/**
 * Returns a <code>Boolean</code> with a value represented by the
 * specified string.  The <code>Boolean</code> returned represents a
 * true value if the string argument is not <code>null</code>
 * and is equal, ignoring case, to the string {@code "true"}.
 *
 * @param   s   a string.
 * @return  the <code>Boolean</code> value represented by the string.
 */
public static Boolean valueOf(String s) {
    return toBoolean(s) ? TRUE : FALSE;
}

public class BigInteger extends Number implements Comparable<BigInteger> { 
   /**
     * Returns a positive BigInteger that is probably prime, with the
     * specified bitLength. The probability that a BigInteger returned
     * by this method is composite does not exceed 2<sup>-100</sup>.
     *
     */
    public static BigInteger probablePrime(int bitLength, Random rnd) {
    if (bitLength < 2)
        throw new ArithmeticException("bitLength < 2");
        // The cutoff of 95 was chosen empirically for best performance
        return (bitLength < SMALL_PRIME_THRESHOLD ?
                smallPrime(bitLength, DEFAULT_PRIME_CERTAINTY, rnd) :
                largePrime(bitLength, DEFAULT_PRIME_CERTAINTY, rnd));
    }

public abstract class EnumSet<E extends Enum<E>> extends AbstractSet<E>
    implements Cloneable, java.io.Serializable
{
    /**
     * Creates an empty enum set with the specified element type.
     *
     * @param elementType the class object of the element type for this enum
     *     set
     * @throws NullPointerException if <tt>elementType</tt> is null
     */
    public static <E extends Enum<E>> EnumSet<E> noneOf(Class<E> elementType) {
        Enum[] universe = getUniverse(elementType);
        if (universe == null)
            throw new ClassCastException(elementType + " not an enum");
        if (universe.length <= 64)
            return new RegularEnumSet<E>(elementType, universe);
        else
            return new JumboEnumSet<E>(elementType, universe);
    }
}
 
class RegularEnumSet<E extends Enum<E>> extends EnumSet<E> {
}
 
class JumboEnumSet<E extends Enum<E>> extends EnumSet<E> {
}

public class Collections {
    /**
     * Returns an unmodifiable view of the specified map.  This method
     * allows modules to provide users with "read-only" access to internal
     * maps.  Query operations on the returned map "read through"
     * to the specified map, and attempts to modify the returned
     * map, whether direct or via its collection views, result in an
     * <tt>UnsupportedOperationException</tt>.<p>
     *
     */
    public static <K,V> Map<K,V> unmodifiableMap(Map<? extends K, ? extends V> m) {
        return new UnmodifiableMap<K,V>(m);
    }
 
    private static class UnmodifiableMap<K,V> implements Map<K,V>, Serializable {
      }

public class Arrays {
    // Suppresses default constructor, ensuring non-instantiability.
    private Arrays() {
    }

public enum TimeUnit {
    MILLISECONDS {
        public long toNanos(long d)   { return x(d, C2/C0, MAX/(C2/C0)); }
        public long toMicros(long d)  { return x(d, C2/C1, MAX/(C2/C1)); }
        public long toMillis(long d)  { return d; }
        public long toSeconds(long d) { return d/(C3/C2); }
        public long toMinutes(long d) { return d/(C4/C2); }
        public long toHours(long d)   { return d/(C5/C2); }
        public long toDays(long d)    { return d/(C6/C2); }
        public long convert(long d, TimeUnit u) { return u.toMillis(d); }
        int excessNanos(long d, long m) { return 0; }
    },
    SECONDS {
       .....
    },
    MINUTES {
       .....
    },
    HOURS {
       ......
    },
    DAYS {
       .....
    };

    // TimeUnit.sleep()用来替代Thread.sleep()
    public void sleep(long timeout) throws InterruptedException {
        if (timeout > 0) {
            long ms = toMillis(timeout);
            int ns = excessNanos(timeout, ms);
            Thread.sleep(ms, ns);
        }
    }

public abstract class AbstractMap<K,V> implements Map<K,V> {
 
    /**
     * Each of these fields are initialized to contain an instance of the
     * appropriate view the first time this view is requested.  The views are
     * stateless, so there's no reason to create more than one of each.
     */
   transient volatile Set<K> keySet = null;
   public Set<K> keySet() {
    if (keySet == null) {
        keySet = new AbstractSet<K>() {
        .....
        };
    }
    return keySet;
    }    
}   

public class LinkedHashMap<K,V>
    extends HashMap<K,V>
    implements Map<K,V>
{
   /**
     * It causes newly allocated entry to get inserted at the end of the linked list and
     * removes the eldest entry if appropriate.
     */
    void addEntry(int hash, K key, V value, int bucketIndex) {
        createEntry(hash, key, value, bucketIndex);
        // Remove eldest entry if instructed, else grow capacity if appropriate
        Entry<K,V> eldest = header.after;
        if (removeEldestEntry(eldest)) {
            removeEntryForKey(eldest.key);
        } else {
            if (size >= threshold)
                resize(2 * table.length);
        }
    }
    /**
     * Returns <tt>true</tt> if this map should remove its eldest entry.
     * This method is invoked by <tt>put</tt> and <tt>putAll</tt> after
     * inserting a new entry into the map.  
     *
     * Sample use: 
     * <pre>
     *     private static final int MAX_ENTRIES = 100;
     *
     *     protected boolean removeEldestEntry(Map.Entry eldest) {
     *        return size() > MAX_ENTRIES;
     *     }
     * </pre>
     *
     */
    protected boolean removeEldestEntry(Map.Entry<K,V> eldest) {
        return false;
    }

