Java - LinkedList of LinkedLists of Type Object

Question

I am declaring a LinkedList of LinkedLists of type GraphEdge as follows:

First declare LinkedList and fixed length (for global numVertices):

LinkedList[] adjList = new LinkedList[numVertices];

Then initialize each adjList[i] as a new LinkedList<GraphEdge>()

for (i = 0; i < this.numVertices; i++) {
    adjList[i] = new LinkedList<GraphEdge>();
}

But I am getting an error when trying to call:

GraphEdge nextEdge = adjList[v].peekFirst();

That is not a LinkedList of LinkedLists - it's an array of LinkedLists. — Jesper
– Jesper, Commented Oct 25, 2015 at 20:04

Kayaman · Accepted Answer · 2015-10-25 20:04:13Z

1

Use a LinkedList<LinkedList<GraphEdge>> instead of an array to preserve the generic type information or add a cast.

GraphEdge nextEdge = (GraphEdge)adjList[v].peekFirst();

The cast is the ugly, bad solution.

answered Oct 25, 2015 at 20:04

Kayaman

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