Added CircularBuffer class

src/zutil/struct/CircularBuffer.java

@@ -0,0 +1,108 @@
+/*
+ * Copyright (c) 2015 ezivkoc
+ *
+ * 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 sun.reflect.generics.reflectiveObjects.NotImplementedException;
+
+import java.util.Iterator;
+import java.util.NoSuchElementException;
+
+/**
+ * This class is a first in first out circular buffer with a fixed size.
+ * If the size is exceed then the oldest item will be removed.
+ * Created by Ziver on 2015-09-22.
+ */
+public class CircularBuffer<T> implements Iterable<T>{
+
+    private Object[] buffer;
+    private int buffSize;
+    private int buffPos;
+    private long addCount;
+
+    /**
+     * Initiates the buffer with a maximum size of maxSize.
+     */
+    public CircularBuffer(int maxSize){
+        buffer = new Object[maxSize];
+        buffSize = 0;
+        buffPos  = 0;
+    }
+
+    public void add(T obj){
+        if(buffPos+1 >= buffer.length)
+            buffPos = 0;
+        else
+            ++buffPos;
+        if(buffSize < buffer.length)
+            ++buffSize;
+        buffer[buffPos] = obj;
+        ++addCount;
+    }
+
+    public T get(int index) {
+        if(index >= buffSize)
+            throw new IndexOutOfBoundsException("Index "+ index +" is larger than actual buffer size "+ buffSize);
+        int buffIndex = buffPos - index;
+        if(buffIndex < 0)
+            buffIndex = buffer.length - Math.abs(buffIndex);
+        return (T)buffer[buffIndex];
+    }
+
+    public int size() {
+        return buffSize;
+    }
+
+    /**
+     * @return the total amount of insertions into the buffer, this value only increments and will never decrease.
+     */
+    public long getInsertionCount() {
+        return addCount;
+    }
+
+    @Override
+    public Iterator<T> iterator() {
+        return new CircularBufferIterator();
+    }
+
+
+    protected class CircularBufferIterator implements Iterator<T> {
+        private int iteratorPos = 0;
+
+        @Override
+        public boolean hasNext() {
+            return iteratorPos < buffSize;
+        }
+
+        @Override
+        public T next() {
+            if(iteratorPos >= buffSize)
+                throw new NoSuchElementException();
+            return get(iteratorPos++);
+        }
+
+        @Override
+        public void remove() {
+            throw new NotImplementedException();
+        }
+    }
+}

src/zutil/test/CircularBufferTest.java

@@ -0,0 +1,116 @@
+/*
+ * Copyright (c) 2015 ezivkoc
+ *
+ * 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.test;
+
+import org.junit.Test;
+import zutil.struct.CircularBuffer;
+
+import java.util.Iterator;
+import java.util.NoSuchElementException;
+
+import static org.junit.Assert.*;
+
+/**
+ * Created by Ziver on 2015-09-22.
+ */
+public class CircularBufferTest {
+
+    @Test
+    public void addToEmpty() {
+        CircularBuffer<Integer> buff = new CircularBuffer<Integer>(0);
+        try {
+            buff.add(10);
+            fail("IndexOutOfBoundsException was not thrown");
+        } catch (IndexOutOfBoundsException e) {}
+    }
+
+    @Test
+    public void addOneElement() {
+        CircularBuffer<Integer> buff = new CircularBuffer<Integer>(1);
+        assertEquals(0, buff.size());
+        buff.add(10);
+        assertEquals(1, buff.size());
+        assertEquals((Integer) 10, buff.get(0));
+    }
+
+    @Test
+    public void addThreeElements() {
+        CircularBuffer<Integer> buff = new CircularBuffer<Integer>(10);
+        buff.add(10);
+        buff.add(11);
+        buff.add(12);
+        assertEquals(3, buff.size());
+        assertEquals((Integer) 12, buff.get(0));
+        assertEquals((Integer) 11, buff.get(1));
+        assertEquals((Integer) 10, buff.get(2));
+    }
+
+    @Test
+    public void addOutOfRange() {
+        CircularBuffer<Integer> buff = new CircularBuffer<Integer>(2);
+        buff.add(10);
+        buff.add(11);
+        buff.add(12);
+        assertEquals(2, buff.size());
+        assertEquals((Integer) 12, buff.get(0));
+        assertEquals((Integer) 11, buff.get(1));
+        try {
+            buff.get(2);
+            fail("IndexOutOfBoundsException was not thrown");
+        } catch (IndexOutOfBoundsException e) {}
+    }
+
+    @Test
+    public void iteratorEmpty() {
+        CircularBuffer<Integer> buff = new CircularBuffer<Integer>(10);
+        Iterator<Integer> it = buff.iterator();
+
+        assert (!it.hasNext());
+        try {
+            it.next();
+            fail("NoSuchElementException was not thrown");
+        } catch (NoSuchElementException e) {}
+    }
+
+    @Test
+    public void iteratorThreeElements() {
+        CircularBuffer<Integer> buff = new CircularBuffer<Integer>(10);
+        buff.add(10);
+        buff.add(11);
+        buff.add(12);
+
+        Iterator<Integer> it = buff.iterator();
+        assert (it.hasNext());
+        assertEquals((Integer) 12, it.next());
+        assert (it.hasNext());
+        assertEquals((Integer) 11, it.next());
+        assert (it.hasNext());
+        assertEquals((Integer) 10, it.next());
+        assert (!it.hasNext());
+
+        try {
+            it.next();
+            fail("NoSuchElementException was not thrown");
+        } catch (NoSuchElementException e) {}
+    }
+}