- [ArrayList](#arraylist)
- [ArrayList](#arraylist)
- [ArrayList](#arraylist)
    - [System.arraycopy\(\)Arrays.copyOf\(\)](#systemarraycopyarrayscopyof)
        - [](#)
    - [ArrayList](#arraylist)
    - [](#)
- [ArrayListDemo](#arraylistdemo)


### ArrayList
ArrayList  Java `ensureCapacity` ArrayList 
    
    **AbstractList** **List**, **RandomAccess**, **Cloneable**, **java.io.Serializable** 
    
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  ArrayList AbstractListList

ArrayList **RandomAccess ** RandomAccess  List **** ArrayList 

ArrayList **Cloneable ** clone()****

ArrayList **java.io.Serializable **ArrayList********

 Vector **ArrayList ** ArrayList Vector   CopyOnWriteArrayList
### ArrayList

```java
package java.util;

import java.util.function.Consumer;
import java.util.function.Predicate;
import java.util.function.UnaryOperator;


public class ArrayList extends AbstractList
        implements List, RandomAccess, Cloneable, java.io.Serializable
{
    private static final long serialVersionUID = 8683452581122892189L;

    /**
     * 
     */
    private static final int DEFAULT_CAPACITY = 10;

    /**
     * 
     */
    private static final Object[] EMPTY_ELEMENTDATA = {};

     //
      //EMPTY_ELEMENTDATA
    private static final Object[] DEFAULTCAPACITY_EMPTY_ELEMENTDATA = {};

    /**
     * ArrayList
     */
    transient Object[] elementData; // non-private to simplify nested class access

    /**
     * ArrayList 
     */
    private int size;

    /**
     * 
     */
    public ArrayList(int initialCapacity) {
        if (initialCapacity > 0) {
            //initialCapacity
            this.elementData = new Object[initialCapacity];
        } else if (initialCapacity == 0) {
            //
            this.elementData = EMPTY_ELEMENTDATA;
        } else {
            throw new IllegalArgumentException("Illegal Capacity: "+
                                               initialCapacity);
        }
    }

    /**
     *DEFAULTCAPACITY_EMPTY_ELEMENTDATA 0.10 10
     */
    public ArrayList() {
        this.elementData = DEFAULTCAPACITY_EMPTY_ELEMENTDATA;
    }

    /**
     * 
     */
    public ArrayList(Collection