Java-泛型实验

Posted 2022-12-14 康小庄

1.定义一个学生类Student，具有年龄age和姓名name两个属性，并通过实现Comparable接口提供比较规则（返回两个学生的年龄差）， 定义测试类Test，在测试类中定义测试方法Comparable getMax(Comparable c1, Comparable c2)完成测试

Student

public class Student implements Comparable<Student> 

	private String name;
	private int age;

	public Student() 
		super();
	

	public Student(String name, int age) 
		super();
		this.name = name;
		this.age = age;
	

	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;
	

	@Override
	public String toString() 
		return "Student [name=" + name + ", age=" + age + "]";
	

	@Override
	public int compareTo(Student s) 
		Student student = (Student) s;

		return this.getAge() - student.getAge();
	

StudentTest

public class StudentTest 

	public static void main(String[] args) 
		Student s1 = new Student("张三", 18);

		Student s2 = new Student("李四", 30);

		if (getMax(s1, s2) < 0) 
			System.out.println("年龄大的是->" + s2);
		 else 
			System.out.println("年龄大的是->" + s1);
		
	

	public static int getMax(Comparable<Student> c1, Comparable<Student> c2) 
		return c1.compareTo((Student) c2);
	

2.模拟ArrayList集合自定义一个集合类MyArrayList，完成添加和删除功能的泛型设计，定义测试类完成测试

MyArrayList

public class MyArrayList<E> 

	// 默认大小
	private static final int DEFAULT_CAPACITY = 10;
	// 找不到值为-1
	public static final int ELEMENT_NOT_FOUND = -1;
	// 集合大小
	private int size;
	// 存放元素的数组
	private E[] elements;

	// 构造方法
	public MyArrayList() 
		clear();
	

	/**
	 * 
	 * @Title: clear
	 * @Description: 清空集合
	 * @param:
	 * @author: KangXiaoZhuang
	 * @email: [e-mail]
	 */
	public void clear() 
		size = 0;
		ensureCapacity(DEFAULT_CAPACITY);
	

	/**
	 * 
	 * @Title: ensureCapacity
	 * @Description: 开辟一个新的数组，扩容操作
	 * @param: @param newCapacity
	 * @author: KangXiaoZhuang
	 * @email: [e-mail]
	 */
	@SuppressWarnings("unchecked")
	public void ensureCapacity(int newCapacity) 
		if (newCapacity < size) 
			return;
		
		E[] oldElements = elements;
		// 新建一个数组
		elements = (E[]) new Object[newCapacity];
		for (int i = 0; i < size; i++) 
			elements[i] = oldElements[i];
		
	

	/**
	 * 
	 * @Title: size
	 * @Description: 返回集合大小
	 * @param: @return
	 * @author: KangXiaoZhuang
	 * @email: [e-mail]
	 */
	public int size() 
		return size;
	

	/**
	 * 
	 * @Title: isEmpty
	 * @Description: 返回集合是否为空
	 * @param: @return
	 * @author: KangXiaoZhuang
	 * @email: [e-mail]
	 */
	public boolean isEmpty() 
		return size() == 0;
	

	/**
	 * 
	 * @Title: trimToSize
	 * @Description: 修改指定大小
	 * @param:
	 * @author: KangXiaoZhuang
	 * @email: [e-mail]
	 */
	public void trimToSize() 
		ensureCapacity(size());
	

	/**
	 * 
	 * @Title: get
	 * @Description: 获取指定索引的元素
	 * @param: @param  index
	 * @param: @return
	 * @author: KangXiaoZhuang
	 * @email: [e-mail]
	 */
	public E get(int index) 
		rangeCheck(index);
		return elements[index];
	

	/**
	 * 
	 * @Title: indexOf
	 * @Description: 查看元素的索引
	 * @param: @param  element
	 * @param: @return
	 * @author: KangXiaoZhuang
	 * @email: [e-mail]
	 */
	public int indexOf(E element) 
		if (element == null) 
			for (int i = 0; i < size; i++) 
				if (elements[i] == null)
					return i;
			
		 else 
			for (int i = 0; i < size; i++) 
				if (element.equals(elements[i]))
					return i;
			
		
		return ELEMENT_NOT_FOUND;
	

	/**
	 * 
	 * @Title: contains
	 * @Description: 是否包含指定元素
	 * @param: @param  element
	 * @param: @return
	 * @author: KangXiaoZhuang
	 * @email: [e-mail]
	 */
	public boolean contains(E element) 
		return indexOf(element) != ELEMENT_NOT_FOUND;
	

	/**
	 * 
	 * @Title: set
	 * @Description: 修改指定索引的值
	 * @param: @param  index
	 * @param: @param  newElement
	 * @param: @return
	 * @author: KangXiaoZhuang
	 * @email: [e-mail]
	 */
	public E set(int index, E newElement) 
		rangeCheck(index);
		E old = elements[index];
		elements[index] = newElement;
		return old;
	

	/**
	 * 
	 * @Title: add
	 * @Description: 直接从尾部插入
	 * @param: @param  addElement 添加的元素
	 * @param: @return
	 * @author: KangXiaoZhuang
	 * @email: [e-mail]
	 */
	public boolean add(E addElement) 
		add(size(), addElement);
		return true;
	

