Graphs.java

import java.util.ArrayList;

public class Graphs {
	int numArrays;
	static ArrayList[] arr;
	//constructor
	public Graphs(int numArrays) {
		this.numArrays = numArrays;
		arr = new ArrayList[numArrays];
		
		for(int i = 0;i< arr.length;i++) {
			arr[i] = new ArrayList<Integer>();
		}
		
	}
	
	public static void main(String[]args) {
		Graphs g = new Graphs(5);
		g.addEdge(0, 1);
		g.addEdge(0, 4);
		g.addEdge(1, 2);
		g.addEdge(1, 3);
		g.addEdge(1, 4);
		g.addEdge(2, 3);
		g.addEdge(2, 4);
		
		for(int i = 0;i<arr.length;i++) {
			System.out.println(getEdge(i));
		}
		
	}//end main
	
	public void addEdge(int vertex1, int vertex2) {
		arr[vertex1].add(vertex2);
		arr[vertex2].add(vertex1);
	}//end method
	
	public static String getEdge(int vertex) {
		String str = vertex + " :";
			for(int j = 0;j<arr[vertex].size();j++) {
				//System.out.println(vertex+ " : " + arr[vertex].get(j));
				str += " " + arr[vertex].get(j);
			}
			return str;
	}//end method
}