1 files changed, 119 insertions, 0 deletions
diff --git a/server/src/main/java/com/vaadin/data/ReadOnlyHasValue.java b/server/src/main/java/com/vaadin/data/ReadOnlyHasValue.java
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+++ b/server/src/main/java/com/vaadin/data/ReadOnlyHasValue.java
@@ -0,0 +1,119 @@
+/*
+ * Copyright 2000-2016 Vaadin Ltd.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not
+ * use this file except in compliance with the License. You may obtain a copy of
+ * the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations under
+ * the License.
+ */
+package com.vaadin.data;
+
+import com.vaadin.server.SerializableConsumer;
+import com.vaadin.shared.Registration;
+import com.vaadin.ui.Label;
+
+import java.io.Serializable;
+import java.util.LinkedHashSet;
+import java.util.Objects;
+
+/**
+ * Generic {@link HasValue} to use any type of component with Vaadin data binding.
+ * <p>
+ * Example:
+ * <pre>
+ * Label label = new Label();
+ * ReadOnlyHasValue&lt;String&gt; hasValue = new ReadOnlyHasValue&lt;&gt;(label::setCaption);
+ * binder.forField(hasValue).bind(SomeBean::getName);
+ * </pre>
+ *
+ * @param <V> the value type
+ * @since
+ */
+public class ReadOnlyHasValue<V> implements HasValue<V>, Serializable {
+    private V value;
+    private final SerializableConsumer<V> valueProcessor;
+    private final V emptyValue;
+    private LinkedHashSet<ValueChangeListener<V>> listenerList;
+
+    /**
+     * Creates new {@code ReadOnlyHasValue}
+     *
+     * @param valueProcessor the value valueProcessor, e.g. {@link Label#setValue}
+     * @param emptyValue the value to be used as empty, {@code null} by default
+     */
+    public ReadOnlyHasValue(SerializableConsumer<V> valueProcessor, V emptyValue) {
+        this.valueProcessor = valueProcessor;
+        this.emptyValue = emptyValue;
+    }
+
+    /**
+     * Creates new {@code ReadOnlyHasValue} with {@code null} as an empty value.
+     *
+     * @param valueProcessor the value valueProcessor, e.g. {@link Label#setValue}
+     */
+    public ReadOnlyHasValue(SerializableConsumer<V> valueProcessor) {
+        this(valueProcessor,null);
+    }
+
+    @Override
+    public void setValue(V value) {
+        V oldValue = this.value;
+        this.value = value;
+        valueProcessor.accept(value);
+        if (listenerList != null && ! Objects.equals(oldValue, value)) {
+            for (ValueChangeListener<V> valueChangeListener : listenerList) {
+                valueChangeListener.valueChange(
+                        new ValueChangeEvent<>(null, this, oldValue, false));
+            }
+        }
+    }
+
+    @Override
+    public V getValue() {
+        return value;
+    }
+
+    @Override
+    public Registration addValueChangeListener(
+            ValueChangeListener<V> listener) {
+        Objects.requireNonNull(listener, "Listener must not be null.");
+        if (listenerList == null) {
+            listenerList = new LinkedHashSet<>();
+        }
+        listenerList.add(listener);
+
+        return () -> listenerList.remove(listener);
+    }
+
+    @Override
+    public boolean isRequiredIndicatorVisible() {
+        return false;
+    }
+
+    @Override
+    public void setRequiredIndicatorVisible(boolean requiredIndicatorVisible) {
+        if (requiredIndicatorVisible) throw new IllegalArgumentException("Not Writable");
+    }
+
+    @Override
+    public void setReadOnly(boolean readOnly) {
+        if (!readOnly) throw new IllegalArgumentException("Not Writable");
+    }
+
+    @Override
+    public boolean isReadOnly() {
+        return true;
+    }
+
+    @Override
+    public V getEmptyValue() {
+        return emptyValue;
+    }
+}