Java学习复杂的对象数组操作

定义一个长度为3的数组，数组存储1~3名学生对象作为初始数据，学生对象的学号，姓名各不相同。
学生的属性：学号，姓名，年龄。

• 要求1：再次添加一个学生对象，并在添加的时候进行学* 号的唯一性判断。
• 要求2：添加完毕之后，遍历所有学生信息。
• 要求3：通过id删除学生信息
  ​ 如果存在，则删除，如果不存在，则提示删除失败。
• 要求4：删除完毕之后，遍历所有学生信息。
• 要求5：查询数组id为“heima002”的学生，如果存在，则将他的年龄+1岁

package test;

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

    public Student(int id, String name, int age) {
        this.id = id;
        this.name = name;
        this.age = age;
    }

    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;
    }

    public int getAge() {
        return age;
    }

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

package test;

public class Test {
    public static void main(String[] args) {
        Student[] a = new Student[3];
        Student stu1 = new Student(1,"zhangsan",23);
        Student stu2 = new Student(2,"lisi",24);
        a[0] = stu1;
        a[1] = stu2;
        Student stu4 = new Student(3,"linda",25);

        boolean flag = contains(a,stu4.getId());
        if(flag){
            System.out.println("当前id值重复，请修改后重试!");
        }else{
            int count = getCount(a);
            if (count == a.length) {
                Student[] newarr = creatNewarr(a);
                newarr[count] = stu4;
                printArr(newarr);
            }else{
                a[count] = stu4;
                printArr(a);
            }
        }

    }
    public static boolean contains(Student[] a,int id){
        for (int i = 0; i < a.length; i++) {
            Student stu = a[i];
            if(stu != null){
                int sid = stu.getId();
                if (sid == id) {
                    return true;
                }
            }

        }
        return false;
    }
    public static  int getCount(Student[] a){
        int count = 0;
        for (int i = 0; i < a.length; i++) {
            if (a[i] != null) {
                count++;
            }
        }
        return  count;
    }
    public static Student[] creatNewarr(Student[] a){
        Student[] newarr = new Student[a.length+1];
        for (int i = 0; i < a.length; i++) {
            newarr[i] = a[i];
        }
        return newarr;
    }
    public static void printArr(Student[] a){
        for (int i = 0; i < a.length; i++) {
            Student stu = a[i];
            if(stu != null){
                System.out.println(stu.getId()+","+stu.getName()+","+stu.getAge());
            }
        }

    }
}

package test;

public class Test1 {
    public static void main(String[] args) {
        Student[] b =new Student[3];
        Student stu1 = new Student(1, "zhangsan", 23);
        Student stu2 = new Student(2, "lisi", 24);
        Student stu3 = new Student(3, "wangwu", 25);

        b[0] = stu1;
        b[1] = stu2;
        b[2] = stu3;
        int index = getId(b,5);
        if( index >= 0){
            b[index] = null;
        }else {
            System.out.println("所删除的id不存在，删除失败！");
        }
    }
    public static void printArr(Student[] arr){
        for (int i = 0; i < arr.length; i++) {
            Student stu = arr[i];
            if(stu != null){
                System.out.println(stu.getId() + ", " + stu.getName() + ", " + stu.getAge());
            }
        }
    }
    public static  int getId(Student[] b,int id){
        for (int i = 0; i < b.length; i++) {
            Student stu = b[i];
            if (stu != null) {
                int sid = stu.getId();
                if (sid == id) {
                    return  i;
                }
            }
        }
        return -1;
    }
}

package test;

public class Test2 {
    public static void main(String[] args) {
        Student[] arr = new Student[3];

        Student stu1 = new Student(1, "zhangsan", 23);
        Student stu2 = new Student(2, "lisi", 24);
        Student stu3 = new Student(3, "wangwu", 25);

        arr[0] = stu1;
        arr[1] = stu2;
        arr[2] = stu3;

        int index = getIndex(arr, 5);
        if(index >= 0){
            //存在， 则将他的年龄+1岁
            Student stu = arr[index];
            //把原来的年龄拿出来
            int newAge = stu.getAge() + 1;
            //把+1之后的年龄塞回去
            stu.setAge(newAge);
            //遍历数组
            printArr(arr);
        }else{
            //不存在，则直接提示
            System.out.println("当前id不存在，修改失败!");
        }

    }
    public static int getIndex(Student[] arr , int id){
        for (int i = 0; i < arr.length; i++) {
            //依次得到每一个学生对象
            Student stu = arr[i];
            //对stu进行一个非空判断
            if(stu != null){
                int sid = stu.getId();
                if(sid == id){
                    return i;
                }
            }
        }

        //当循环结束之后，还没有找到就表示不存在
        return -1;
    }

    public static void printArr(Student[] arr){
        for (int i = 0; i < arr.length; i++) {
            Student stu = arr[i];
            if(stu != null){
                System.out.println(stu.getId() + ", " + stu.getName() + ", " + stu.getAge());
            }
        }
    }
}

今天先记录到这里了！