java编程思想第四版第十一章习题

1. 第一题

   package net.mindview.holding.test1;
   
   import java.util.ArrayList;
   import java.util.List;
   
   /**
    * 沙鼠
    * @author samsung
    *
    */
   public class Gerbil {
       static int counter;
       int gerbilNumber;
   
       public Gerbil(){
           this.gerbilNumber = counter ++;
       }
   
       public String hop(){
   
           return "沙鼠的号码:"+gerbilNumber + ",正在跳跃";
       }
   
       public static void main(String[] args) {
           List<Gerbil> list = new ArrayList<Gerbil>();
           list.add(new Gerbil());
           list.add(new Gerbil());
           list.add(new Gerbil());
           list.add(new Gerbil());
           for(Gerbil g: list){
               System.out.println(g.hop());
           }
       }
   }

   运行结果

   沙鼠的号码:,正在跳跃
   沙鼠的号码:,正在跳跃
   沙鼠的号码:,正在跳跃
   沙鼠的号码:,正在跳跃

2. 第二题

   package net.mindview.holding.test2;
   
   import java.util.HashSet;
   import java.util.Set;
   
   public class SimpleCollection {
   
       public static void main(String[] args) {
           Set<Integer> c = new HashSet<Integer>();
           for(int i = ; i < ; i++){
               c.add(i);
           }
           for(Integer i: c){
               System.out.print(i + ",");
           }
       }
   
   }

3. 第三题

   package net.mindview.holding.test3;
   
   import java.util.ArrayList;
   import java.util.List;
   
   /**
    * 选择器
    */
   interface Selector {
       //是否结束
       boolean end();
       //当前
       Object current();
       //下一个
       void next();
   }
   
   /**
    * 顺序
    */
   public class Sequence {
       //数组是有限制的,而集合时无限制的.
       //private Object[] items;
       private List<Object> items;
       private int next = ;
       //定义数组的个数
       public Sequence(){
           items = new ArrayList<Object>();
       }
       //添加
       public void add(Object x){
           items.add(x);
       }
   
       //内部类--顺序选择器
       private class SequenceSelector implements Selector {
           //选择器最开始指向第一个元素
           private int i = ;
           @Override
           public boolean end() {
               return i == (items.size());
           }
           /**
            * 新增方法: 在内部类中引用外部类
            */
           public Sequence outer(){
               return Sequence.this;
           }
   
           @Override
           public Object current() {
               return items.get(i);
           }
   
           @Override
           public void next() {
               if(i<items.size()){
                   i++;
               }
           }
       }
   
       public Selector selector() {
           return new SequenceSelector();
       }
   
       public static void main(String[] args) {
           Sequence s = new Sequence();
           for(int i=; i<; i++){
               s.add("对象"+i);
           }
           Selector selector = s.selector();
           while(!selector.end()){
               System.out.print(selector.current());
               selector.next();
           }
       }
   
   }

   结果

   对象0对象1对象2对象3对象4对象5对象6对象7对象8对象9

   分析： 这个案例的重点是， 数组瘦受限制的， 集合是没有元素个数限制的。 因此，可以任意添加元素的意思就是：将数组替代为集合。

4. 第四题

   package net.mindview.holding.test4;
   
   import java.util.ArrayList;
   import java.util.Arrays;
   import java.util.Collection;
   import java.util.HashSet;
   import java.util.LinkedHashSet;
   import java.util.LinkedList;
   import java.util.TreeSet;
   class MoiveNameGenerator {
       String[] moives = {"Snow White", "Star Wars", "White Princple", "Dream","My Mother", "The Forest", "My Grandpa"};
       int next;
       public String next(){
           String moive = moives[next];
           //电影名用完之后, 循环到这个字符列表的开始处
           next = (next+) % moives.length;
           return moive;
       }
   
   }
   public class MoiveGenerator {
       MoiveNameGenerator moiveNameGenerator = new MoiveNameGenerator();
       public String[] fill(String[] arr){
           for(int i=; i<arr.length; i++){
               arr[i] = moiveNameGenerator.next();
           }
           return arr;
       }
   
       public Collection fill(Collection col){
           for(int i=; i<; i++){
               col.add(moiveNameGenerator.next());
           }
           return col;
       }
   
       public static void main(String[] args) {
           MoiveGenerator moiveGenerator = new MoiveGenerator();
           System.out.println(Arrays.toString(moiveGenerator.fill(new String[])));
           System.out.println(moiveGenerator.fill(new ArrayList<String>()));
           System.out.println(moiveGenerator.fill(new LinkedList<String>()));
           System.out.println(moiveGenerator.fill(new HashSet<String>()));
           System.out.println(moiveGenerator.fill(new LinkedHashSet<String>()));
           System.out.println(moiveGenerator.fill(new TreeSet<String>()));
       }
   }

   运行结果：

   [Snow White, Star Wars, White Princple, Dream, My Mother]
   [The Forest, My Grandpa, Snow White, Star Wars, White Princple]
   [Dream, My Mother, The Forest, My Grandpa, Snow White]
   [My Mother, Star Wars, The Forest, Dream, White Princple]
   [My Grandpa, Snow White, Star Wars, White Princple, Dream]
   [My Grandpa, My Mother, Snow White, Star Wars, The Forest]

5. dff
6. af
7. a
8. fa
9. fda
10. sf
11. af
12. as
13. fa
14. fa

15. 栈在编程语言中,经常用来对表达式求值。请使用net.mindview.util.Stack对下面的表达式求值。 其中“+”表示将后面的字母压入栈，“-”表示将栈顶的字母押出栈。并打印他们。

    package net.mindview.holding;
    
    import java.util.LinkedList;
    
    /**
     * 模拟栈
     */
    public class Stack<T> {
        private LinkedList<T> storage = new LinkedList<T>();
    
        //推入
        public void push(T v){
            storage.addFirst(v);
        }
    
        public T peek(){
            return storage.getFirst();
        }
    
        //取出
        public T pop(){
            return storage.removeFirst();
        }
    
        public boolean empty(){
            return storage.isEmpty();
        }
    
        public String toString(){
            return storage.toString();
        }
    
    }

    package net.mindview.holding.test15;
    
    import java.util.Stack;
    
    /**
     * 栈在编程语言中,经常用来对表达式求值。请使用net.mindview.util.Stack对下面的表达式求值。
     * 其中“+”表示将后面的字母压入栈，“-”表示将栈顶的字母押出栈。并打印他们。
     * @author samsung
     *
     */
    public class Test15 {
        Stack<Character> stac = new Stack<Character>();
        //计算
        public void eval(String str){
            char[] chars = str.toCharArray();
            for(int i=; i<chars.length; i++){
                char c = chars[i++];
                //遇到+号把字符入栈
                switch (c){
                    case '+':
                        System.out.println("入栈:"+stac.push(chars[i]));
                        break;
                    case '-':
                        System.out.println("出栈:"+stac.pop());
                        break;
                }
            }
        }
    
        public static void main(String[] args) {
            Test15 t = new Test15();
            String str = "+U+n+c---+e+r+t---+a-+i-+n+t+y---+ -+r+u--+l+e+s--";
            t.eval(str);
        }
    }

16. fda
17. fa
18. fa
19. dfa
20. fa
21. df
22. asfd
23. afa
24. fa
25. fa
26. fa
27. 二十七题

    package net.mindview.holding.test27;
    
    import java.util.LinkedList;
    import java.util.Queue;
    
    //消息
    class Command {
        String str;
        public Command(String str){
            this.str = str;
        }
        public void operation(){
            System.out.println(str);
        }
    }
    
    //生产者
    class Producter{
        //生产者生成消息
        public Queue<Command> produce(Queue<Command> qc){
            qc.offer(new Command("A"));
            qc.offer(new Command("AB"));
            qc.offer(new Command("ABC"));
            qc.offer(new Command("VFA"));
            qc.offer(new Command("SDA"));
            return qc;
        }
    }
    
    //消费者
    class Customer {
        //消费者消费消息
        public void custom(Queue<Command> queue){
            while(queue.peek() != null){
                queue.remove().operation();
            }
        }
    }
    
    public class Test27 {
        public static void main(String[] args) {
            Queue<Command> qc = new LinkedList<Command>();
            Producter producter = new Producter();
            Queue<Command> qcc = producter.produce(qc);
            new Customer().custom(qcc);
    
        }
    }

    运行结果:

    A
    AB
    ABC
    VFA
    SDA

28. fa
29. 第三十一题

    package net.mindview.holding.test31;
    
    import java.util.Iterator;
    import java.util.Random;
    
    //形状
    class Shape {
        public void draw() {
        }
    
        public void erase() {
        }
    }
    
    // 圆形
    class Cycle1 extends Shape {
    
        @Override
        public void draw() {
            System.out.println("draw cycle");
        }
    
        @Override
        public void erase() {
            System.out.println("erase cycle");
        }
    
    }
    
    class Square extends Shape {
        @Override
        public void draw() {
            System.out.println("draw Square");
        }
    
        @Override
        public void erase() {
            System.out.println("draw Square");
        }
    }
    
    // 矩形
    class Triangle extends Shape {
        @Override
        public void draw() {
            System.out.println("draw Triangle");
        }
    
        @Override
        public void erase() {
            System.out.println("draw Triangle");
        }
    }
    
    // 梯形
    class Trapezoid extends Shape {
        @Override
        public void draw() {
            System.out.println("draw Trapezoid");
        }
    
        @Override
        public void erase() {
            System.out.println("draw Trapezoid");
        }
    }
    
    class RandomShapeFactory implements Iterable<Shape> {
        Random random = new Random();
    
        private final int quantity;
    
        public RandomShapeFactory(int quantity) {
            this.quantity= quantity;
        }
    
        // 下面画什么形状呢
        public Shape nextShape() {
            switch (random.nextInt()) {
            default:
            case :
                return new Cycle1();
            case :
                return new Square();
            case :
                return new Triangle();
            case :
                return new Trapezoid();
            }
        }
    
        @Override
        public Iterator<Shape> iterator() {
            return new Iterator<Shape>() {
                private int count = ;
    
                @Override
                public boolean hasNext() {
                    return count < quantity;
                }
    
                @Override
                public Shape next() {
                    ++count;
                    return nextShape();
                }
    
                @Override
                public void remove() {
    
                }
            };
        }
    }
    
    public class Shapes {
        public static void main(String[] args) {
            RandomShapeFactory rd = new RandomShapeFactory();
            for (Shape s : rd) {
                System.out.println(s.getClass().getSimpleName());
            }
    
        }
    
    }

    运行结果

    Triangle
    Square
    Triangle
    Cycle1
    Cycle1
    Triangle
    Cycle1
    Square
    Triangle

30. f
31. afda