add:

- CollectionUtils class and its unit test.

SVN: 1622

common/source/java/ch/systemsx/cisd/common/utilities/CollectionUtils.java

+/*
+ * Copyright 2007 ETH Zuerich, CISD
+ *
+ * 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 ch.systemsx.cisd.common.utilities;
+
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.Iterator;
+
+/**
+ * Some convenience methods/utilities around {@link Collection}.
+ * 
+ * @author Christian Ribeaud
+ */
+public final class CollectionUtils
+{
+
+    public final static String DEFAULT_COLLECTION_START = "[";
+
+    public final static String DEFAULT_COLLECTION_END = "]";
+
+    public final static String DEFAULT_COLLECTION_SEPARATOR = ", ";
+
+    private static String collectionStart = DEFAULT_COLLECTION_START;
+
+    private static String collectionEnd = DEFAULT_COLLECTION_END;
+
+    private static String collectionSeparator = DEFAULT_COLLECTION_SEPARATOR;
+
+    private CollectionUtils()
+    {
+        // Can not be instantiated
+    }
+
+    public static final void setCollectionEnd(String collectionEnd)
+    {
+        CollectionUtils.collectionEnd = collectionEnd;
+    }
+
+    public static final void setCollectionSeparator(String collectionSeparator)
+    {
+        CollectionUtils.collectionSeparator = collectionSeparator;
+    }
+
+    public static final void setCollectionStart(String collectionStart)
+    {
+        CollectionUtils.collectionStart = collectionStart;
+    }
+
+    public static final String getCollectionEnd()
+    {
+        return collectionEnd;
+    }
+
+    public static final String getCollectionSeparator()
+    {
+        return collectionSeparator;
+    }
+
+    public static final String getCollectionStart()
+    {
+        return collectionStart;
+    }
+
+    /**
+     * Abbreviates a given array of <code>Object</code> using ellipses.
+     * <p>
+     * By default it shows the number of items left.
+     * </p>
+     * 
+     * @param maxLength the maximum number of items that should be shown. If <code>-1</code> then all items will be
+     *            displayed.
+     */
+    public final static String abbreviate(Object[] objects, int maxLength)
+    {
+        return abbreviate(objects, maxLength, true);
+    }
+
+    /**
+     * Abbreviates a given <code>Collection</code> using ellipses.
+     * <p>
+     * By default it shows the number of items left.
+     * </p>
+     * 
+     * @param maxLength the maximum number of items that should be shown. If <code>-1</code> then all items will be
+     *            displayed.
+     */
+    public final static String abbreviate(Collection<?> collection, int maxLength)
+    {
+        return abbreviate(collection, maxLength, true);
+    }
+
+    /**
+     * Abbreviates a given array of <code>Object</code> using ellipses.
+     * 
+     * <pre>
+     * CollectionUtils.abbreviate(new String[] { "1", "2", "3", "4", "5" }, 3, false) = "[1, 2, 3, ...]"
+     * CollectionUtils.abbreviate(new String[] { "1", "2", "3", "4", "5" }, 3, true) = "[1, 2, 3, ... (2 left)]"
+     * </pre>
+     * 
+     * @param maxLength the maximum number of items that should be shown. If <code>-1</code> then all items will be
+     *            displayed.
+     * @param showLeft whether the number of items left should be displayed at the end of the output. This is only
+     *            relevant if you limit the number of items displayed.
+     */
+    public final static String abbreviate(Object[] objects, int maxLength, boolean showLeft)
+    {
+        return abbreviate(Arrays.asList(objects), maxLength, showLeft);
+    }
+
+    /**
+     * Abbreviates a given <code>Collection</code> using ellipses.
+     * 
+     * @param maxLength the maximum number of items that should be shown. If <code>-1</code> then all items will be
+     *            displayed.
+     * @param showLeft whether the number of items left should be displayed at the end of the output. This is only
+     *            relevant if you limit the number of items displayed.
+     */
+    public final static String abbreviate(Collection<?> collection, int maxLength, boolean showLeft)
+    {
+        assert collection != null;
+        StringBuilder builder = new StringBuilder(collectionStart);
+        Iterator<?> iterator = collection.iterator();
+        for (int i = 0; iterator.hasNext() && (i < maxLength || maxLength < 0); i++)
+        {
+            if (i > 0)
+            {
+                builder.append(collectionSeparator);
+            }
+            builder.append(String.valueOf(iterator.next()));
+        }
+        int size = collection.size();
+        if (maxLength > 0 && maxLength < size)
+        {
+            builder.append(collectionSeparator);
+            builder.append("...");
+            if (showLeft)
+            {
+                builder.append(" (").append(size - maxLength).append(" left)");
+            }
+        }
+        builder.append(collectionEnd);
+        return builder.toString();
+    }
+}
\ No newline at end of file

common/sourceTest/java/ch/systemsx/cisd/common/utilities/CollectionUtilsTest.java

+/*
+ * Copyright 2007 ETH Zuerich, CISD
+ *
+ * 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 ch.systemsx.cisd.common.utilities;
+
+import static org.testng.AssertJUnit.*;
+
+import java.util.Collection;
+
+import org.apache.commons.lang.StringUtils;
+import org.testng.annotations.Test;
+
+/**
+ * Test cases for the {@link CollectionUtils} class.
+ * 
+ * @author Christian Ribeaud
+ */
+public final class CollectionUtilsTest
+{
+
+    @Test
+    public final void testAbbreviateWithArray()
+    {
+        try
+        {
+            CollectionUtils.abbreviate((Collection<?>) null, 0, false);
+            fail("Given list can not be null.");
+        } catch (AssertionError e)
+        {
+            // Nothing to do here
+        }
+        String[] s = StringUtilities.getStrings(5);
+        String string =
+                CollectionUtils.getCollectionStart() + StringUtils.join(s, CollectionUtils.getCollectionSeparator())
+                        + CollectionUtils.getCollectionEnd();
+        assertEquals(string, CollectionUtils.abbreviate(s, -1, false));
+        assertEquals(string, CollectionUtils.abbreviate(s, -10, false));
+        assertEquals(string, CollectionUtils.abbreviate(s, 5, false));
+        assertEquals(string, CollectionUtils.abbreviate(s, 10, false));
+        // With ellipses
+        s = new String[]
+            { "1", "2", "3", "4", "5" };
+        assertEquals("[1, 2, 3, ...]", CollectionUtils.abbreviate(s, 3, false));
+        assertEquals("[1, ...]", CollectionUtils.abbreviate(s, 1, false));
+        assertEquals("[]", CollectionUtils.abbreviate(s, 0, false));
+        // With show left
+        assertEquals("[]", CollectionUtils.abbreviate(s, 0));
+        assertEquals("[1, ... (4 left)]", CollectionUtils.abbreviate(s, 1));
+        assertEquals("[1, 2, ... (3 left)]", CollectionUtils.abbreviate(s, 2));
+        assertEquals(CollectionUtils.abbreviate(s, 10, false), CollectionUtils.abbreviate(s, 10));
+    }
+}