/**
 * Returns the String representation of this BigInteger in the
 * given radix.  
 *
 */
public String toString(int radix) {
 
/**
 * Returns the decimal String representation of this BigInteger.
 */
public String toString() {
    return toString(10);
}

/**
 * Translates the decimal String representation of a BigInteger into a
 * BigInteger.  
 */
public BigInteger(String val) {
    this(val, 10);
}
/**
 * Translates the String representation of a BigInteger in the specified
 * radix into a BigInteger.  
 */
public BigInteger(String val, int radix) { 

/**
 * Returns a BigInteger whose value is {@code (-this)}.
 *
 * @return {@code -this}
 */
public BigInteger negate() {
      return new BigInteger(this.mag, -this.signum);
}

public static final BigInteger ZERO = new BigInteger(new int[0], 0);
public static final BigInteger ONE = valueOf(1);
public static final BigInteger TEN = valueOf(10);

/** Cache the hash code for the string */
private int hash; // Default to 0
 
public int hashCode() {
  int h = hash;
  int len = count;
  if (h == 0 && len > 0) {
    int off = offset;
    char val[] = value;
        for (int i = 0; i < len; i++) {
            h = 31*h + val[off++];
        }
        hash = h;
  }
  return h;
}

// Arrays  
   public static void sort(Object[] a) {  
        ...  
        ComparableTimSort.sort(a);  
    }  
  
// ComparableTimSort  
   static void sort(Object[] a, int lo, int hi) {  
        ...  
        binarySort(a, lo, hi, lo + initRunLen);  
             
   } 

//算法框架  
private static void binarySort(Object[] a, int lo, int hi, int start) {  
    assert lo <= start && start <= hi;  
    if (start == lo)  
        start++;  
    for ( ; start < hi; start++) {  
        @SuppressWarnings("unchecked")  
        Comparable<Object> pivot = (Comparable) a[start];  
  
        // Set left (and right) to the index where a[start] (pivot) belongs  
        ....  
        while (left < right) {  
            int mid = (left + right) >>> 1;  
            if (pivot.compareTo(a[mid]) < 0) //compareTo这个算法步骤，是由各个Comparable的子类定义的  
                right = mid;  
            else  
                left = mid + 1;  
        }  
        ....  
    }  
} 

 //算法框架  
 public int read(byte b[], int off, int len) throws IOException {  
        ...  
  
        int c = read();  
          
        ...  
}  
  
//算法步骤由子类实现  
public abstract int read() throws IOException;  

// JFrame  
    public void update(Graphics g) {  
        paint(g);  
    }  

public class MyFrame extends JFrame {  
    public MyFrame(){  
        super();  
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);  
        this.setSize(300,300);  
        this.setVisible(true);  
    }  
      
    @Override  
    public void paint(Graphics g){ //重定义算法步骤  
        super.paint(g);  
        g.drawString("I rule !", 100, 100);  
    }  
      
    public static void main(String[] args){  
        MyFrame frame = new MyFrame();  
    }  
  
} 

// Applet  
    public void init() { //什么也不做的hook  
    }  

// Beans  
   public static Object instantiate(ClassLoader cls, String beanName,   
                    BeanContext beanContext, AppletInitializer initializer)  
                        throws IOException, ClassNotFoundException {  
  
          
  
                // If it was deserialized then it was already init-ed.  
                // Otherwise we need to initialize it.  
  
                if (!serialized) {  
                    // We need to set a reasonable initial size, as many  
                    // applets are unhappy if they are started without  
                    // having been explicitly sized.  
                    applet.setSize(100,100);  
                    applet.init(); //调用hook  
                }  
  
                  
        }  
  
        return result;  
    }  

/**
 * Creates a <tt>FutureTask</tt> that will upon running, execute the given <tt>Callable</tt>.
 */
public FutureTask(Callable<V> callable) {
    sync = new Sync(callable);
}
 
/**
 * Creates a <tt>FutureTask</tt> that will upon running, execute the given <tt>Runnable</tt>
 */
public FutureTask(Runnable runnable, V result) {
    sync = new Sync(Executors.callable(runnable, result));
}

public static <T> Callable<T> callable(Runnable task, T result) {
    return new RunnableAdapter<T>(task, result);
}
 
/** --Adapter!--
 * A callable that runs given task and returns given result
 */
static final class RunnableAdapter<T> implements Callable<T> {  //Target
    final Runnable task; //Adaptee
    final T result;
    RunnableAdapter(Runnable  task, T result) {
        this.task = task;
        this.result = result;
    }
    public T call() {
        task.run();
        return result;
    }
}

   public <T> Future<T> submit(Runnable task, T result) {
        if (task == null) throw new NullPointerException();
        RunnableFuture<T> ftask = newTaskFor(task, result);
        execute(ftask);
        return ftask;
    }
    protected <T> RunnableFuture<T> newTaskFor(Runnable runnable, T value) {
        return new FutureTask<T>(runnable, value);
    }