A really, really simple depth first search implementation.

DepthFirstSearch.java

import java.util.Arrays;

public class DepthFirstSearch {
  public static void main(String[] args) {
    int[][] graph = { 
      { 0, 1, 2 },
      { 0, 1, 2 },
      { 0, 1, 2 },
    };  
    boolean[] found = new boolean[ graph[0].length ];   

    DepthFirstSearch.DFS(graph, 0, found);

    System.out.println(Arrays.toString(found));
  }

  public static void DFS(int[][] g, int v, boolean[] found) {
    found[v] = true;    

    for (int w: g[v]) {
      if (!found[w]) {
        DFS(g, w, found);
      }   
    }   
  }
}