	/**
	 * 
	 * @Title: add
	 * @Description: 指定索引位置添加元素
	 * @param: @param index 索引
	 * @param: @param addElement 添加的元素
	 * @author: KangXiaoZhuang
	 * @email: [e-mail]
	 */
	public void add(int index, E addElement) 
		// 先判断是否需要扩容
		if (elements.length == size()) 
			ensureCapacity(size() * 2 + 1);
		
		// 集合元素往后移动
		for (int i = size; i > index; i--) 
			elements[i] = elements[i - 1];
		
		elements[index] = addElement;
		size++;
	

	/**
	 * 
	 * @Title: remove
	 * @Description: 删除指定索引的元素
	 * @param: @param  index
	 * @param: @return
	 * @author: KangXiaoZhuang
	 * @email: [e-mail]
	 */
	public E remove(int index) 
		E removeElement = elements[index];
		// 集合的元素统一向前移动
		for (int i = index; i < size() - 1; i++) 
			elements[i] = elements[i + 1];
		
		// 长度减1
		size--;

		return removeElement;
	

	/**
	 * 
	 * @Title: rangeCheck
	 * @Description: 判断索引是否合法
	 * @param: @param index
	 * @author: KangXiaoZhuang
	 * @email: [e-mail]
	 */
	public void rangeCheck(int index) 
		if (index < 0 || index >= size()) 
			throw new ArrayIndexOutOfBoundsException("索引越界异常!!!");
		
	

	public void print() 
		for (int i = 0; i < size; i++) 
			System.out.print(elements[i] + " ");
		
		System.out.println();
	

MyArrayListTest

public class MyArrayListTest 
	public static void main(String[] args) 
		MyArrayList<Integer> list = new MyArrayList<>();
		list.add(getRandom());
		list.add(getRandom());
		list.add(getRandom());
		list.add(getRandom());
		list.add(getRandom());
		list.print();

		System.out.println("==========删除操作==========");
		list.remove(2);
		list.print();
	

	public static int getRandom() 
		Random random = new Random();
		return random.nextInt(10);
	

3.定义一个泛型方法printArray，可以打印输出任何类型的数组，例如：[“小明”,”小红”,”小兰”]，[1,2,3] ，定义测试类完成测试。

public class PrintArray 
	public static void main(String[] args) 
		Integer[] intArray =  1, 2, 3, 4, 5 ;
		Double[] doubleArray =  1.1, 2.2, 3.3, 4.4 ;
		Character[] charArray =  'H', 'E', 'L', 'L', 'O' ;
		String[] stringArray =  "小明", "小红", "小兰" ;
		System.out.println("整型数组元素为:");
		printArray(intArray);
		System.out.println("\\n双精度型数组元素为:");
		printArray(doubleArray);
		System.out.println("\\n字符型数组元素为:");
		printArray(charArray);
		System.out.println("\\n字符串数组元素为:");
		printArray(stringArray);
	

	public static <T> void printArray(T[] array) 
		System.out.println(Arrays.toString(array));
	

4.为某系统提供一个泛型接口Data,该接口可以约束非泛型类TeacherData和StudentData必须完成数据（学生、老师）的增删改查操作

Data

public interface Data<T> 

	void add(T t);

	void remove(T t);

	void update(int index, T t);

	T query(int index);

Student

public class Student 
	private int id;
	private String name;

	public Student(int id, String name) 
		super();
		this.id = id;
		this.name = name;
	

	public Student() 
		super();
	

	public int getId() 
		return id;
	

	public void setId(int id) 
		this.id = id;
	

	public String getName() 
		return name;
	

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

	@Override
	public String toString() 
		return "Student [id=" + id + ", name=" + name + "]";
	

StudentData

public class StudentData implements Data<Student> 

	ArrayList<Student> studentList = new ArrayList<>();

	@Override
	public void add(Student s) 
		studentList.add(s);
	

	@Override
	public void remove(Student s) 
		studentList.remove(s);
	

	@Override
	public void update(int index, Student s) 
		for (int i = 0; i < studentList.size(); i++) 
			if (s == studentList.get(i)) 
				index = i;
				break;
			
		
		studentList.set(index, s);
	

	@Override
	public Student query(int index) 
		return studentList.get(index);
	

	public ArrayList<Student> getArrayList() 
		return this.studentList;
	

TeacherData

public class TeacherData implements Data<Teacher> 

	ArrayList<Teacher> teacherList = new ArrayList<>();

	@Override
	public void add(Teacher t) 
		teacherList.add(t);
	

	@Override
	public void remove(Teacher t) 
		teacherList.remove(t);
	

	@Override
	public void update(int index, Teacher t) 
		for (int i = 0; i < teacherList.size(); i++) 
			if (t == teacherList.get(i)) 
				index = i;
				break;
			
		
		teacherList.set(index, t);
	

	@Override
	public Teacher query(int index) 
		return teacherList.get(index);
	

	public ArrayList<Teacher> getArrayList() 
		return this.teacherList;
	

DataTest

public class DataTest 

	public static void main(String[] args) 
		DataTest dataTest = new DataTest();
		dataTest.testStudent();
		System.out.println("
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