求助,在下萌新,arraylist遇到一些问题
恭喜WE 2019-03-12 04:13:17 我先写了一个类:
package pickone_com;
public class Student {
private String name;
private String age;
public Student() {
}
public Student(String name, String age) {
this.name = name;
this.age = age;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getAge() {
return age;
}
public void setAge(String age) {
this.age = age;
}
}
然后写了一个测试类:
package pickone_com;
import java.util.ArrayList;
import java.util.Scanner;
public class StudentDemo {
public static void main(String[] args) {
ArrayList<Student> array = new ArrayList<>();
addStudent(array);
for(int index=0;index<array.size();index++) {
Student s = array.get(index);
System.out.println(s.getName()+" "+s.getAge());
}
}
public static void addStudent(ArrayList<Student> array) {
Scanner sc = new Scanner(System.in);
System.out.print("请输入学生姓名:");
String name = sc.nextLine();
System.out.print("请输入学生姓名:");
String age = sc.nextLine();
Student s = new Student();
s.setName(name);
s.setAge(age);
array.add(s);
}
}
请问:ArrayList<Student> array = new ArrayList<>()里面为什么要写Student啊
public static void addStudent(ArrayList<Student> array){ } 为什么要把这个ArrayList<Student> array传进去啊
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package pickone_com;
import java.util.ArrayList;
public class StudentDemo2 {
public static void main(String[] args) {
ArrayList<ArrayListDomo3> array0 = new ArrayList<>();
Student a1 = new ArrayListDomo3("adjio",23);
Student a2 = new ArrayListDomo3("达摩祖师",99);
Student a3 = new ArrayListDomo3("张三丰",77);
array0.add(a1);
array0.add(a2);
array0.add(a3);
}
}
请问,Student a1 = new ArrayListDomo3("adjio",23)是在调用构造方法吗?为什么要调用这个构造方法啊,不应该写成这个Student s = new Student()的样子吗?我就是搞不明白,Student a1 = new ArrayListDomo3("adjio",23)到底是什么东西,为什么能这样写
为什么上面那个测试类里写的是这个Student s = new Student(),最后这个类里面不这样写啊
构造方法到底是干嘛用的啊