JavaSE编码试题强化练习4

1.编写一个Worker类，为Worker类添加相应的代码，使得Worker对象能正确放入TreeSet中。并编写相应的测试代码。

/**
 * Worker类
 */
public class Worker implements Comparable<Worker>{
  /**
   * 私有属性
   */
  private String name;
  private int age;
  private double salary;
  /**
   * 构造方法
   */
  public Worker() {
  }

  public Worker(String name, int age, double salary) {
    this.name = name;
    this.age = age;
    this.salary = salary;
  }
  /**
   * getter setter方法
   */
  public String getName() {
    return name;
  }

  public void setName(String name) {
    this.name = name;
  }

  public int getAge() {
    return age;
  }

  public void setAge(int age) {
    this.age = age;
  }

  public double getSalary() {
    return salary;
  }

  public void setSalary(double salary) {
    this.salary = salary;
  }

  /**
   * 重写toString方法
   */
 public String toString(){
    return "工人信息 : { "+"姓名 = "+name+","+"年龄 = "+age+","+"薪水 = "+salary+" }";
 }

  /**
   * 重写compareTo方法：按年龄从小到大排序，年龄相同按名字的字典顺序排列
   */
  @Override
  public int compareTo(Worker other) {
    if (this.age != other.age){
      return this.age - other.age;
    }else {
      return this.name.compareTo(other.getName());
    }
  }
}

/**
 * 测试类
 */
public class TestWorker {
  public static void main(String[] args) {
    /**
     * 创建Worker对象，通过构造方法完成赋值
     */
    Worker w1 = new Worker("F",27,5500);
    Worker w2 = new Worker("E",28,6500);
    Worker w3 = new Worker("B",26,5800);
    Worker w4 = new Worker("A",26,5300);
    /**
     * 创建TreeSet集合存放工人数据信息
     */
    Set<Worker> set = new TreeSet<Worker>();
    set.add(w1);
    set.add(w2);
    set.add(w3);
    set.add(w4);
    /**
     * 遍历Set，输出结果
     */
    for(Worker w : set){
      System.out.println(w);
    }
  }
}

运行结果：

2.设计一个多线程的程序如下：设计一个火车售票模拟程序。假如火车站要有100张火车票要卖出，现在有10个售票窗口同时售票，用10个线程模拟这10个售票窗口的售票情况。

/**
 * 定义售票类实现Runnable接口
 */
public class SaleTicket implements Runnable {
  /**
   * 定义初始变量
   * total--总票数
   * count--票号(从0开始)
   */
  public int total = 100;
  public int count = 0;

  /**
   * 重写run()方法
   */
  @Override
  public void run() {
    while (total > 0){
      synchronized (this){
        if (total > 0){
          try {
            Thread.sleep(20);
          } catch (InterruptedException e) {
            e.printStackTrace();
          }
          /**
           * 票号++
           * 总票数--
           */
          count++;
          total--;
          System.out.println(Thread.currentThread().getName()+"售出票号为："+count+
            " 的票"+"当前余票为："+total);
        }
      }
    }
  }
}

/**
 * 测试类
 */
public class TestSaleTicket {
  public static void main(String[] args) {
    /**
     * 创建线程对象，启动线程
     */
    SaleTicket st = new SaleTicket();
    /**
     * 使用循环创建启动线程
     */
    for (int i = 1;i <= 5;i++){
      Thread t = new Thread(st,i+"号售票窗口");
      t.start();
    }
    /**
     * 也可以手动创建5个线程并启动，代码稍显复杂
     */
    SaleTicket st1 = new SaleTicket();
    Thread t1 = new Thread(st1);
    Thread t2 = new Thread(st1);
    Thread t3 = new Thread(st1);
    Thread t4 = new Thread(st1);
    Thread t5 = new Thread(st1);
    t1.setName("窗口6");
    t2.setName("窗口7");
    t3.setName("窗口8");
    t4.setName("窗口9");
    t5.setName("窗口10");
    t1.start();
    t2.start();
    t3.start();
    t4.start();
    t5.start();
  }
}

运行结果：

**各线程随机执行售票功能

3.对一个数组进行折半查找，使用递归和非递归实现。

/**
 * 递归实现数组的折半查找
 */
public class TestRecursionBinarySearch {
  public static void main(String[] args) {
    int[] array = {1,2,3,4,5,6,7};
    int key = 1;
    int index = recursionBinarySearch(array,key);
    System.out.println(key+"的索引是"+index);
  }
  public static int recursionBinarySearch(int[] arr,int key){
    int start = 0;
    int end = arr.length - 1;
    return recursionBinarySearch(arr,start,end,key);
  }

  private static int recursionBinarySearch(int[] arr, int start, int end, int key) {
    /**
     * 递归的结束条件
     */
    if (start > end){
      return -1;
    }
    /**
     * 计算中间索引并获得其值
     */
    int mid = (start + end) / 2;
    int value = arr[mid];
    /**
     * 进行比较查询
     */
    if (key > value){
      start = mid + 1;
      return recursionBinarySearch(arr,start,end,key);
    }else if (key < value){
      end = mid - 1;
      return recursionBinarySearch(arr,start,end,key);
    }else {
      return mid;
    }
  }
}

运行结果：

/**
 * 非递归实现数组的折半查找
 */
public class TestBinarySearch {
  public static void main(String[] args) {
    int[] array = {1,2,3,4,5,6,7};
    int key = 7;
    int index = binarySearch(array,key);
    System.out.println(key+"的索引是"+index);
  }
  public static int binarySearch(int[] arr,int key){
    /**
     * 定义起始位置和结束位置索引号，第一次查找从两头开始（即start和end）
     */
    int start = 0;
    int end = arr.length - 1;
    //System.out.println("-1 代表要查的元素不在此数组中");
    while (start <= end){
      /**
       * 计算中间索引号,得到对应元素值
       */
      int mid = (start + end) / 2;
      int value = arr[mid];
      /**
       * 将要查找的元素key值和中间元素比较
       */
      if (key == value){
        return mid;
      }else if (key < value){
        end = mid - 1;
      }else {
        start = mid + 1;
      }
    }
    return -1;
  }
}

运行结果：