I am trying to write a logic to find the quickest route, the input is given in format "1-2-30#2-3-25#3-4-30#..." which means from station 1 to 2 it will take 30 minutes. In this code when i am recursively calling searchMapKey() function, if the key is not present, then i am getting execption "Exception in thread "main" java.util.ConcurrentModificationException"
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
import java.util.StringTokenizer;
public class QuickestRoute {
static int totalWeight = 0;
public static String outpit;
public static void main(String[] args) {
// TODO Auto-generated method stub
String input1[] = { "1-2-30#2-3-25#3-4-30#4-5-45#5-6-30#6-7-15#7-8-60#8-9-40",
"10-11-45#11-4-60#4-12-60#12-13-45#13-14-30#14-15-35",
"1-3-40#3-4-25#4-16-30#16-17-15#17-18-20#18-19-30#19-20-25", "21-12-30#12-17-180#17-22-45" }; };
String input2 = "12#18";
String[] output = quickestMetroRoute(input1, input2);
/*
* for(int i=0;i<output.length;i++) System.out.println(output[i]);
*/
}
public static String[] quickestMetroRoute(String[] input1, String input2) {
// Write code here
Map<String, Integer> input = new HashMap<String, Integer>();
for (int i = 0; i < input1.length; i++) {
StringTokenizer str = new StringTokenizer(input1[i], "#");
while (str.hasMoreTokens()) {
String[] parts = str.nextToken().split("-");
String node = parts[0] + "-" + parts[1];
int weight = Integer.parseInt(parts[2]);
input.put(node, weight);
}
}
Map<String, Integer> sortedMap = sortByValue(input);
System.out.println(Collections.singletonList(sortedMap));
String[] parts = input2.split("#");
String source = parts[0];
String destination = parts[1];
searchMapKey(source, destination, sortedMap);
/*
* for (Map.Entry<String, Integer> entry : input.entrySet()) { String
* key = entry.getKey(); Integer value = entry.getValue(); // ... }
*/
System.out.println("outpit: " + outpit);
System.out.println("totalWeight: " + totalWeight);
return input1;
}
private static void searchMapKey(String source, String destination, Map<String, Integer> input) {
// TODO Auto-generated method stub
for (Iterator<Entry<String, Integer>> it = input.entrySet().iterator(); it.hasNext();) {
Entry<String, Integer> entry = it.next();
String key = entry.getKey();
Integer value = entry.getValue();
// ...
String[] nodeParts = key.split("-");
String nodeFirst = nodeParts[0];
String nodeSecond = nodeParts[1];
if (nodeFirst.equals(source)) {
totalWeight += value;
outpit += key;
if (destination.equals(nodeSecond)) {
totalWeight += value;
outpit += key;
return;
} else {
input.remove(key);
searchMapKey(nodeSecond, destination, input);
}
}
if (nodeSecond.equals(source)) {
totalWeight += value;
outpit += key;
if (destination.equals(nodeFirst)) {
totalWeight += value;
outpit += key;
return;
} else {
input.remove(key);
searchMapKey(nodeFirst, destination, input);
}
}
}
}
private static Map<String, Integer> sortByValue(Map<String, Integer> unsortMap) {
// 1. Convert Map to List of Map
List<Map.Entry<String, Integer>> list =
new LinkedList<Map.Entry<String, Integer>>(unsortMap.entrySet());
// 2. Sort list with Collections.sort(), provide a custom Comparator
// Try switch the o1 o2 position for a different order
Collections.sort(list, new Comparator<Map.Entry<String, Integer>>() {
public int compare(Map.Entry<String, Integer> o1,
Map.Entry<String, Integer> o2) {
return (o1.getValue()).compareTo(o2.getValue());
}
});
// 3. Loop the sorted list and put it into a new insertion order Map LinkedHashMap
Map<String, Integer> sortedMap = new LinkedHashMap<String, Integer>();
for (Map.Entry<String, Integer> entry : list) {
sortedMap.put(entry.getKey(), entry.getValue());
}
/*
//classic iterator example
for (Iterator<Map.Entry<String, Integer>> it = list.iterator(); it.hasNext(); ) {
Map.Entry<String, Integer> entry = it.next();
sortedMap.put(entry.getKey(), entry.getValue());
}*/
return sortedMap;
}
}
try this code i have made 2 modifications
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
import java.util.StringTokenizer;
public class QuickestRoute {
static int totalWeight = 0;
public static String outpit;
public static void main(String[] args) {
// TODO Auto-generated method stub
