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[英]How to access the variables of a function of a class from another class in Java
[英]How to access variables in another class, Java?
我有多个相同的 package 类,需要访问不同类中的一些变量。 如何从 Car class 中的 MenuDisplay 访问 carName? 感觉就像我快到了,但就是想不通。 谢谢
package carrentaltester;
import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;
public class MenuDisplay {
public static void displayCarList() {
String CSVfileName = "CarList.csv";
int counter = 0;
try { //open and read the CSV file
File file = new File(CSVfileName);
Scanner input = new Scanner(file);
System.out.format("%-8s%-18s%-10s%-16s%-16s%-16s\n",
"Car No.", "Car Name", "Seats", "Transmission", "Car Type",
"Rate/Day($");
System.out.format("%-8s%-18s%-10s%-16s%-16s%-16s\n", "-------",
"-------", "----- ", "------------", "---------",
"--------");
while (input.hasNextLine()) {
String line = input.nextLine();
counter++;
String fields[] = line.split(",");
String carNumber = fields[0];
String carName = fields[1];
String seats = fields[2];
String transmission = fields[3];
String carType = fields[4];
String ratePerDay = fields[5];
System.out.format("%-8s%-18s%-10s%-16s%-16s%-16s\n",
carNumber, carName, seats, transmission, carType,
ratePerDay);
}
package carrentaltester;
public class Car {
double carRate;
String carName;
MenuDisplay carInfo = new MenuDisplay();
}
carName
是Car
object 的字段变量。 您必须首先实例化一个Car
,然后访问它的carName
字段。
Car car = new Car();
(...)
car.carName = fields[1];
您应该在哪里实例化Car
object 取决于具体情况。 我会将它作为参数传递给displayCarList
。
public static void displayCarList(Car car) {
(...)
car.carName = fields[1];
(...)
}
用法:
public class Car {
double carRate;
String carName;
public static void main(String[] args) {
Car car = new Car();
MenuDisplay carInfo = new MenuDisplay(car);
}
}
创建汽车 class 的 object 并设置值。 然后就可以访问了。
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