Added ObjectUtil class

src/zutil/ObjectUtil.java

@@ -0,0 +1,27 @@
+package zutil;
+
+import java.util.List;
+import java.util.Map;
+
+/**
+ * A utility class containing general object functions
+ */
+public class ObjectUtil {
+
+    /**
+     * @return true if obj is null or empty String, List, Map
+     */
+    public static boolean isEmpty(Object obj) {
+        if (obj == null)
+            return true;
+
+        if (obj instanceof Map)
+            return ((Map) obj).isEmpty();
+        else if (obj instanceof List)
+            return ((List) obj).isEmpty();
+        else if (obj instanceof CharSequence)
+            return ((CharSequence) obj).length() == 0;
+
+        return false; // We don't know the type of class, but it is not null
+    }
+}

test/zutil/ObjectUtilTest.java

@@ -0,0 +1,29 @@
+package zutil;
+
+import org.junit.Test;
+
+import java.util.*;
+
+import static org.junit.Assert.*;
+
+public class ObjectUtilTest {
+
+    @Test
+    public void isEmpty() {
+        assertTrue(ObjectUtil.isEmpty(null));
+        assertTrue(ObjectUtil.isEmpty(""));
+        assertTrue(ObjectUtil.isEmpty(new StringBuffer()));
+        assertTrue(ObjectUtil.isEmpty(new StringBuilder()));
+        assertTrue(ObjectUtil.isEmpty(new ArrayList<>()));
+        assertTrue(ObjectUtil.isEmpty(new LinkedList<>()));
+        assertTrue(ObjectUtil.isEmpty(new HashMap<>()));
+        assertTrue(ObjectUtil.isEmpty(new Hashtable<>()));
+
+
+        assertFalse(ObjectUtil.isEmpty(" "));
+        assertFalse(ObjectUtil.isEmpty("a"));
+        assertFalse(ObjectUtil.isEmpty(new StringBuilder("a")));
+        assertFalse(ObjectUtil.isEmpty(new StringBuffer("a")));
+        assertFalse(ObjectUtil.isEmpty(Arrays.asList(1, 2, 3)));
+    }
+}