I am working with Google Guava to use a Multimap like this for example {S1.E11=[S2.E236], S1.E108=[S2.E371]} . But I have a problem. I want to read from file the mapping entities and put them into my Multimap, it's something like indexing with hashmaps. So here's my file mapping.csv:
S1.E10;S2.E235;0.86
S1.E108;S2.E371;0.99
S1.E109;S2.E372;0.99
S1.E11;S2.E236;0.86
S1.E113;S2.E51;0.73
And here's my Java code:
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package indexing;
import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import com.google.common.collect.ArrayListMultimap;
import com.google.common.collect.Multimap;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.Set;
public class Indexing {
public static String getKeyOfValue(String value, Multimap<String, String> multiM) {
String keyOfValue = new String();
Set<String> setKeys = multiM.keySet();
for (String key : setKeys) {
if (multiM.get(key).contains(value)) {
keyOfValue = key;
}
}
return keyOfValue;
}
public static boolean removeValueOfKey(String key, String value, Multimap<String, String> multiM) {
Collection values = multiM.get(key);
for (Iterator<String> iterator = values.iterator(); iterator.hasNext();) {
String element = iterator.next();
if (value.equals(element)) {
values.remove(element);
return true;
}
}
return false;
}
/*e0 devient representant de e1*/
public static void caseRptRpt(String e0, String e1, Multimap<String, String> multiM) {
multiM.put(e0, e1);
Collection values;
//marquer e0 comme representant de e1
values = multiM.get(e1);
for (Iterator<String> iterator = values.iterator(); iterator.hasNext();) {
String element = iterator.next();
//marquer les representées par e1 comme represetées par e0
multiM.put(e0, element);
}
//supprimer e1 des representants avec ses representées
multiM.removeAll(e1);
}
public static void main(String[] args) throws IOException {
// TODO code application logic here
Multimap<String, String> multiMap = ArrayListMultimap.create();
BufferedReader br = new BufferedReader(new FileReader("mapping.csv"));
String line = null;
String[] tabLine;
String[][] array = new String[5][5];
try {
while (((line = br.readLine()) != null)) {
line = br.readLine();
//line = line.trim();
tabLine = line.split(";");
//System.out.print(tabLine[0]);
//System.out.print(" ");
//System.out.println(tabLine[1]);
if (!multiMap.isEmpty()) {
//si e0 est representant et e1 est representant
if (multiMap.containsKey(tabLine[0]) && multiMap.containsKey(tabLine[1])
&& !(multiMap.containsValue(tabLine[0]) || multiMap.containsValue(tabLine[1]))) {
//e1 devient representant de e0
caseRptRpt(tabLine[1], tabLine[0], multiMap);
} //si e0 est representant et e1 est representé par une entité e
else if (multiMap.containsKey(tabLine[0]) && multiMap.containsValue(tabLine[1])
&& !(multiMap.containsValue(tabLine[0]) || multiMap.containsKey(tabLine[1]))
&& !(multiMap.containsEntry(tabLine[0], tabLine[1]))) {
//marquer e1 comme representé par e0
multiMap.put(tabLine[0], tabLine[1]);
//supprimer e1 des representées par l'entité e
removeValueOfKey(getKeyOfValue(tabLine[1], multiMap), tabLine[1], multiMap);
} //sinon si e0 est representé par e et e1 est representant mais ne contient pas e0 comme representé
else if (multiMap.containsValue(tabLine[0]) && multiMap.containsKey(tabLine[1])
&& !(multiMap.containsKey(tabLine[0]) || multiMap.containsValue(tabLine[1]))
&& !(multiMap.containsEntry(tabLine[1], tabLine[0]))) {
//marquer e0 representé par e1
multiMap.put(tabLine[1], tabLine[0]);
removeValueOfKey(getKeyOfValue(tabLine[0], multiMap), tabLine[0], multiMap);
} // si e0 et e1 sont representées par des entitées diff
else if (multiMap.containsValue(tabLine[0]) && multiMap.containsValue(tabLine[1])
&& !(multiMap.containsKey(tabLine[0]) || multiMap.containsKey(tabLine[1]))
&& !(getKeyOfValue(tabLine[0], multiMap).equals(getKeyOfValue(tabLine[1], multiMap)))) {
//marquer e0 comme representé par e1
multiMap.put(getKeyOfValue(tabLine[1], multiMap), tabLine[0]);
removeValueOfKey(getKeyOfValue(tabLine[0], multiMap), tabLine[0], multiMap);
} //else if (multiMap.isEmpty()) {
//multiMap.put(tabLine[0], tabLine[1]);
//}
} else {
multiMap.put(tabLine[0], tabLine[1]);
}
}
} catch (Exception e) {
System.err.println("Error: " + e);
e.printStackTrace();
}
//to here
System.out.println(multiMap);
}
}
When I run it here's what I got :
run:
Error: java.lang.NullPointerException
java.lang.NullPointerException
at indexing.Indexing.main(Indexing.java:74)
{S1.E108=[S2.E371]}
BUILD SUCCESSFUL (total time: 0 seconds)
So it seems like it does not read the lines properly or something is wrong in my long if-else statement, so that the 2nd line is null. Any help or suggestions please? Thanks in advance.
Why are you calling readLine() inside the while loop?
while (((line = br.readLine()) != null)) {
line = br.readLine();
When you call readLine() and it is not null, the line would have been read into line variable. Then inside the while loop you are making a second call to readLine(). This second call may result in null (ie. end of stream or file).