user9569944 :
In this java assignment we have a for loop that reads through a text file we use in this program, and we are supposed to replace it with a stream. Here is part of the program and what we are supposed to replace:
import java.io.FileNotFoundException;
import java.util.List;
import java.util.Map;
import java.util.TreeMap;
public class FrequentWords {
public static void main(String[] args) throws FileNotFoundException {
String filename = "SophieSallyJack.txt";
if (args.length == 1) {
filename = args[0];
}
Map<String, Integer> wordFrequency = new TreeMap<>();
List<String> incoming = Utilities.readAFile(filename);
// TODO replace the following loop with a single statement using streams
// that populates wordFrequency
for (String word : incoming) {
word = word.toLowerCase();
if (!"".equals(word.trim())) {
Integer cnt = wordFrequency.get(word);
if (cnt == null) {
wordFrequency.put(word, 1);
} else {
int icnt = cnt + 1;
wordFrequency.put(word, icnt);
}
}
}
I have tried this and I can't seem to figure out anything else:
incoming.stream()
.collect(Collectors.toMap(word -> word, word -> 1, Integer::sum)).entrySet();
Shubhendu Pramanik :
Here's what you can try:
wordFrequency = incoming.stream()
.map(String::toLowerCase).filter(word -> !word.trim().isEmpty())
.collect(Collectors.toMap
(word -> word, word -> 1, (a, b) -> a + b, TreeMap::new));
You missed the BinaryOperator
that will merge values of the key
already exists Collectors.toMap()