java常用集合效率测试

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测试了下jave常见集合添加与删除效率，包括ArrayList、LinkedList、HashMap、TreeSet、LinkedHashMap

java具体集合有以下：

集合类型描述
ArrayList 一种可以动态增长和缩减的索引序列
LinkedList 一种可以在任何位置进行高效的插入和删除操作的有序序列
ArrayDeque 一种用循环数组实现的双端队列
HashSet 一种没有重复元素的无序集合
TreeSet 一种有序集
EnumSet 一种包含枚举类型值的集
LinkedHashSet 一种可以记住元素插入次序的集
PriorityQueue 一种允许高效删除最小元素的集
HashMap 一种存储键/值关联的数据结构
TreeMap 一种键值有序排列的映射表
EnumMaP 一种键值属于枚举类型的映射表
LinkedHashMap 一种可以记住键/值添加次序的映射表
WeakHashMap 一种其值无用武之地后可以被垃圾回收器回收的映射表
IdentityHashMap 一种用 == 而不是用equals比较键值的映射表

1.添加效率测试：

测试代码如下：

        int num = 1000000;        ArrayList<StudyRecordBean> als = new ArrayList<>();        long l1 = System.currentTimeMillis();        for (int i = 0; i < num; i++) {            StudyRecordBean s1 = new StudyRecordBean();            als.add(s1);        }        long l2 = System.currentTimeMillis();        System.out.println("ArrayList:"+(l2 - l1) + "");        LinkedList<StudyRecordBean> lls = new LinkedList<>();        long l3 = System.currentTimeMillis();        for (int i = 0; i < num; i++) {            StudyRecordBean s1 = new StudyRecordBean();            lls.add(s1);        }        long l4 = System.currentTimeMillis();        System.out.println("LinkedList:"+(l4 - l3) + "");        long l5 = System.currentTimeMillis();        HashMap<Integer, StudyRecordBean> hsm = new HashMap<>();        for (int i = 0; i < num; i++) {            hsm.put(i, new StudyRecordBean());        }        long l6 = System.currentTimeMillis();        System.out.println("HashMap:"+(l6 - l5) + "");        TreeSet<StudyRecordBean> trs = new TreeSet<>();        long l7 = System.currentTimeMillis();        for (int i = 0; i < num; i++) {                 trs.add(new StudyRecordBean());        }        long l8 = System.currentTimeMillis();        System.out.println("TreeSet:"+(l8 - l7) + "");        TreeMap<Integer,StudyRecordBean> trm = new TreeMap<>();        long l9 = System.currentTimeMillis();        for (int i = 0; i < num; i++) {                 trm.put(i, new StudyRecordBean());        }        long l10 = System.currentTimeMillis();        System.out.println("TreeMap:"+(l10 - l9) + "");        LinkedHashMap<Integer, StudyRecordBean> lhsm = new LinkedHashMap();        long l11 = System.currentTimeMillis();        for (int i = 0; i < num; i++) {                 lhsm.put(i, new StudyRecordBean());        }        long l12= System.currentTimeMillis();        System.out.println("LinkedHashMap:"+(l12 - l11) + "");

num=一万时，输出如下：

ArrayList:4
LinkedList:3
HashMap:8
TreeSet:6
TreeMap:18
LinkedHashMap:6

num=十万时，输出如下：

ArrayList:19
LinkedList:6
HashMap:28
TreeSet:17
TreeMap:90
LinkedHashMap:28

num=一百万时，输出如下：

ArrayList:59
LinkedList:64
HashMap:331
TreeSet:111
TreeMap:356
LinkedHashMap:153

num=一千万时，输出如下：

ArrayList:4770
LinkedList:2761
HashMap:6334
TreeSet:1435
TreeMap:6888
LinkedHashMap:12199

对于超多数据时，TreeSet添加效率最高，其次：LinkedList>ArrayList>其他。

对于LinkedList、ArrayList，如果每次添加数据是从中间插入的话：

int num = 100000;        ArrayList<StudyRecordBean> als = new ArrayList<>();        long l1 = System.currentTimeMillis();        for (int i = 0; i < num; i++) {            StudyRecordBean s1 = new StudyRecordBean();            als.add(als.size()/2,s1);        }        long l2 = System.currentTimeMillis();        System.out.println("ArrayList:"+(l2 - l1) + "");        LinkedList<StudyRecordBean> lls = new LinkedList<>();        long l3 = System.currentTimeMillis();        for (int i = 0; i < num; i++) {            StudyRecordBean s1 = new StudyRecordBean();            lls.add(lls.size()/2,s1);        }        long l4 = System.currentTimeMillis();        System.out.println("LinkedList:"+(l4 - l3) + "");

插入1万条数据，每次都是从中间插入，输出：

ArrayList:10
LinkedList:82
HashMap:10
TreeSet:0
TreeMap:11
LinkedHashMap:3

插入三万条数据，每次都是从中间插入，输出：

ArrayList:35
LinkedList:671
HashMap:12
TreeSet:43
TreeMap:17
LinkedHashMap:7

插入十万条数据，每次都是从中间插入，输出：

ArrayList:332
LinkedList:16666
HashMap:27
TreeSet:5
TreeMap:56
LinkedHashMap:27

对于从中间某位置插入，ArrayList效率远高于LinkedList

添加数据小结：

对于有序列表：
如果添加到尾部，LinkedList效率比较高；如果插入都中间某位置ArrayList效率会比较高。
对于无序集合：
TreeSet>HashMap>LinkedHashMap

2读取效率测试

测试包括：ArrayList、LinkedList、HashMap、LinkedHashMap

测试代码如下：

    public static int num = 10000000;    public static ArrayList<StudyRecordBean> als;    public static LinkedList<StudyRecordBean> lls;    public static HashMap<Integer, StudyRecordBean> hsm;    public static TreeSet<StudyRecordBean> trs;    public static TreeMap<Integer, StudyRecordBean> trm;    public static LinkedHashMap<Integer, StudyRecordBean> lhsm;public static void main(String[] args) {        Add();        testRead();    }    private static void testRead() {        long l1 = System.currentTimeMillis();        for (int i = 0; i < num; i++) {            als.get(i);        }        long l2 = System.currentTimeMillis();        System.out.println("ArrayList:" + (l2 - l1) + "");        long l3 = System.currentTimeMillis();        for (int i = 0; i < num; i++) {            lls.get(i);        }        long l4 = System.currentTimeMillis();        System.out.println("LinkedList:" + (l4 - l3) + "");        long l5 = System.currentTimeMillis();        for (int i = 0; i < num; i++) {            hsm.get(i);        }        long l6 = System.currentTimeMillis();        System.out.println("HashMap:" + (l6 - l5) + "");        long l9 = System.currentTimeMillis();        for (int i = 0; i < num; i++) {            trm.get(i);        }        long l10 = System.currentTimeMillis();        System.out.println("TreeMap:" + (l10 - l9) + "");        long l11 = System.currentTimeMillis();        for (int i = 0; i < num; i++) {            lhsm.get(i);        }        long l12 = System.currentTimeMillis();        System.out.println("LinkedHashMap:" + (l12 - l11) + "");    }    private static void Add() {        als = new ArrayList<>();        for (int i = 0; i < num; i++) {            StudyRecordBean s1 = new StudyRecordBean();            als.add(als.size(), s1);        }        lls = new LinkedList<>();        for (int i = 0; i < num; i++) {            StudyRecordBean s1 = new StudyRecordBean();            lls.add(lls.size(), s1);        }        hsm = new HashMap<>();        for (int i = 0; i < num; i++) {            hsm.put(i, new StudyRecordBean());        }        trs = new TreeSet<>();        for (int i = 0; i < num; i++) {            trs.add(new StudyRecordBean());        }        trm = new TreeMap<>();        for (int i = 0; i < num; i++) {            trm.put(i, new StudyRecordBean());        }        lhsm = new LinkedHashMap();        for (int i = 0; i < num; i++) {            lhsm.put(i, new StudyRecordBean());        }    }