Java编程思想之集合操作

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Collection: [add, addAll, clear, contains, containsAll, equals, hashCode, isEmpty, iterator, remove, removeAll, retainAll, size, toArray]
Interfaces in Collection: [Iterable]
Set extends Collection, adds: []
Interfaces in Set: [Collection]
HashSet extends Set, adds: []
Interfaces in HashSet: [Set, Cloneable, Serializable]
LinkedHashSet extends HashSet, adds: []
Interfaces in LinkedHashSet: [Set, Cloneable, Serializable]
TreeSet extends Set, adds: [pollLast, navigableHeadSet, descendingIterator, lower, headSet, ceiling, pollFirst, subSet, navigableTailSet, comparator, first, floor, last, navigableSubSet, higher, tailSet]
Interfaces in TreeSet: [NavigableSet, Cloneable, Serializable]
List extends Collection, adds: [listIterator, indexOf, get, subList, set, lastIndexOf]
Interfaces in List: [Collection]
ArrayList extends List, adds: [ensureCapacity, trimToSize]
Interfaces in ArrayList: [List, RandomAccess, Cloneable, Serializable]
LinkedList extends List, adds: [pollLast, offer, descendingIterator, addFirst, peekLast, removeFirst, peekFirst, removeLast, getLast, pollFirst, pop, poll, addLast, removeFirstOccurrence, getFirst, element, peek, offerLast, push, offerFirst, removeLastOccurrence]
Interfaces in LinkedList: [List, Deque, Cloneable, Serializable]
Queue extends Collection, adds: [offer, element, peek, poll]
Interfaces in Queue: [Collection]
PriorityQueue extends Queue, adds: [comparator]
Interfaces in PriorityQueue: [Serializable]
Map: [clear, containsKey, containsValue, entrySet, equals, get, hashCode, isEmpty, keySet, put, putAll, remove, size, values]
HashMap extends Map, adds: []
Interfaces in HashMap: [Map, Cloneable, Serializable]
LinkedHashMap extends HashMap, adds: []
Interfaces in LinkedHashMap: [Map]
SortedMap extends Map, adds: [subMap, comparator, firstKey, lastKey, headMap, tailMap]
Interfaces in SortedMap: [Map]
TreeMap extends Map, adds: [descendingEntrySet, subMap, pollLastEntry, lastKey, floorEntry, lastEntry, lowerKey, navigableHeadMap, navigableTailMap, descendingKeySet, tailMap, ceilingEntry, higherKey, pollFirstEntry, comparator, firstKey, floorKey, higherEntry, firstEntry, navigableSubMap, headMap, lowerEntry, ceilingKey]
Interfaces in TreeMap: [NavigableMap, Cloneable, Serializable]

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package holding;
//: holding/ListFeatures.java
import typeinfo.pets.*;
import java.util.*;
import static net.mindview.util.Print.*;

