Add Listing.setItems(Stream) (#90)

* Add Listings.setItems(Stream)

Fixes vaadin/framework8-issues#447

Change-Id: I4d557d346117d308b80a20effbf5359bebe1e8bb

2 files changed, 50 insertions, 1 deletions

diff --git a/server/src/main/java/com/vaadin/data/Listing.java b/server/src/main/java/com/vaadin/data/Listing.java
index 527c913912..0ecc13b3fb 100644
--- a/server/src/main/java/com/vaadin/data/Listing.java
+++ b/server/src/main/java/com/vaadin/data/Listing.java
@@ -17,7 +17,9 @@ package com.vaadin.data;
 
 import java.io.Serializable;
 import java.util.Collection;
+import java.util.stream.Stream;
 
+import com.vaadin.server.data.BackEndDataProvider;
 import com.vaadin.server.data.DataProvider;
 
 /**
@@ -51,7 +53,7 @@ public interface Listing<T, D extends DataProvider<T, ?>> extends Serializable {
     void setDataProvider(D dataProvider);
 
     /**
-     * Sets the collection of data items of this listing.
+     * Sets the data items of this listing provided as a collection.
      * <p>
      * <strong>Note for component developers: </strong> If the component
      * implementing this interface uses a custom data provider and/or filter
@@ -83,4 +85,27 @@ public interface Listing<T, D extends DataProvider<T, ?>> extends Serializable {
         setDataProvider((D) DataProvider.create(items));
     }
 
+    /**
+     * Sets the data items of this listing provided as a stream.
+     * <p>
+     * This is just a shorthand for {@link #setItems(Collection)}, by
+     * <b>collecting all the items in the stream to a list</b>.
+     * <p>
+     * <strong>Using big streams is not recommended, you should instead use a
+     * lazy data provider.</strong> See {@link BackEndDataProvider} for more
+     * info.
+     * <p>
+     * <strong>Note for component developers: </strong> If the component
+     * implementing this interface uses a custom data provider and/or filter
+     * types, this method should be overridden to provide the same functionality
+     * with the correct data provider type. This might require filter conversion
+     * or a completely custom implementation.
+     *
+     * @param streamOfItems
+     *            the stream of data items to display, not {@code null}
+     */
+    default void setItems(Stream<T> streamOfItems) {
+        setDataProvider((D) DataProvider.create(streamOfItems));
+    }
+
 }
diff --git a/server/src/main/java/com/vaadin/server/data/DataProvider.java b/server/src/main/java/com/vaadin/server/data/DataProvider.java
index ef71378b8f..ad6185b51a 100644
--- a/server/src/main/java/com/vaadin/server/data/DataProvider.java
+++ b/server/src/main/java/com/vaadin/server/data/DataProvider.java
@@ -19,6 +19,7 @@ import java.io.Serializable;
 import java.util.Arrays;
 import java.util.Collection;
 import java.util.Objects;
+import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
 import com.vaadin.server.SerializableFunction;
@@ -168,4 +169,27 @@ public interface DataProvider<T, F> extends Serializable {
     public static <T> ListDataProvider<T> create(T... items) {
         return new ListDataProvider<>(Arrays.asList(items));
     }
+
+    /**
+     * This method creates a new {@link ListDataProvider} from the given stream.
+     * The ListDataProvider <b>collects all the items in the stream to a
+     * list</b>.
+     * <p>
+     * This is just a shorthand for using {@link #create(Collection)} after
+     * collecting the items in the stream to a list with e.g.
+     * {@code stream.collect(Collectors.toList));}.
+     * <p>
+     * <strong>Using big streams is not recommended, you should instead use a
+     * lazy data provider.</strong> See {@link BackEndDataProvider} for more
+     * info.
+     *
+     * @param <T>
+     *            the data item type
+     * @param items
+     *            a stream of data items, not {@code null}
+     * @return a new list data provider
+     */
+    public static <T> ListDataProvider<T> create(Stream<T> items) {
+        return new ListDataProvider<>(items.collect(Collectors.toList()));
+    }
 }