[英]How to return an anonymous instantiated object in java
在步驟4中,我必須使用輸入的4個信息項返回匿名實例化的Student對象。 由於找不到任何解決此問題的論壇,因此我需要一些幫助來設置它或示例。
import java.util.Scanner;
public class Students
{
private static Scanner input = new Scanner(System.in);
public static void main(String[] args)
{
Student[] students;
students = getStudents();
printStudents(students);
}
private static Student[] getStudents()
{
Student[] temp;
int how_many;
System.out.print("How many students? ");
how_many = input.nextInt();
purgeInputBuffer();
temp = new Student[input.nextInt()]; // Step 1
for (int i = 0; i < temp.length; i++)
{
getStudent();
temp[i] = getStudent(); // Step 2
}
return temp; // Step 3
}
private static Student getStudent()
{
String name,
address,
major;
double gpa;
System.out.print("Enter name: ");
name = input.nextLine();
System.out.print("Enter address: ");
address = input.nextLine();
System.out.print("Enter major: ");
major = input.nextLine();
System.out.print("Enter GPA: ");
gpa = input.nextDouble();
purgeInputBuffer();
return ___________________________________________________; // Step 4
}
private static void printStudents(Student[] s)
{
System.out.println();
for (int i = 0; i < s.length; i++) // Step 5
{
System.out.println(______); // Step 6
}
}
private static void purgeInputBuffer()
{
// ----------------------------------------------------
// Purge input buffer by reading and ignoring remaining
// characters in input buffer including the newline
// ----------------------------------------------------
input.nextLine();
}
}
只是
return new Student(constructor args);
constructor args
是Student
構造函數需要的任何參數。
這里使用“匿名”不是標准的Java術語。 我想因為您沒有將對象引用分配給局部變量,所以可以將其視為“匿名”。 由於在以下位置的getStudent()
中調用了getStudents()
,因此它不會長時間保持匿名狀態
temp[i] = getStudent();
因此引用將立即保存(到數組中)。
“匿名”出現在術語“匿名子類”中,但這是您可能尚未涉及的完全不同的概念。
您可以將字段設為私有,並使用參數化的構造函數對其進行初始化。
public class Students
{
private static Scanner input = new Scanner(System.in);
private String name;
private String address;
private String major;
double gpa;
public Students(String name, String address, String major, double gpa) {
this.name = name;
this.address = address;
this.gpa = gpa;
this.major = major;
}
public static void main(String[] args)
{
Student[] students;
students = getStudents();
printStudents(students);
}
private static Student[] getStudents()
{
Student[] temp;
int how_many;
System.out.print("How many students? ");
how_many = input.nextInt();
purgeInputBuffer();
temp = new Student[input.nextInt()]; // Step 1
for (int i = 0; i < temp.length; i++)
{
getStudent();
temp[i] = getStudent(); // Step 2
}
return temp; // Step 3
}
private static Student getStudent()
{
String name,
address,
major;
double gpa;
System.out.print("Enter name: ");
name = input.nextLine();
System.out.print("Enter address: ");
address = input.nextLine();
System.out.print("Enter major: ");
major = input.nextLine();
System.out.print("Enter GPA: ");
gpa = input.nextDouble();
purgeInputBuffer();
return new Students(name,address,major,gpa); // Step 4
}
private static void printStudents(Student[] s)
{
System.out.println();
for (int i = 0; i < s.length; i++) // Step 5
{
System.out.println(______); // Step 6
}
}
private static void purgeInputBuffer()
{
// ----------------------------------------------------
// Purge input buffer by reading and ignoring remaining
// characters in input buffer including the newline
// ----------------------------------------------------
input.nextLine();
}
}
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