public class ListFeatures {
  public static void main(String[] args) {
    Random rand = new Random(47);
    List<Pet> pets = Pets.arrayList(7);
    print("1: " + pets);
    Hamster h = new Hamster();
    pets.add(h); // Automatically resizes
    print("2: " + pets);
    print("3: " + pets.contains(h));
    pets.remove(h); // Remove by object
    Pet p = pets.get(2);
    print("4: " +  p + " " + pets.indexOf(p));
    Pet cymric = new Cymric();
    print("5: " + pets.indexOf(cymric));
    print("6: " + pets.remove(cymric));
    // Must be the exact object:
    print("7: " + pets.remove(p));
    print("8: " + pets);
    pets.add(3, new Mouse()); // Insert at an index
    print("9: " + pets);
    List<Pet> sub = pets.subList(1, 4);
    print("subList: " + sub);
    print("10: " + pets.containsAll(sub));
    Collections.sort(sub); // In-place sort
    print("sorted subList: " + sub);
    // Order is not important in containsAll():
    print("11: " + pets.containsAll(sub));
    Collections.shuffle(sub, rand); // Mix it up
    print("shuffled subList: " + sub);
    print("12: " + pets.containsAll(sub));
    List<Pet> copy = new ArrayList<Pet>(pets);
    sub = Arrays.asList(pets.get(1), pets.get(4));
    print("sub: " + sub);
    copy.retainAll(sub);
    print("13: " + copy);
    copy = new ArrayList<Pet>(pets); // Get a fresh copy
    copy.remove(2); // Remove by index
    print("14: " + copy);
    copy.removeAll(sub); // Only removes exact objects
    print("15: " + copy);
    copy.set(1, new Mouse()); // Replace an element
    print("16: " + copy);
    copy.addAll(2, sub); // Insert a list in the middle
    print("17: " + copy);
    print("18: " + pets.isEmpty());
    pets.clear(); // Remove all elements
    print("19: " + pets);
    print("20: " + pets.isEmpty());
    pets.addAll(Pets.arrayList(4));
    print("21: " + pets);
    Object[] o = pets.toArray();
    print("22: " + o[3]);
    Pet[] pa = pets.toArray(new Pet[0]);
    print("23: " + pa[3].id());
  }
} /* Output:
1: [Rat, Manx, Cymric, Mutt, Pug, Cymric, Pug]
2: [Rat, Manx, Cymric, Mutt, Pug, Cymric, Pug, Hamster]
3: true
4: Cymric 2
5: -1
6: false
7: true
8: [Rat, Manx, Mutt, Pug, Cymric, Pug]
9: [Rat, Manx, Mutt, Mouse, Pug, Cymric, Pug]
subList: [Manx, Mutt, Mouse]
10: true
sorted subList: [Manx, Mouse, Mutt]
11: true
shuffled subList: [Mouse, Manx, Mutt]
12: true
sub: [Mouse, Pug]
13: [Mouse, Pug]
14: [Rat, Mouse, Mutt, Pug, Cymric, Pug]
15: [Rat, Mutt, Cymric, Pug]
16: [Rat, Mouse, Cymric, Pug]
17: [Rat, Mouse, Mouse, Pug, Cymric, Pug]
18: false
19: []
20: true
21: [Manx, Cymric, Rat, EgyptianMau]
22: EgyptianMau
23: 14
*///:~

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package holding;
//: holding/SimpleIteration.java
import typeinfo.pets.*;
import java.util.*;

public class SimpleIteration {
  public static void main(String[] args) {
    List<Pet> pets = Pets.arrayList(12);
    Iterator<Pet> it = pets.iterator();
    while(it.hasNext()) {
      Pet p = it.next();
      System.out.print(p.id() + ":" + p + " ");
    }
    System.out.println();
    // A simpler approach, when possible:
    for(Pet p : pets)
      System.out.print(p.id() + ":" + p + " ");
    System.out.println();	
    // An Iterator can also remove elements:
    it = pets.iterator();
    for(int i = 0; i < 6; i++) {
      it.next();
      it.remove();
    }
    System.out.println(pets);
  }
} /* Output:
0:Rat 1:Manx 2:Cymric 3:Mutt 4:Pug 5:Cymric 6:Pug 7:Manx 8:Cymric 9:Rat 10:EgyptianMau 11:Hamster
0:Rat 1:Manx 2:Cymric 3:Mutt 4:Pug 5:Cymric 6:Pug 7:Manx 8:Cymric 9:Rat 10:EgyptianMau 11:Hamster
[Pug, Manx, Cymric, Rat, EgyptianMau, Hamster]
*///:~

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package holding;
//: holding/ListIteration.java
import typeinfo.pets.*;
import java.util.*;

public class ListIteration {
  public static void main(String[] args) {
    List<Pet> pets = Pets.arrayList(8);
    ListIterator<Pet> it = pets.listIterator();
    while(it.hasNext())
      System.out.print(it.next() + ", " + it.nextIndex() +
        ", " + it.previousIndex() + "; ");
    System.out.println();
    // Backwards:
    while(it.hasPrevious())
      System.out.print(it.previous().id() + " ");
    System.out.println();
    System.out.println(pets);	
    it = pets.listIterator(3);
    while(it.hasNext()) {
      it.next();
      it.set(Pets.randomPet());
    }
    System.out.println(pets);
  }
} /* Output:
Rat, 1, 0; Manx, 2, 1; Cymric, 3, 2; Mutt, 4, 3; Pug, 5, 4; Cymric, 6, 5; Pug, 7, 6; Manx, 8, 7;
7 6 5 4 3 2 1 0
[Rat, Manx, Cymric, Mutt, Pug, Cymric, Pug, Manx]
[Rat, Manx, Cymric, Cymric, Rat, EgyptianMau, Hamster, EgyptianMau]
*///:~