String input1[] = { "1-2-30#2-3-25#3-4-30#4-5-45#5-6-30#6-7-15#7-8-60#8-9-40",
"10-11-45#11-4-60#4-12-60#12-13-45#13-14-30#14-15-35",
"1-3-40#3-4-25#4-16-30#16-17-15#17-18-20#18-19-30#19-20-25", "21-12-30#12-17-180#17-22-45" };
String input2 = "12#18";
String[] output = quickestMetroRoute(input1, input2);
/*
* for(int i=0;i<output.length;i++) System.out.println(output[i]);
*/
}
public static String[] quickestMetroRoute(String[] input1, String input2) {
// Write code here
Map<String, Integer> input = new HashMap<String, Integer>();
for (int i = 0; i < input1.length; i++) {
StringTokenizer str = new StringTokenizer(input1[i], "#");
while (str.hasMoreTokens()) {
String[] parts = str.nextToken().split("-");
String node = parts[0] + "-" + parts[1];
int weight = Integer.parseInt(parts[2]);
input.put(node, weight);
}
}
Map<String, Integer> sortedMap = sortByValue(input);
System.out.println(Collections.singletonList(sortedMap));
String[] parts = input2.split("#");
String source = parts[0];
String destination = parts[1];
searchMapKey(source, destination, sortedMap);
/*
* for (Map.Entry<String, Integer> entry : input.entrySet()) { String
* key = entry.getKey(); Integer value = entry.getValue(); // ... }
*/
System.out.println("outpit: " + outpit);
System.out.println("totalWeight: " + totalWeight);
return input1;
}
private static void searchMapKey(String source, String destination, Map<String, Integer> input) {
// TODO Auto-generated method stub
ArrayList<Map<String, Integer>> removeList = new ArrayList<Map<String, Integer>>();
for (Iterator<Entry<String, Integer>> it = input.entrySet().iterator(); it.hasNext();) {
Entry<String, Integer> entry = it.next();
String key = entry.getKey();
Integer value = entry.getValue();
// ...
String[] nodeParts = key.split("-");
String nodeFirst = nodeParts[0];
String nodeSecond = nodeParts[1];
if (nodeFirst.equals(source)) {
totalWeight += value;
outpit += key;
if (destination.equals(nodeSecond)) {
totalWeight += value;
outpit += key;
return;
} else {
it.remove();
// input.remove(key);
Map<String, Integer> next = new HashMap<String, Integer>();
next.putAll(input);
searchMapKey(nodeSecond, destination, next);
}
}
if (nodeSecond.equals(source)) {
totalWeight += value;
outpit += key;
if (destination.equals(nodeFirst)) {
totalWeight += value;
outpit += key;
return;
} else {
it.remove();
// input.remove(key);
Map<String, Integer> next = new HashMap<String, Integer>();
next.putAll(input);
searchMapKey(nodeFirst, destination, next);
}
}
}
}
private static Map<String, Integer> sortByValue(Map<String, Integer> unsortMap) {
// 1. Convert Map to List of Map
List<Map.Entry<String, Integer>> list = new LinkedList<Map.Entry<String, Integer>>(unsortMap.entrySet());
// 2. Sort list with Collections.sort(), provide a custom Comparator
// Try switch the o1 o2 position for a different order
Collections.sort(list, new Comparator<Map.Entry<String, Integer>>() {
public int compare(Map.Entry<String, Integer> o1, Map.Entry<String, Integer> o2) {
return (o1.getValue()).compareTo(o2.getValue());
}
});
// 3. Loop the sorted list and put it into a new insertion order Map
// LinkedHashMap
Map<String, Integer> sortedMap = new LinkedHashMap<String, Integer>();
for (Map.Entry<String, Integer> entry : list) {
sortedMap.put(entry.getKey(), entry.getValue());
}
/*
* //classic iterator example for (Iterator<Map.Entry<String, Integer>>
* it = list.iterator(); it.hasNext(); ) { Map.Entry<String, Integer>
* entry = it.next(); sortedMap.put(entry.getKey(), entry.getValue()); }
*/
return sortedMap;
}
}
your output
[{6-7=15, 16-17=15, 17-18=20, 19-20=25, 2-3=25, 3-4=25, 18-19=30, 13-14=30, 4-16=30, 1-2=30, 21-12=30, 5-6=30, 14-15=35, 8-9=40, 1-3=40, 10-11=45, 12-13=45, 17-22=45, 4-5=45, 7-8=60, 4-12=60, 11-4=60, 12-17=180}]
outpit: null21-1212-1313-1414-154-124-1616-1717-1817-1811-410-113-41-31-22-32-31-24-55-66-77-88-912-1717-1817-18
totalWeight: 975
you are using a recursive function and removing elements in an iterator and again in another call working with them, what i have done is for each time you remove an element, make a copy of it and then forward it to the proceeding recursive call feel free to ask if it doesn't clears