Getting TLE on this problem. Can someone please help on optimizing the code

general
1

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashSet;
import java.util.StringTokenizer;

public class BertownRoads {
static int MAX;
static ArrayList<HashSet> adj;
static boolean[] visited;
static int in[];
static int low[];
static int timer;
static boolean hasBridge;
static ArrayList<ArrayList> edgeList;

public BertownRoads() {
	MAX = 100001;
	adj = new ArrayList<HashSet<Integer>>(MAX);
	visited = new boolean[MAX];
	in = new int[MAX];
	low = new int[MAX];
	hasBridge = false;
	timer = 0;
	edgeList = new ArrayList<ArrayList<Integer>>();

	for (int i = 0; i < MAX; i++) {
		adj.add(new HashSet<Integer>());
	}
}

void dfs(int node, int par) {
	visited[node] = true;
	in[node] = timer;
	low[node] = timer;
	timer++;
	for (int child : adj.get(node)) {
		if (child == par)
			continue;

		 if (!visited[child]) {
			dfs(child, node);
			if (low[child] > in[node]) {
				hasBridge = true;
				return;
			}
			edgeList.add(new ArrayList<Integer>(Arrays.asList(node, child)));
			low[node] = Math.min(low[node], low[child]);
		}

		else {
			low[node] = Math.min(low[node], in[child]);
			if (in[node] > in[child]) {
				edgeList.add(new ArrayList<Integer>(Arrays.asList(node, child)));
			}

		}
	}
}

public static void main(String[] args) throws IOException {
	BufferedReader read = new BufferedReader(new InputStreamReader(System.in));
	int n, m = 0, a, b;
	StringTokenizer st = new StringTokenizer(read.readLine(), " ");
	while (st.hasMoreTokens()) {
		n = Integer.parseInt(st.nextToken());
		m = Integer.parseInt(st.nextToken());
	}

	BertownRoads cc = new BertownRoads();
	for (int i = 0; i < m; i++) {
		st = new StringTokenizer(read.readLine(), " ");
		while (st.hasMoreTokens()) {
			a = Integer.parseInt(st.nextToken());
			b = Integer.parseInt(st.nextToken());
			adj.get(a).add(b);
			adj.get(b).add(a);
		}
	}

	cc.dfs(1, -1);
	if (hasBridge) {
		System.out.println(0);
	} else {
		edgeList.forEach(list -> {
			StringBuilder sb = new StringBuilder();
			list.forEach(x -> sb.append(x).append(" "));
			System.out.println(sb);
		});
	}
}

}