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package holding;
//: holding/LinkedListFeatures.java
import typeinfo.pets.*;
import java.util.*;
import static net.mindview.util.Print.*;

public class LinkedListFeatures {
  public static void main(String[] args) {
    LinkedList<Pet> pets =
      new LinkedList<Pet>(Pets.arrayList(5));
    print(pets);
    // Identical:
    print("pets.getFirst(): " + pets.getFirst());
    print("pets.element(): " + pets.element());
    // Only differs in empty-list behavior:
    print("pets.peek(): " + pets.peek());
    // Identical; remove and return the first element:
    print("pets.remove(): " + pets.remove());
    print("pets.removeFirst(): " + pets.removeFirst());
    // Only differs in empty-list behavior:
    print("pets.poll(): " + pets.poll());
    print(pets);
    pets.addFirst(new Rat());
    print("After addFirst(): " + pets);
    pets.offer(Pets.randomPet());
    print("After offer(): " + pets);
    pets.add(Pets.randomPet());
    print("After add(): " + pets);
    pets.addLast(new Hamster());
    print("After addLast(): " + pets);
    print("pets.removeLast(): " + pets.removeLast());
  }
} /* Output:
[Rat, Manx, Cymric, Mutt, Pug]
pets.getFirst(): Rat
pets.element(): Rat
pets.peek(): Rat
pets.remove(): Rat
pets.removeFirst(): Manx
pets.poll(): Cymric
[Mutt, Pug]
After addFirst(): [Rat, Mutt, Pug]
After offer(): [Rat, Mutt, Pug, Cymric]
After add(): [Rat, Mutt, Pug, Cymric, Pug]
After addLast(): [Rat, Mutt, Pug, Cymric, Pug, Hamster]
pets.removeLast(): Hamster
*///:~

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Set<String> tset=new TreeSet<String>(String.CASE_INSENTIVE_ORDER);

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package holding;
//: holding/SetOperations.java
import java.util.*;
import static net.mindview.util.Print.*;

public class SetOperations {
  public static void main(String[] args) {
    Set<String> set1 = new HashSet<String>();
    Collections.addAll(set1,
      "A B C D E F G H I J K L".split(" "));
    set1.add("M");
    print("H: " + set1.contains("H"));
    print("N: " + set1.contains("N"));
    Set<String> set2 = new HashSet<String>();
    Collections.addAll(set2, "H I J K L".split(" "));
    print("set2 in set1: " + set1.containsAll(set2));
    set1.remove("H");
    print("set1: " + set1);
    print("set2 in set1: " + set1.containsAll(set2));
    set1.removeAll(set2);
    print("set2 removed from set1: " + set1);
    Collections.addAll(set1, "X Y Z".split(" "));
    print("'X Y Z' added to set1: " + set1);
  }
} /* Output:
H: true
N: false
set2 in set1: true
set1: [D, K, C, B, L, G, I, M, A, F, J, E]
set2 in set1: false
set2 removed from set1: [D, C, B, G, M, A, F, E]
'X Y Z' added to set1: [Z, D, C, B, G, M, A, F, Y, X, E]
*///:~

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package holding;
//: holding/PetMap.java
import typeinfo.pets.*;
import java.util.*;
import static net.mindview.util.Print.*;

public class PetMap {
  public static void main(String[] args) {
    Map<String,Pet> petMap = new HashMap<String,Pet>();
    petMap.put("My Cat", new Cat("Molly"));
    petMap.put("My Dog", new Dog("Ginger"));
    petMap.put("My Hamster", new Hamster("Bosco"));
    print(petMap);
    Pet dog = petMap.get("My Dog");
    print(dog);
    print(petMap.containsKey("My Dog"));
    print(petMap.containsValue(dog));
  }
} /* Output:
{My Cat=Cat Molly, My Hamster=Hamster Bosco, My Dog=Dog Ginger}
Dog Ginger
true
true
*///:~

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//: holding/MapOfList.java
package holding;
import typeinfo.pets.*;
import java.util.*;
import static net.mindview.util.Print.*;

