CODEWITHSUNDEEP
javalambdajava-8
Juru
Juru

Reputation: 1629

First try at lambda

I tried to make my first lambda example but I can't get this simple code to work.

import java.util.ArrayList;
import java.util.function.Predicate;

public class Lambda {

    public static void main(String[] args) {
        final String[] names = {"Wim", "Kian", "Dirk", "Emmanuel", "Frank", "Michaël", "Anna", "Damien", "Alberto"};
        final String[] filteredNames = getNamesWithCriteria(names, (String s) -> s.startsWith("A"));
}

    private String[] getNamesWithCriteria(final String[] names, Predicate<String> predicate) {
        final ArrayList<String> filteredNames = new ArrayList<>();
        for(String name : names) {
            if(predicate.test(name)) {
                filteredNames.add(name);
            }
        }
        return (String[]) filteredNames.toArray();
    }

}

These are the errors that I get:

Lambda.java:8: error: ')' expected
        final String[] filteredNames = getNamesWithCriteria(names, (String s) ->
 s.startsWith("A"));
                                                                          ^
Lambda.java:8: error: illegal start of expression
        final String[] filteredNames = getNamesWithCriteria(names, (String s) ->
 s.startsWith("A"));
                                                                               ^

Lambda.java:8: error: ';' expected
        final String[] filteredNames = getNamesWithCriteria(names, (String s) ->
 s.startsWith("A"));

Upvotes: 0

Views: 120

Answers (2)

Eran
Eran

Reputation: 393791

Here's code that works when compiled with Java 8. Note that all your errors are not related to Java 8 features :

public class Lambda {

    public static void main(String[] args) {
        final String[] names = {"Wim", "Kian", "Dirk", "Emmanuel", "Frank", "Michael", "Anna", "Damien", "Alberto"};
        final String[] filteredNames = getNamesWithCriteria(names, (String s) -> s.startsWith("A"));

    }

    // changed method to be static
    private static String[] getNamesWithCriteria(final String[] names, Predicate<String> predicate) {
        final ArrayList<String> filteredNames = new ArrayList<>();
        for(String name : names) {
            if(predicate.test(name)) {
                filteredNames.add(name);
            }
        }
        // proper conversion to String[]
        return  filteredNames.toArray(new String[filteredNames.size()]);
    }


}

Upvotes: 2

PeterK
PeterK

Reputation: 1723

You are not using Java 8 in your project. It compiled fine here in Java 8. However you have a bug in this line:

return (String[]) filteredNames.toArray();

If you wanted to return an array, change the return statement to this.

return filteredNames.toArray(new String[filteredNames.size()]);

Upvotes: 2

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