Question

我在java中有一个数组列表，我可能需要输入一个代码来打印名为Artan的行，另一个是打印平均年龄。代码是这样的：

public class Student 
{
    public int nr;
    public String name;
    public int age;
    public String sex;
    public int tall;
    public int weight;
        Student(int nr, String name, int age, String sex, int tall, int weight) {

    this.nr = nr;
    this.name = name;
    this.age = age;
    this.sex = sex;
    this.tall = tall;
    this.weight = weight;
        }
    public static void main (String[] args)
        {
        Student[] arr;
        arr = new Student[10];
        arr[0] = new Student (1, "Artan", 19, "M", 175, 74);
        arr[1] = new Student (2, "Ertan", 30, "M", 179, 80);
        arr[2] = new Student (3, "Jin", 25, "M", 175, 75);
        arr[3] = new Student (4, "Isabella", 28, "F", 165, 54);
        arr[4] = new Student (5, "Anita", 21, "F", 164, 53);
        arr[5] = new Student (6, "Daniel", 32, "M", 180, 82);
        arr[6] = new Student (7, "Anton", 32, "M", 178, 75);
        arr[7] = new Student (8, "Miroslav", 40, "M", 186, 83);
        arr[8] = new Student (9, "Michael", 50, "M", 190, 95);
        arr[9] = new Student (10, "Katarina", 62, "F", 160, 74);

        for (int i = 0; i <= arr.length; i++)
            System.out.println("Student List: "+ arr[i].nr+ " " + arr[i].name+" "+ arr[i].age +" "+ arr[i].sex+" "+ arr[i].tall+"cm  "+ arr[i].weight+"kg");
    }


    }

我应该知道什么，写什么代码？

Answer 1

我会@Override toString()

@Override
public String toString() {
    return "Student{" + "nr=" + nr + ", name=" + name + ", age=" + age + ", sex=" + sex + ", tall=" + tall + ", weight=" + weight + '}';
}

并使用Streams：

Stream.of(arr)
        .filter(x -> x.name.equals("Artan"))
        .forEach(System.out::println);

并计算所有学生的平均年龄：

Double avg = Stream.of(arr)
        .mapToDouble(x -> x.age)
        .average()
        .getAsDouble();
System.out.println(String.format("Average: %s", avg));

Answer 2

for (int i = 0; i < arr.length; i++){
  if (arr[i].name.equals("Artan")){
    System.out.println("Student List: "+ arr[i].nr+ " " + arr[i].name+" "+ arr[i].age +" "+ arr[i].sex+" "+ arr[i].tall+"cm  "+ arr[i].weight+"kg");
  } 
}

您还可以覆盖toString方法并打印出学生对象：

System.out.println("Student : " + arr[i]);

仅打印一个数组列表和平均值

2 个答案: