Merge pull request #42 from CheungChanDevCoder/master

将ensureCapacity设为public方法 忽略bin文件夹

group05/1377699408/作业/20170226/.gitignore

@@ -0,0 +1,4 @@
+/bin
+/.settings
+.classpath
+.project

group05/1377699408/作业/20170226/src/list/ArrayList.java

@@ -0,0 +1,56 @@
+package list;
+
+import java.util.Arrays;
+
+public class ArrayList<E> {
+	private transient static final int INITIAL_SIZE = 10;
+	private transient int arrayLength;
+	private transient int size;
+	private transient E[] array;
+	public ArrayList(){
+		array = (E[]) new Object[INITIAL_SIZE];
+		arrayLength = INITIAL_SIZE;
+	}
+	public ArrayList(int size){
+		if(size<=0){
+			throw new IllegalArgumentException("参数不可以小于0");
+		}
+		array = (E[])new Object[size];
+		arrayLength = array.length;
+		ensureCapacity(size);
+		this.size = size;
+	}
+	public int size(){
+		return size;
+	}
+	public void add(E e){
+		ensureCapacity(size+1);
+		array[size] = e;
+		size++;
+	}
+	public E get(int index){
+		if(index<0 || index > size){
+			throw new IllegalArgumentException("索引越界");
+		}
+		return array[index];
+
+	}
+	public E set(int index, E e){
+		if(index<0 || index>size){
+			throw new IllegalArgumentException("索引越界");
+		}
+		E result = array[index];
+		array[index] = e;
+		return result;
+	}
+	public void ensureCapacity(int size){
+		E[] oldArray = array;
+		int oldSize = arrayLength;
+		while(size>arrayLength){
+			arrayLength = arrayLength + (arrayLength >> 1);
+		}
+		if(oldSize!=arrayLength){
+			array = Arrays.copyOf(oldArray, arrayLength);
+		}
+	}
+}