public class MapOfList {
  public static Map<Person, List<? extends Pet>>
    petPeople = new HashMap<Person, List<? extends Pet>>();
  static {
    petPeople.put(new Person("Dawn"),
      Arrays.asList(new Cymric("Molly"),new Mutt("Spot")));
    petPeople.put(new Person("Kate"),
      Arrays.asList(new Cat("Shackleton"),
        new Cat("Elsie May"), new Dog("Margrett")));
    petPeople.put(new Person("Marilyn"),
      Arrays.asList(
       new Pug("Louie aka Louis Snorkelstein Dupree"),
       new Cat("Stanford aka Stinky el Negro"),
       new Cat("Pinkola")));	
    petPeople.put(new Person("Luke"),
      Arrays.asList(new Rat("Fuzzy"), new Rat("Fizzy")));
    petPeople.put(new Person("Isaac"),
      Arrays.asList(new Rat("Freckly")));
  }
  public static void main(String[] args) {
    print("People: " + petPeople.keySet());
    print("Pets: " + petPeople.values());
    for(Person person : petPeople.keySet()) {
      print(person + " has:");
      for(Pet pet : petPeople.get(person))
        print("    " + pet);
    }
  }
} /* Output:	
People: [Person Luke, Person Marilyn, Person Isaac, Person Dawn, Person Kate]
Pets: [[Rat Fuzzy, Rat Fizzy], [Pug Louie aka Louis Snorkelstein Dupree, Cat Stanford aka Stinky el Negro, Cat Pinkola], [Rat Freckly], [Cymric Molly, Mutt Spot], [Cat Shackleton, Cat Elsie May, Dog Margrett]]
Person Luke has:
    Rat Fuzzy
    Rat Fizzy
Person Marilyn has:
    Pug Louie aka Louis Snorkelstein Dupree
    Cat Stanford aka Stinky el Negro
    Cat Pinkola
Person Isaac has:
    Rat Freckly
Person Dawn has:
    Cymric Molly
    Mutt Spot
Person Kate has:
    Cat Shackleton
    Cat Elsie May
    Dog Margrett
*///:~

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package holding;
//: holding/QueueDemo.java
// Upcasting to a Queue from a LinkedList.
import java.util.*;

public class QueueDemo {
  public static void printQ(Queue queue) {
    while(queue.peek() != null)
      System.out.print(queue.remove() + " ");
    System.out.println();
  }
  public static void main(String[] args) {
    Queue<Integer> queue = new LinkedList<Integer>();
    Random rand = new Random(47);
    for(int i = 0; i < 10; i++)
      queue.offer(rand.nextInt(i + 10));
    printQ(queue);
    Queue<Character> qc = new LinkedList<Character>();
    for(char c : "Brontosaurus".toCharArray())
      qc.offer(c);
    printQ(qc);
  }
} /* Output:
8 1 1 1 5 14 3 1 0 1
B r o n t o s a u r u s
*///:~

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package holding;
//: holding/PriorityQueueDemo.java
import java.util.*;

public class PriorityQueueDemo {
  public static void main(String[] args) {
    PriorityQueue<Integer> priorityQueue =
      new PriorityQueue<Integer>();
    Random rand = new Random(47);
    for(int i = 0; i < 10; i++)
      priorityQueue.offer(rand.nextInt(i + 10));
    QueueDemo.printQ(priorityQueue);

    List<Integer> ints = Arrays.asList(25, 22, 20,
      18, 14, 9, 3, 1, 1, 2, 3, 9, 14, 18, 21, 23, 25);
    priorityQueue = new PriorityQueue<Integer>(ints);
    QueueDemo.printQ(priorityQueue);
    priorityQueue = new PriorityQueue<Integer>(
        ints.size(), Collections.reverseOrder());
    priorityQueue.addAll(ints);
    QueueDemo.printQ(priorityQueue);

    String fact = "EDUCATION SHOULD ESCHEW OBFUSCATION";
    List<String> strings = Arrays.asList(fact.split(""));
    PriorityQueue<String> stringPQ =
      new PriorityQueue<String>(strings);
    QueueDemo.printQ(stringPQ);
    stringPQ = new PriorityQueue<String>(
      strings.size(), Collections.reverseOrder());
    stringPQ.addAll(strings);
    QueueDemo.printQ(stringPQ);

    Set<Character> charSet = new HashSet<Character>();
    for(char c : fact.toCharArray())
      charSet.add(c); // Autoboxing
    PriorityQueue<Character> characterPQ =
      new PriorityQueue<Character>(charSet);
    QueueDemo.printQ(characterPQ);
  }
} /* Output:
0 1 1 1 1 1 3 5 8 14
1 1 2 3 3 9 9 14 14 18 18 20 21 22 23 25 25
25 25 23 22 21 20 18 18 14 14 9 9 3 3 2 1 1
       A A B C C C D D E E E F H H I I L N N O O O O S S S T T U U U W
W U U U T T S S S O O O O N N L I I H H F E E E D D C C C B A A
  A B C D E F H I L N O S T U W
*///:~

