Question

我一直在尝试通过阅读“Java如何编写早期对象”来了解如何从同一个类的另一个方法内部调用方法。

我现在完全迷失了，书中使用的类比可以很容易地看到正在发生的事情。但是，将其转换为代码具有挑战性。

我已多次尝试解决这个问题并且已经做到了这一点： P.S。 为了简单起见，我排除了我认为对我的问题不重要的代码......

import java.util.Scanner;

public class BuyAHouseInc
{
    private int housePrice;
    private int amountOfHouses;
    private int houseCounter;

    // method to enter the amount of houses on sale
    public void setAmountOfHouses()
    {
        // do stuff etc.
    }

    // method that sets the house price
    public void setHousePrice()
    {
        // do stuff etc.

        calculateFees(this.housePrice); // this is where I'm not sure...
    }

    //method to calculate fees and taxes
    public void calculateFees(int housePrice) // does this receive this.housePrice?
    {
      // do some stuff
    }

测试人员代码：

public class BuyAHouseIncTester
{
    public static void main(String[] args)
    {
        BuyAHouseInc client1 = new BuyAHouseInc("John","Doyle","15 Newton Drive\nDublin 5\n", 550000) // Create object 
        // set amount of houses on sale to client 1
        client1.setAmountOfHouses(); 

        // set house price for each of the houses added to database
        client1.setHousePrice();
    }
}

在另一个方法中调用方法的代码是什么？是否会调用每个房价的价值？

Answer 1

您可以简单地致电calculateFees(housePrice);，因为在通话时可见的唯一housePrice变量为instance variable private int housePrice;

假设您根据创建constructor

的方式进行housePrice来设置BuyAHouseInc

//计算费用和税收的方法 public void calculateFees（int housePrice）//这会收到this.housePrice吗？ { //做一些事情 }

是的，这将通过housePrice

传递calculateFees(housePrice);

calculateFees(int housePrice) 上面定义的局部变量仅在calculateFees(int housePrice){...}方法

中可见

Passing Information to a Method or a Constructor

更新：根据评论，您需要更新您的setter以传递房价

public void setHousePrice(int housePrice)
    {
        this.housePrice = housePrice;

        calculateFees(this.housePrice); 
    }

Answer 2

是的，您的假设是正确的。

然而，有一些重要的事项需要注意。这段代码：

react-rails

Java是按值传递的。您已经传递了housePrice的值，但您没有修改原来的housePrice。

所以如果你做某些事情＆＃34;并修改传入的housePrice变量，除非您在calculateFees中设置housePrice，否则不会保存这些更改。

在这种情况下，最好通过getter / setter操纵任何成员变量。顺便说一下，惯例是，设定者应该总是取值。这并不是随意的，因为许多库依赖于以某种方式起作用的set / get方法。

我已经对上述答案进行了更清晰的编辑。

Answer 3

如果我错了，请纠正我，但这是一个可能的解决方案：

public void setHousePrice(int price)
{


    calculateFees(price); 
}


public void calculateFees(int housePrice) 
{
  // stuff with housePrice
}

然后做

variable.setHousePrice(variable.getHousePrice);

Answer 4

public class BuyAHouseInc {
    private double housePrice;
    private int amountOfHouses;
    private int houseCounter;

    public BuyAHouseInc(double housePrice, int amountOfHouses, int houseCounter) {
        this.housePrice = housePrice;
        this.amountOfHouses = amountOfHouses;
        this.houseCounter = houseCounter;
    }

    // method that sets the house price
    public void generateHousePrice() {
        // do stuff etc.
        // you could also put the logic in the set method... Had to change the method name to 
        // generate as the getters and setter where created and the setter method is named
        // exactly like your previous method
        calculateFees(housePrice); // this is were I'm not sure...
    }

    // method to calculate fees and taxes
    public void calculateFees(double housePrice) // does this receive
                                                    // this.housePrice?
    {
        // do some stuff
    }

    public double getHousePrice() {
        return housePrice;
    }

    public void setHousePrice(double housePrice) {
        this.housePrice = housePrice;
    }

    public int getAmountOfHouses() {
        return amountOfHouses;
    }

    public void setAmountOfHouses(int amountOfHouses) {
        this.amountOfHouses = amountOfHouses;
    }

    public int getHouseCounter() {
        return houseCounter;
    }

    public void setHouseCounter(int houseCounter) {
        this.houseCounter = houseCounter;
    }

    @Override
    public String toString() {
    return "BuyAHouseInc [housePrice=" + housePrice + ", amountOfHouses=" + amountOfHouses + ", houseCounter="
            + houseCounter + "]";
}


}

将两个类分隔在不同的文件中。另一件需要指出的是使用double代替int而不是int。您还必须创建getter和setter才能获取和设置属性。您还必须在类中添加构造函数。然后，您可以在main中创建该类的实例并调用其方法。主要方法如下所示。

public class Main {

    public static void main(String... args) {
        BuyAHouseInc test = new BuyAHouseInc(200000, 4, 2);
        test.setAmountOfHouses(6); // changed from 4 to 6
        test.generateHousePrice();
        test.calculateFees(test.getHousePrice());
        test.toString();

    }
}

希望你觉得这很有帮助，祝你好运！我编辑了代码并添加了toString方法以将信息输出为字符串。

如何从同一个类中的另一个方法调用方法（java）

4 个答案: