java免费源码大全（java的免费架构大全）

1 Java集合概览

2 List接口下集合源码分析

2.1 ArrayList

（1）集合体系

（2）基本使用

//实例化
ArrayList<Integer> list = new ArrayList<>(5);
//添加元素
list.add(1);
list.add(2);
//遍历元素
for (Integer i : list) {
System.out.print(i);
}
for (int i = 0; i < list.size(); i++) {
System.out.print(list.get(i));
}
//删除元素
System.out.println(list.remove(0));

（3）源码剖析

• 线程安全问题：线程不安全
• public boolean add(E e) {
  ensureCapacityInternal(size + 1); // Increments modCount!!elementData[size++] = e;return true;}
• 理由：没有任何线程同步机制和分段锁等保护线程安全的措施
• 扩容机制：当元素添加满时将数组大小扩大1.5倍
• //主要是调用grow方法进行扩容
  private void grow(int minCapacity) {// overflow-conscious codeint oldCapacity = elementData.length;int newCapacity = oldCapacity + (oldCapacity >> 1);if (newCapacity - minCapacity < 0)newCapacity = minCapacity;if (newCapacity - MAX_ARRAY_SIZE > 0)newCapacity = hugeCapacity(minCapacity);// minCapacity is usually close to size, so this is a win:elementData = Arrays.copyOf(elementData, newCapacity);}
• 元素是否可以为null：可以为null
• public boolean add(E e) {
  ensureCapacityInternal(size + 1); // Increments modCount!!elementData[size++] = e;return true;}
• 添加元素时并没有代码要求元素不能为null

2.2 LinkedList

（1）集合体系

（2）基本使用

//实例化
LinkedList linkedList = new LinkedList();
//添加元素
linkedList.add(23);
linkedList.add(44);
linkedList.add(12);
//删除元素，删除的是第一个结点
linkedList.remove();
//修改某个结点对象
linkedList.set(1, 999);
//获取链表的第二个对象
Object o = linkedList.get(1);
//遍历
Iterator iterator = linkedList.iterator();
while (iterator.hasNext()) {
Object next = iterator.next();
System.out.print(next);
}
for (Object o1 : linkedList) {
System.out.print(o1);
}
for (int i = 0; i < linkedList.size(); i++) {
System.out.print(linkedList.get(i));
}

（3）源码剖析

• 是否需要扩容：不需要扩容，添加元素时直接放在队列的尾部，由上一个元素的next指针指该元素
• public boolean add(E e) {
  linkLast(e);return true;}void linkLast(E e) {final Node<E> l = last;final Node<E> newNode = new Node<>(l, e, null);last = newNode;if (l == null)first = newNode;elsel.next = newNode;size++;modCount++;}
• 删除元素过程：将被删除元素的上一个节点的next指针指向被删除元素的下一个节点
• public E remove(int index) {
  checkElementIndex(index);return unlink(node(index));}E unlink(Node<E> x) {// assert x != null;final E element = x.item;final Node<E> next = x.next;final Node<E> prev = x.prev;if (prev == null) {first = next;} else {prev.next = next;x.prev = null;}if (next == null) {last = prev;} else {next.prev = prev;x.next = null;}x.item = null;size--;modCount++;return element;}

2.3 Vector

（1）集合体系

（2）基本使用

//实例化
Vector vector = new Vector(18);
//添加元素
vector.add(100);

（3）源码剖析

• 是否线程安全：线程安全，具有互斥锁synchronized
• public synchronized boolean add(E e) {
  modCount++;ensureCapacityHelper(elementCount + 1);elementData[elementCount++] = e;return true;}
• 扩容机制：当元素添加满时默认将数组大小扩大2倍，可以实例化时指定扩容的大小capacityIncrement
• private void grow(int minCapacity) {
  // overflow-conscious codeint oldCapacity = elementData.length;int newCapacity = oldCapacity + ((capacityIncrement > 0) ?capacityIncrement : oldCapacity);if (newCapacity - minCapacity < 0)newCapacity = minCapacity;if (newCapacity - MAX_ARRAY_SIZE > 0)newCapacity = hugeCapacity(minCapacity);elementData = Arrays.copyOf(elementData, newCapacity);}

3 Set接口下集合源码分析

3.1 HashSet

（1）集合体系

（2）基本使用

HashSet hashSet = new HashSet();
hashSet.add(null);
hashSet.add(null);
hashSet.add("2");
System.out.println("hashSet=" + hashSet);
hashSet.forEach(s -> System.out.println(s));
hashSet.remove(null);
System.out.println(hashSet.contains("2"));
System.out.println(hashSet.contains(null));

（3）源码剖析

• 底层：HashMap
• public HashSet() {
  map = new HashMap<>();}
• add方法：将HashMap的减存放元素，将HashMap的值放入空对象PRESENT，然后直接调用HashMap的add方法
• // Dummy value to associate with an Object in the backing Map
  private static final Object PRESENT = new Object();public boolean add(E e) {return map.put(e, PRESENT)==null;}
• 元素是否可以为null：可以

3.2 TreeSet

（1）集合体系

（2）基本使用

TreeSet treeSet = new TreeSet(new Comparator() {
//排序规则
@Override
public int compare(Object o1, Object o2) {
return ((String) o1).compareTo((String) o2);
}
});
treeSet.add("zs");
treeSet.add("ls");
treeSet.add("ww");
treeSet.add("zl");

（3）源码剖析

• 自定义元素排序规则：
• TreeSet treeSet = new TreeSet(new Comparator() {
  //排序规则 o1和o2代表先后元素的比较规则 (String) o1).compareTo((String) o2表示比较字符串的阿斯卡码 相同时不放入@Overridepublic int compare(Object o1, Object o2) {return ((String) o1).compareTo((String) o2);}});
• add方法：底层调用了TreeMap的put方法 m.put(e, PRESENT)
• public V put(K key, V value) {
  Entry<K,V> t = root;if (t == null) {compare(key, key); // type (and possibly null) checkroot = new Entry<>(key, value, null);size = 1;modCount++;return null;}int cmp;Entry<K,V> parent;// split comparator and comparable pathsComparator<? super K> cpr = comparator;if (cpr != null) {do {parent = t;cmp = cpr.compare(key, t.key);if (cmp < 0)t = t.left;else if (cmp > 0)t = t.right;elsereturn t.setValue(value);} while (t != null);}else {if (key == null)throw new NullPointerException();@SuppressWarnings("unchecked")Comparable<? super K> k = (Comparable<? super K>) key;do {parent = t;cmp = k.compareTo(t.key);if (cmp < 0)t = t.left;else if (cmp > 0)t = t.right;elsereturn t.setValue(value);} while (t != null);}Entry<K,V> e = new Entry<>(key, value, parent);if (cmp < 0)parent.left = e;elseparent.right = e;fixAfterInsertion(e);size++;modCount++;return null;}

3.3 LinkedHashSet

（1）集合体系

（2）基本使用

LinkedHashSet linkedHashSet = new LinkedHashSet();
linkedHashSet.add(1);
linkedHashSet.add(2);
linkedHashSet.add(new Student(1));
linkedHashSet.add(new Student(1));//只显示一个Student(1)

（3）源码剖析

略

4 Map接口下集合源码分析

4.1 HashMap

（1）集合体系

（2）基本使用

//实例化
HashMap<String, Object> map = new HashMap<>();
//放入元素
map.put("1", "zs");
map.put("2", "ls");
map.put("3", "ww");
//获取元素
Object o = map.get("1");
//遍历
map.forEach((k, v) -> {
System.out.println(k+"-"+v);
});

（3）源码剖析

• 哈希表默认大小和加载因子：默认大小16，加载因子0.75，加载因子表示哈希表使用了75%则进行扩容
• static final int DEFAULT_INITIAL_CAPACITY = 1 << 4; // aka 16
  static final float DEFAULT_LOAD_FACTOR = 0.75f;public HashMap(int initialCapacity, float loadFactor) {if (initialCapacity < 0)throw new IllegalArgumentException("Illegal initial capacity: " +initialCapacity);if (initialCapacity > MAXIMUM_CAPACITY)initialCapacity = MAXIMUM_CAPACITY;if (loadFactor <= 0 || Float.isNaN(loadFactor))throw new IllegalArgumentException("Illegal load factor: " +loadFactor);this.loadFactor = loadFactor;this.threshold = tableSizeFor(initialCapacity);}public HashMap(int initialCapacity) {this(initialCapacity, DEFAULT_LOAD_FACTOR);}public HashMap() {this.loadFactor = DEFAULT_LOAD_FACTOR; // all other fields defaulted}
• put方法过程：执行put 调用 hash方法，计算 key的 hash值 (h = key.hashCode()) ^ (h >>> 16)
• public V put(K key, V value) {
  //调用putVal方法return putVal(hash(key), key, value, false, true);}//真正的put方法final V putVal(int hash, K key, V value, boolean onlyIfAbsent,boolean evict) {Node<K,V>[] tab; Node<K,V> p; int n, i;//如果底层的table 数组为null, 或者 length =0 , 就扩容到16if ((tab = table) == null || (n = tab.length) == 0)n = (tab = resize()).length;//取出hash值对应的table的索引位置的Node, 如果为null, 就直接把加入的k-v, 创建成一个 Node ,加入该位置即可if ((p = tab[i = (n - 1) & hash]) == null)tab[i] = newNode(hash, key, value, null);else {Node<K,V> e; K k;//如果table的索引位置的key的hash相同和新的key的hash值相同，并满足(table现有的结点的key和准备添加的key是同一个对象||equals返回真)就认为不能加入新的k-vif (p.hash == hash &&((k = p.key) == key || (key != null && key.equals(k))))e = p;else if (p instanceof TreeNode)e = ((TreeNode<K,V>)p).putTreeVal(this, tab, hash, key, value);else {//如果找到的结点，后面是链表，就循环比较for (int binCount = 0; ; ++binCount) {if ((e = p.next) == null) {p.next = newNode(hash, key, value, null);if (binCount >= TREEIFY_THRESHOLD - 1) // -1 for 1st//加入后，判断当前链表的个数，是否已经到8个，到8个，后就调用 treeifyBin 方法进行红黑树的转换treeifyBin(tab, hash);break;}if (e.hash == hash &&((k = e.key) == key || (key != null && key.equals(k))))break;p = e;}}if (e != null) { // existing mapping for keyV oldValue = e.value;if (!onlyIfAbsent || oldValue == null)e.value = value;afterNodeAccess(e);return oldValue;}}++modCount;//如size > 临界值，就扩容if (++size > threshold)resize();afterNodeInsertion(evict);return null;}
• 树化过程：
• final void treeifyBin(Node<K,V>[] tab, int hash) {
  int n, index; Node<K,V> e;//如果table 为null ,或者大小还没有到 64，暂时不树化，而是进行扩容.if (tab == null || (n = tab.length) < MIN_TREEIFY_CAPACITY)resize();else if ((e = tab[index = (n - 1) & hash]) != null) {TreeNode<K,V> hd = null, tl = null;do {TreeNode<K,V> p = replacementTreeNode(e, null);if (tl == null)hd = p;else {p.prev = tl;tl.next = p;}tl = p;} while ((e = e.next) != null);if ((tab[index] = hd) != null)hd.treeify(tab);}}
• 扩容机制：
• final Node<K,V>[] resize() {
  Node<K,V>[] oldTab = table;int oldCap = (oldTab == null) ? 0 : oldTab.length;int oldThr = threshold;int newCap, newThr = 0;if (oldCap > 0) {if (oldCap >= MAXIMUM_CAPACITY) {threshold = Integer.MAX_VALUE;return oldTab;}else if ((newCap = oldCap << 1) < MAXIMUM_CAPACITY &&oldCap >= DEFAULT_INITIAL_CAPACITY)newThr = oldThr << 1; // double threshold}else if (oldThr > 0) // initial capacity was placed in thresholdnewCap = oldThr;else { // zero initial threshold signifies using defaultsnewCap = DEFAULT_INITIAL_CAPACITY;newThr = (int)(DEFAULT_LOAD_FACTOR * DEFAULT_INITIAL_CAPACITY);}if (newThr == 0) {float ft = (float)newCap * loadFactor;newThr = (newCap < MAXIMUM_CAPACITY && ft < (float)MAXIMUM_CAPACITY ?(int)ft : Integer.MAX_VALUE);}threshold = newThr;@SuppressWarnings({"rawtypes","unchecked"})Node<K,V>[] newTab = (Node<K,V>[])new Node[newCap];table = newTab;if (oldTab != null) {for (int j = 0; j < oldCap; ++j) {Node<K,V> e;if ((e = oldTab[j]) != null) {oldTab[j] = null;if (e.next == null)newTab[e.hash & (newCap - 1)] = e;else if (e instanceof TreeNode)((TreeNode<K,V>)e).split(this, newTab, j, oldCap);else { // preserve orderNode<K,V> loHead = null, loTail = null;Node<K,V> hiHead = null, hiTail = null;Node<K,V> next;do {next = e.next;if ((e.hash & oldCap) == 0) {if (loTail == null)loHead = e;elseloTail.next = e;loTail = e;}else {if (hiTail == null)hiHead = e;elsehiTail.next = e;hiTail = e;}} while ((e = next) != null);if (loTail != null) {loTail.next = null;newTab[j] = loHead;}if (hiTail != null) {hiTail.next = null;newTab[j + oldCap] = hiHead;}}}}}return newTab;}

4.2 HashTable

（1）集合体系

（2）基本使用

同HashMap

（3）源码剖析

• 是否线程安全：线程安全
• 值是否可以为null：不可以为null
• public synchronized V put(K key, V value) {
  // Make sure the value is not nullif (value == null) {throw new NullPointerException();}// Makes sure the key is not already in the hashtable.Entry<?,?> tab[] = table;int hash = key.hashCode();int index = (hash & 0x7FFFFFFF) % tab.length;@SuppressWarnings("unchecked")Entry<K,V> entry = (Entry<K,V>)tab[index];for(; entry != null ; entry = entry.next) {if ((entry.hash == hash) && entry.key.equals(key)) {V old = entry.value;entry.value = value;return old;}}addEntry(hash, key, value, index);return null;}

4.3 TreeMap

（1）集合体系

（2）基本使用

TreeMap treeMap = new TreeMap(new Comparator() {
@Override
public int compare(Object o1, Object o2) {
//按照Key的长度大小排序 相等时只插入一个
return ((String) o2).length() - ((String) o1).length();
}
});
treeMap.put("1", "zs");
treeMap.put("11", "ls");
treeMap.put("12", "ww");

（3）源码剖析

• 排序机制：构造方法中传入Comparator接口的匿名内部类
• public TreeMap(Comparator<? super K> comparator) {
  this.comparator = comparator;}
• public V put(K key, V value) {
  Entry<K,V> t = root;if (t == null) {compare(key, key); // type (and possibly null) checkroot = new Entry<>(key, value, null);size = 1;modCount++;return null;}int cmp;Entry<K,V> parent;// split comparator and comparable pathsComparator<? super K> cpr = comparator;if (cpr != null) {do {parent = t;cmp = cpr.compare(key, t.key);if (cmp < 0)t = t.left;else if (cmp > 0)t = t.right;elsereturn t.setValue(value);} while (t != null);}else {if (key == null)throw new NullPointerException();@SuppressWarnings("unchecked")Comparable<? super K> k = (Comparable<? super K>) key;do {parent = t;cmp = k.compareTo(t.key);if (cmp < 0)t = t.left;else if (cmp > 0)t = t.right;elsereturn t.setValue(value);} while (t != null);}Entry<K,V> e = new Entry<>(key, value, parent);if (cmp < 0)parent.left = e;elseparent.right = e;fixAfterInsertion(e);size++;modCount++;return null;}

4.4 Properties

（1）集合体系

（2）基本使用

Properties properties = new Properties();
properties.put("1", "zs");
properties.put("2", "ls");
properties.put("3", "ww");
//通过key获取对应值
properties.get("1");
//删除
properties.remove("2");

（3）源码剖析

略

4.5 LinkedHashMap

（1）集合体系

（2）基本使用

LinkedHashMap<String, Object> map = new LinkedHashMap<>();
map.put("1","zs");
map.put("2","ls");
map.get("1");

（3）源码剖析

• Entry结构：在HashMap的基础上将Entry像链表一样链接了起来
• private void linkNodeLast(LinkedHashMap.Entry<K,V> p) {
  LinkedHashMap.Entry<K,V> last = tail;tail = p;if (last == null)head = p;else {p.before = last;last.after = p;}}