添加SimpleArrayList的get方法

byhieg · byhieg · commit 4c3bb7aaffee · 2017-02-07T23:55:54.000+08:00
diff --git a/src/main/java/cn/byhieg/collectiontutorial/listtutorial/MyArrayList.java b/src/main/java/cn/byhieg/collectiontutorial/listtutorial/MyArrayList.java
diff --git a/src/main/java/cn/byhieg/collectiontutorial/listtutorial/SimpleArrayList.java b/src/main/java/cn/byhieg/collectiontutorial/listtutorial/SimpleArrayList.java
@@ -0,0 +1,76 @@
+package cn.byhieg.collectiontutorial.listtutorial;
+
+import java.util.Arrays;
+
+/**
+ * Created by byhieg on 17/2/7.
+ * Mail to byhieg@gmail.com
+ */
+public class SimpleArrayList<E> {
+
+
+    private final static int DEFAULT_CAPACITY = 10;
+    private int size = 0;
+
+    private Object [] elementData;
+
+    public SimpleArrayList(){
+        this(DEFAULT_CAPACITY);
+    }
+
+
+    public SimpleArrayList(int size){
+        if (size < 0){
+            throw new IllegalArgumentException("&#40664;&#35748;&#30340;&#22823;&#23567;" + size);
+        }else{
+            elementData = new Object[size];
+        }
+    }
+
+
+    public void add(E e){
+        isCapacityEnough(size + 1);
+        elementData[size++] = e;
+    }
+
+    public void add(int index, E e) {
+        checkRangeForAdd(index);
+        isCapacityEnough(size + 1);
+        System.arraycopy(elementData,index,elementData,index + 1,size - index);
+        elementData[index] = e;
+        size++;
+    }
+
+    private void isCapacityEnough(int size){
+        if (size > DEFAULT_CAPACITY){
+            explicitCapacity(size);
+        }
+        if (size < 0){
+            throw new OutOfMemoryError();
+        }
+    }
+    private final static int MAX_ARRAY_LENGTH = Integer.MAX_VALUE - 8;
+
+    private void explicitCapacity(int capacity){
+        int newLength = elementData.length * 2;
+        if (newLength - capacity < 0){
+            newLength = capacity;
+        }
+        if (newLength > (MAX_ARRAY_LENGTH)){
+            newLength = (capacity > MAX_ARRAY_LENGTH ? Integer.MAX_VALUE : MAX_ARRAY_LENGTH);
+        }
+        elementData = Arrays.copyOf(elementData, newLength);
+    }
+
+    private void checkRangeForAdd(int index){
+        if (index < 0 || index > size){
+            throw new IndexOutOfBoundsException("&#25351;&#23450;&#30340;index&#36229;&#36807;&#30028;&#38480;");
+        }
+    }
+
+    public E get(int index){
+
+    }
+
+    
+}
diff --git a/src/test/java/cn/byhieg/collectiontutorialtest/SimpleArrayListTest.java b/src/test/java/cn/byhieg/collectiontutorialtest/SimpleArrayListTest.java
@@ -0,0 +1,24 @@
+package cn.byhieg.collectiontutorialtest;
+
+import cn.byhieg.collectiontutorial.listtutorial.SimpleArrayList;
+import junit.framework.TestCase;
+
+import java.util.ArrayList;
+
+/**
+ * Created by byhieg on 17/2/7.
+ * Mail to byhieg@gmail.com
+ */
+public class SimpleArrayListTest extends TestCase {
+    public void testAdd() throws Exception {
+        SimpleArrayList<Integer> list = new SimpleArrayList<>();
+        for (int i = 0 ; i < 20 ; i++){
+            list.add(i);
+        }
+
+        list.add(5,15);
+
+        System.out.println("aaa");
+    }
+
+}
