Merge pull request #1 from eloiseSJTU/master

Assignment 2 spec update

.gitignore

@@ -1,5 +1,4 @@
 *.class
-
 # Mobile Tools for Java (J2ME)
 .mtj.tmp/
 
@@ -8,9 +7,25 @@
 *.war
 *.ear
 
+*.iml
+*.idea
+
+
 # virtual machine crash logs, see http://www.java.com/en/download/help/error_hotspot.xml
 hs_err_pid*
 
 #ide config
 .metadata
 .recommenders
+
+
+#macOS
+.DS_Store
+
+.idea/
+*.iml
+rebel.*
+.rebel.*
+
+target
+

group02/106614649/106614649Learnin/src/com/github/Ven13/coding2017/basic/ArrayList.java

@@ -0,0 +1,97 @@
+package com.github.Ven13.coding2017.basic;
+
+public class ArrayList implements List {
+
+	//返回集合大小
+	private int size = 0;
+
+	//先给定一个长度为10的数组
+	Object[] elementData = new Object[100];
+
+	@Override
+	//动态添加元素
+	public void add(Object o) {
+		//先判断数组是否已满
+		if(size == elementData.length) {
+			Object[] newObjects = new Object[elementData.length * 2];
+			System.arraycopy(elementData, 0, newObjects, 0, elementData.length);
+			elementData = newObjects;
+		}
+
+		//为新添加的元素指定下标
+		elementData[size] = o;
+		size++;
+	}
+
+	@Override
+	public void add(int index, Object o) {
+		//先判断数组是否已满
+		if(size == elementData.length) {
+			Object[] newObjects = elementData;
+			this.elementData = new Object[elementData.length * 2];
+			for(int j = 0; j < newObjects.length; j++) {
+				this.elementData[j] = newObjects[j];
+			}
+		}
+
+		for(int i = size - 1; i >= index; i--) {
+			elementData[i+1] = elementData[i];
+		}
+
+		elementData[index] = o;
+		size++;
+	}
+
+	@Override
+	public Object get(int index) {
+		return elementData[index];
+	}
+
+	@Override
+	public Object remove(int index) {
+		if (index > size) {
+			return null;
+		};
+
+		int moveSize = size - index - 1;
+
+		if (moveSize > 0) {
+			System.arraycopy(elementData, index + 1, elementData, index, size - index - 1);
+		}
+		elementData[--size] = null;
+
+		//for(int i = index; i < elementData.length; i++) {
+		//	elementData[i] = elementData[i+1];
+		//}
+
+		return elementData;
+	}
+
+	@Override
+	public int size() {
+		return size;
+	}
+
+	public Iterator iterator(){
+		return new ArrayListIterator();
+	}
+
+	private class ArrayListIterator implements Iterator {
+
+		private int currentIndex = 0;
+
+		@Override
+		public boolean hasNext() {
+			if(currentIndex >= size) return false;
+			else return true;
+		}
+
+		@Override
+		public Object next() {
+			Object o = elementData[currentIndex];
+		    currentIndex ++;
+		    return o;
+		}
+	}
+
+}