基于数组的一个简单增删改查

1、实现功能：

• 基于数组实现，数组长度由用户输入，数组会进行动态扩充

• 扩充原理：扩充长度为原数组长度的2倍

• 可进行添加、修改、删除、查询操作。

2、代码实现

2.1、Chicken.java

public class Chicken {
    private int id;
    private String name;
    private int age;

    public Chicken() {
        
    }
    public Chicken(int id, String name, int age) {
        this.id = id;
        this.name = name;
        this.age = age;
    }
    // get,set
}    

2.2、ChickenManager.java

public class ChickenManager {
    private static int count = 0;//用来判断数组中有几个对象
    private Chicken[] chickens; // 数组对象

    // 如果用户输入小于0，则默认数组长度为5
    public ChickenManager(int size) {
        if (size > 0) {
            chickens = new Chicken[size];
        } else {
            chickens = new Chicken[5];
        }
    }

    /**
     * 获取数组的长度
     */
    public int getLength() {
        return chickens.length;
    }
	// 添加方法
    public void add(Chicken... chicken) {
        for (Chicken c : chicken
        ) {
            if (count >= chickens.length) {
                // 需要扩充数组(扩充一半 *3/2+1，扩充一倍*2)
                //  chickens = Arrays.copyOf(chickens,chickens.length*2);
                Chicken[] chickens1 = new Chicken[chickens.length * 2];
                System.arraycopy(chickens, 0, chickens1, 0, chickens.length);
                chickens = chickens1;
            }
            chickens[count] = c;
            count++;
        }
    }
	// 删除方法
    public void delete(int id) {
        for (int i = 0; i < count; i++) {
            if (chickens[i].getId() == id) {
                // 删除后，后面所有元素需要向前移动
                if (count - 1 - i >= 0) {
                    System.arraycopy(chickens, i + 1, chickens, i, count - 1 - i);
                }
                chickens[count - 1] = null;
                count--;
                break;
            }
        }
    }
    // 修改
    public void update(Chicken chicken) {
        Chicken chicken1 = selectById(chicken.getId());
        if (chicken1 != null) {
            chicken1.setAge(chicken.getAge());
            chicken1.setName(chicken.getName());
        }
    }
	// 查询
    public void select() {
        System.out.println(Arrays.toString(chickens));
    }
	// 根据id查询
    public Chicken selectById(int id) {
        for (int i = 0; i < count; i++) {
            if (chickens[i].getId() == id) {
                return chickens[i];
            }
        }
        return null;
    }

}

3、测试

public class Test8 {
    public static void main(String[] args) {
        // 默认数组长度为1
        ChickenManager chickenManager = new ChickenManager(1);
        // 添加，数组会动态扩充
        chickenManager.add(new Chicken(1, "花花", 12), new Chicken(2, "詹三", 23), new Chicken(3, "嘿嘿", 12), new Chicken(4, "丽丽", 32), new Chicken(5, "杨洋", 23));
        // 增删改查操作
    }
}