Improve Collectors.toMap(Function,Function) error message for duplicate keys #9495
Description
GWT version: 2.8.0
Browser (with version): Chrome 56.0.2924.87 (64-bit)
Operating System: Windows 7
Description
Improve Lambda error messages. Please execute the example i've attached.
What i get running this as GWT, is:
Uncaught Error: java.lang.IllegalStateException: Can't assign multiple values to the same key
at Fm.P [as s] (dmm-0.js:573:12483)
at Fm.T [as v] (dmm-0.js:573:13033)
What i get running this in pure Java, is:
Exception in thread "main" java.lang.IllegalStateException: Duplicate key Item [id=1, name=1-Test]
at java.util.stream.Collectors.lambda$throwingMerger$0(Collectors.java:133)
at java.util.HashMap.merge(HashMap.java:1253)
at java.util.stream.Collectors.lambda$toMap$58(Collectors.java:1320)
The code works fine, i only want highlight that the error message in Pure Java is way better than i GWT. It's much more harder to get behind the error in GWT.
Steps to reproduce
Run the attached Java Class as pure Java application and as GWT application.
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.function.Function;
import java.util.stream.Collectors;
import com.google.gwt.core.client.EntryPoint;
public class TestEntryPoint implements EntryPoint {
public static void main(String[] args) {
new TestEntryPoint().onModuleLoad();
}
@Override
public void onModuleLoad() {
List<Item> items = new ArrayList<>();
items.add(new Item(0, "0-Test"));
items.add(new Item(1, "1-Test"));
items.add(new Item(1, "1-Duplicate"));
Map<Long, Item> map = items.stream().collect(Collectors.toMap(t -> t.id, Function.identity()));
}
public static class Item {
public Long id;
public String name;
public Item(long id, String name) {
this.id = Long.valueOf(id);
this.name = name;
}
@Override
public String toString() {
StringBuilder builder = new StringBuilder();
builder.append("Item [id="); //$NON-NLS-1$
builder.append(this.id);
builder.append(", name="); //$NON-NLS-1$
builder.append(this.name);
builder.append("]"); //$NON-NLS-1$
return builder.toString();
}
}
}