我有一堂课说
Students registeredStudent = null;
由于没有上课，我必须自己写学生课。我似乎无法弄清楚“学生”类中的registeredStudent价值。目前，我的学生课程如下-
public class Students {
String name;
String id;
//boolean selectedStudent;
public Students(String id, String name){
this.id = id;
this.name = name;
}
public void display(){
System.out.println("ID : " + id);
System.out.println("Name of Student :" + name);
}
}
公共类DrivingSchool {
private Autocar [] ac = new Autocar[10];
private Motorbike [] m = new Motorbike[10];
private Manualcar [] mc = new Manualcar[10];
private Students [] s = new Students[30];
public void start(){
String[]menu = {"Display all vehicles", "Display all students",
"Register a new student", "Assign student an auto car", "Assign student a manual car",
"Assign student a motorbike","Deregister a student"};
while(true){
int choice = Keyboard.readInt("Enter Your Choice >");
if(choice == 1){
displayAllV();
}
else if(choice == 2){
}
else if(choice == 3){
}
else if(choice == 4){
}
else if(choice == 5){
}
else if(choice == 6){
}
else if(choice == 7){
}
else{
break;
}
}
}
public void displayAllV(){
for(int i = 0;i < ac.length; i++){
if(ac[i] != null){
ac[i].display();
}
}
for(int j = 0; j<m.length; j++){
if(m[j] != null){
m[j].display();
}
}
for(int x = 0; x < mc.length; x++){
if(mc[x]!=null){
mc[x].display();
}
}
}
public void displayAllStud(){
boolean hasStud = false;
for(int i = 0;i < s.length; i++){
if(s[i] != null){
s[i].display();
hasStud = true;
}
}
if(!hasStud){
System.out.println("No Student Registered");
}
}
public void registerStud(){
String id = Keyboard.readString("Enter Student ID :");
for(int i = 0;i < s.length; i++){
if(s[i]!= null && id.equals(s[i].id)){
System.out.println("Student with this ID already exist");
return;
}
}
boolean registered = false;
for(int i =0;i < s.length; i++){
if(s[i] == null){
String name = Keyboard.readString("Enter Student name :");
s[i] = new Students(id, name);
System.out.println("A new student is registered.");
registered = true;
break;
}
}
if(!registered){
System.out.println("Unable to register. School is full");
}
}
public void assignAutoCar(){
String id = Keyboard.readString("Enter Student ID :");
Students selectedStudent = null;
for(int i =0; i<s.length; i++){
if(s[i] != null && id.equals(s[i].id)){
selectedStudent = s[i];
break;
}
}
if(selectedStudent != null && selectedStudent.autocar == null){
for(int i =0; i < ac.length; i++){
if(ac[i].isVehicleAvailable()){
ac[i].setAvail(false);
selectedStudent.autoCar = ac[i];
break;
}
}
public void createVehicles(){
ac[0] = new Autocar("LA1", 4);
ac[1] = new Autocar("LA2", 4);
ac[2] = new Autocar("LA3", 4);
ac[3] = new Autocar("LA4", 4);
ac[4] = new Autocar("LA5", 4);
mc[0] = new Manualcar("LM1", 4, 5);
mc[1] = new Manualcar("LM2", 4, 5);
mc[2] = new Manualcar("LM3", 4, 5);
mc[3] = new Manualcar("LM4", 4, 5);
mc[4] = new Manualcar("LM5", 4, 5);
m[0] = new Motorbike("M1", 2);
m[1] = new Motorbike("M2", 2);
m[2] = new Motorbike("M3", 3);
m[3] = new Motorbike("M4", 3);
m[4] = new Motorbike("M5", 4);
}
}
最佳答案
好的，首先，registeredStudent不是您的Student类的一部分。
此作业：
Students registeredStudent = null;
这是主要方法中的内容：嘿，我希望registeredStudent是一个局部变量，它是对Student类型（您的班级）对象的引用，当前使其指向null。
您可以使用以下方法将registeredStudent指向实际的Student对象：
registeredStudent = new Students("1", "Mike");
因此，现在，registeredStudent指向一个新的Student对象，该对象的ID为1，名称为Mike。
因此，registeredStudent不属于Student类。它只是main方法中的局部变量。
（注意：最好以单数形式命名课程：例如，学生而不是学生。当您要创建新的学生对象时，新学生（...）比新学生（...）更有意义