new Student("Name1");
    Student a2 = new Student("Name2");
    Student a3 = new Student("Name3");

    // Populating ArrayList<Student>
    students.add(a1);
    students.add(a2);
    students.add(a3);

    // For Each to sweeping all objects inside of this ArrayList
    for(Student student : students){
        System.out.println(student.getName());
    }
}

Enjoy!

Upvotes: 0

MaxHeap
MaxHeap

Reputation: 1146

So, you have two questions: 

Object[] objectArray = new Object() 
ArrayList<objectArray[]> action = new ArrayList<objectArray[]>();

Change it to:

int MAX_ARRAY = 3;
Object[] objectArray = new Object[MAX_ARRAY];

ArrayList<Object[]> action = new ArrayList<Object[]>();

Now you can add your objectArray to "action":

action.add(objectArray);

Upvotes: 0

M A
M A

Reputation: 72844

The type parameter in the generic List class should be the class name and not the name of the variable that references the array:

ArrayList<Object[]> action = new ArrayList<Object[]>();

Two notes:

  1. Try to avoid declaring types to the implementations. Declare action as a List (the interface):

    List<Object[]> action = new ArrayList<Object[]>();

  2. It would make life a bit easier if you make the parameter another List instead of an array of Objects:

    List<List<?>> action = new ArrayList<List<?>>();

Upvotes: 1

user153
user153

Reputation: 146

ArrayList<LoadClass[]> sd = new ArrayList<LoadClass[]>();

This works :)

Upvotes: 0

Eran
Eran

Reputation: 393781

You create an ArrayList of arrays this way :

ArrayList<Object[]> action = new ArrayList<Object[]>();

Each time you add an Object[] to that list, it must have a fixed length. If you want variable length arrays inside the ArrayList, I suggest you use ArrayList<ArrayList<Object>>.

Your syntax with objectArray is simply not valid Java syntax.

Upvotes: 2

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