Implemented multi Iterator class that combines multiple iterators as one.

test/zutil/struct/MultiIteratorTest.java

@@ -0,0 +1,76 @@
+/*
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2020 Ziver Koc
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+package zutil.struct;
+
+import org.junit.Test;
+
+import java.util.Arrays;
+import java.util.NoSuchElementException;
+
+import static org.junit.Assert.*;
+
+public class MultiIteratorTest {
+
+    @Test(expected = NoSuchElementException.class)
+    public void emptyTest() {
+        MultiIterator<String> it = new MultiIterator<>();
+        assertEquals(false, it.hasNext());
+        it.next(); // NoSuchElementException
+    }
+
+    @Test
+    public void oneIteratorTest() {
+        MultiIterator<String> it = new MultiIterator<>();
+        it.addIterator(Arrays.asList("value1", "value2").iterator());
+
+        assertEquals(true, it.hasNext());
+        assertEquals("value1", it.next());
+
+        assertEquals(true, it.hasNext());
+        assertEquals("value2", it.next());
+
+        assertEquals(false, it.hasNext());
+    }
+
+    @Test
+    public void multiIteratorTest() {
+        MultiIterator<String> it = new MultiIterator<>();
+        it.addIterator(Arrays.asList("value1", "value2").iterator());
+        it.addIterator(Arrays.asList("value3", "value4").iterator());
+        it.addIterator(Arrays.asList("value5", "value6").iterator());
+
+        assertEquals("value1", it.next());
+        assertEquals("value2", it.next());
+
+        assertEquals(true, it.hasNext());
+        assertEquals("value3", it.next());
+        assertEquals("value4", it.next());
+
+        assertEquals("value5", it.next());
+        assertEquals("value6", it.next());
+
+        assertEquals(false, it.hasNext());
+    }
+}