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package holding;
//: holding/CollectionSequence.java
import typeinfo.pets.*;
import java.util.*;

public class CollectionSequence
extends AbstractCollection<Pet> {
  private Pet[] pets = Pets.createArray(8);
  public int size() { return pets.length; }
  public Iterator<Pet> iterator() {
    return new Iterator<Pet>() {
      private int index = 0;
      public boolean hasNext() {
        return index < pets.length;
      }
      public Pet next() { return pets[index++]; }
      public void remove() { // Not implemented
        throw new UnsupportedOperationException();
      }
    };
  }	
  public static void main(String[] args) {
    CollectionSequence c = new CollectionSequence();
    InterfaceVsIterator.display(c);
    InterfaceVsIterator.display(c.iterator());
  }
} /* Output:
0:Rat 1:Manx 2:Cymric 3:Mutt 4:Pug 5:Cymric 6:Pug 7:Manx
0:Rat 1:Manx 2:Cymric 3:Mutt 4:Pug 5:Cymric 6:Pug 7:Manx
*///:~

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package holding;
//: holding/NonCollectionSequence.java
import typeinfo.pets.*;
import java.util.*;

class PetSequence {
  protected Pet[] pets = Pets.createArray(8);
}

public class NonCollectionSequence extends PetSequence {
  public Iterator<Pet> iterator() {
    return new Iterator<Pet>() {
      private int index = 0;
      public boolean hasNext() {
        return index < pets.length;
      }
      public Pet next() { return pets[index++]; }
      public void remove() { // Not implemented
        throw new UnsupportedOperationException();
      }
    };
  }
  public static void main(String[] args) {
    NonCollectionSequence nc = new NonCollectionSequence();
    InterfaceVsIterator.display(nc.iterator());
  }
} /* Output:
0:Rat 1:Manx 2:Cymric 3:Mutt 4:Pug 5:Cymric 6:Pug 7:Manx
*///:~

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package holding;
//: holding/IterableClass.java
// Anything Iterable works with foreach.
import java.util.*;

public class IterableClass implements Iterable<String> {
  protected String[] words = ("And that is how " +
    "we know the Earth to be banana-shaped.").split(" ");
  public Iterator<String> iterator() {
    return new Iterator<String>() {
      private int index = 0;
      public boolean hasNext() {
        return index < words.length;
      }
      public String next() { return words[index++]; }
      public void remove() { // Not implemented
        throw new UnsupportedOperationException();
      }
    };
  }	
  public static void main(String[] args) {
    for(String s : new IterableClass())
      System.out.print(s + " ");
  }
} /* Output:
And that is how we know the Earth to be banana-shaped.
*///:~

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package holding;
//: holding/ArrayIsNotIterable.java
import java.util.*;

public class ArrayIsNotIterable {
  static <T> void test(Iterable<T> ib) {
    for(T t : ib)
      System.out.print(t + " ");
  }
  public static void main(String[] args) {
    test(Arrays.asList(1, 2, 3));
    String[] strings = { "A", "B", "C" };
    // An array works in foreach, but it's not Iterable:
    //! test(strings);
    // You must explicitly convert it to an Iterable:
    test(Arrays.asList(strings));
  }
} /* Output:
1 2 3 A B C
*///:~

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package holding;
//: holding/AdapterMethodIdiom.java
// The "Adapter Method" idiom allows you to use foreach
// with additional kinds of Iterables.
import java.util.*;

class ReversibleArrayList<T> extends ArrayList<T> {
  public ReversibleArrayList(Collection<T> c) { super(c); }
  public Iterable<T> reversed() {
    return new Iterable<T>() {
      public Iterator<T> iterator() {
        return new Iterator<T>() {
          int current = size() - 1;
          public boolean hasNext() { return current > -1; }
          public T next() { return get(current--); }
          public void remove() { // Not implemented
            throw new UnsupportedOperationException();
          }
        };
      }
    };
  }
}	

public class AdapterMethodIdiom {
  public static void main(String[] args) {
    ReversibleArrayList<String> ral =
      new ReversibleArrayList<String>(
        Arrays.asList("To be or not to be".split(" ")));
    // Grabs the ordinary iterator via iterator():
    for(String s : ral)
      System.out.print(s + " ");
    System.out.println();
    // Hand it the Iterable of your choice
    for(String s : ral.reversed())
      System.out.print(s + " ");
  }
} /* Output:
To be or not to be
be to not or be To
*///:~