java玩转数据结构02 数组中 使用泛型

 

public class Array<TypeE> {

    private TypeE[] data;
    private int size;


    //有参构造函数
    public Array(int capacity)
    {
        data = (TypeE[]) new Object[capacity];
        size = 0;
    }
    //无参构造函数
    public Array(){
        this(10);
        System.out.println("Here");
    }

//    获取index索引位置的元素
    TypeE get(int index)
    {
        if(index < 0 || index >= size)
            throw new IllegalArgumentException("Get failed, Index is illegal");
        return data[index];
    }

    //修改index索引位置的元素为e
    void set(int index, TypeE e){
        if(index < 0 || index >= size)
            throw new IllegalArgumentException("Get failed, Index is illegal");
        data[index] = e;
    }

    public int getSize(){
        return size;
    }

    public int getCapacity(){
        return data.length;
    }

    public boolean isEmpty(){
        return size == 0;
    }

    public void addLast(TypeE e){

        add(size, e);
    }

    public void addFirst(TypeE e)
    {
        add(0, e);
    }

    public void add(int index, TypeE e){
        if (size == data.length)
        {
            throw new IllegalArgumentException("addlast failed, array is full.");
        }

        if (index < 0 || index > size){
            throw new IllegalArgumentException("add failed,Require index < 0 || index > size.");
        }

        for (int i = size - 1; i >= index; i--){
            data[i + 1] = data [i];
        }
        data[index] = e;
        size ++;
    }

    //包含
    public boolean contains(TypeE e){
        for (int i = 0; i < size; i++) {
            if( data[i].equals(e))//引用比较
                return  true;
        }
        return false;
    }
    //查找数组中元素e所在的索引如果不存在元素e,则-1
    public  int find(TypeE e){
        for (int i = 0; i < size; i++) {
            if( data[i].equals(e))//引用比较
                return  i;
        }
        return -1;

    }
    //删除元素,返回删除的元素
    public TypeE remove(int index){
        if(index < 0 || index >= size)
            throw new IllegalArgumentException("Get failed, Index is illegal");
        TypeE retValue = data[index];
        for (int i = index + 1; i < size; i++) {
            data[i-1] = data[i];
        }
        size --;
        data[size] = null;//不是必须的 loitering objects != memory leak
        return retValue;
    }

    public TypeE removeFirst()
    {
       return remove(0);
    }

    public TypeE removeLast(){
        return remove(size - 1);
    }

    public void removeElement(TypeE e)
    {
        int index = find(e);
        if(index != -1)
            remove(index);
    }


    @Override
    public String toString(){
        StringBuilder res = new StringBuilder();
        res.append(String.format("Array: size = %d, capacity = %d\n", size, data.length));
        res.append('[');
        for (int i = 0; i < size; i++)
        {
            res.append(data[i]);
            if( i != size -1)
                res.append(", ");
        }
        res.append(']');
        return res.toString();
    }

}

public class Main {
    public static void main(String[] args) {
        Array<Integer> arr = new Array<>(20);

        for (int i = 0; i < 10; i++) {
            arr.addLast(i);
        }

        System.out.println(arr);

        arr.add(1, 100);
        System.out.println(arr);

        arr.addFirst(-1);
        System.out.println(arr.getSize());
        System.out.println(arr.toString());


        arr.remove(2);
        System.out.println(arr);

        arr.removeElement(4);
        System.out.println(arr);

        arr.removeFirst();
        System.out.println(arr);

        arr.removeLast();
        System.out.println(arr);
    }
}

public class Student {

    private String name;
    private int score;

    public Student(String stuName, int stuScore){
        name = stuName;
        score = stuScore;
    }

    @Override
    public String toString(){
        return String.format("Student(name: %s, score: %d)", name, score);
    }

    public static void  main(String[] args)
    {
        Array<Student> arr = new Array<>();
        arr.addLast(new Student("alice", 100));
        arr.addLast(new Student("Michael", 88));

        System.out.println(arr);

    }

}