如何通过Java中的参数传递变量？

Question

我正在学习Java，并且我已经完成了用Java编写邮资系统的任务。继承我的任务：

“实现方法public booelan updateTrackingHistory（String datetime，String location），它可以更新Parcel在从发件人传输到收件人时的跟踪历史记录，如下所示。 如果尚未为包裹设置书包尺寸，或者已经交付包裹，则该方法应立即返回false。 否则，该方法应构建一个新的跟踪条目，记录日期/时间和位置，之后新的跟踪条目应附加到新行的跟踪历史记录中。 跟踪历史记录更新后，该方法应返回true，表示跟踪更新已成功记录。“

这是我到目前为止编写的所有代码，但我有点困在构建新的跟踪条目而不确定如何继续这种方法。这段代码中的最后一个方法是我卡住了。

public class parcel {

//Instance Variables
//The info we need to keep track of
private String parcelNumber;
private String senderName;
private String returnAddress;
private String recipientName;
private String deliveryAddress;
private String contactNumber;
private String satchelSize;
private boolean deliveryComplete;
private String trackingHistory;

//Constructors

public parcel (String parcelNumber, String senderName, String returnAddress, String recipientName, 
        String deliveryAddress, String contactNumber, String trackingHistory) {

    this.parcelNumber = parcelNumber;
    this.senderName = senderName;
    this.returnAddress = returnAddress;
    this.recipientName = recipientName;
    this.deliveryAddress = deliveryAddress;
    this.contactNumber = contactNumber;
    this.trackingHistory = "";

}

//Getters
public String getparcelNumber() {

    return parcelNumber;
}

public String getrecipientName() {

    return recipientName;
}

public String getdeliveryAddress() {

    return deliveryAddress;
}

public String getcontactNumber() {

    return contactNumber;
}

//Helper Method.
public int calculatePostageCost() {
    int postCost = 0;
    int trackingFee = 5;

    if(satchelSize.equals("Small") || satchelSize.equals("small")) 
        postCost = trackingFee + 10;

    else if(satchelSize.equals("Medium") || satchelSize.equals("medium"))
        postCost = trackingFee + 13;

    else if(satchelSize.equals("Large") || satchelSize.equals("large"))
        postCost = trackingFee + 17;


    return postCost;
}

//Method
public int selectSatchel(int parcelLength, int parcelWidth) {

    if(satchelSize != null) 
        return -1;

    if(parcelLength > 500 || parcelWidth > 400)

        return 0;

    else {

    //code for finding out smallest parcel size it will fit in  
    return calculatePostageCost();

    }
}

public boolean updateTrackingHistory(String datetime, String location ) {

    if(satchelSize == null || satchelSize.isEmpty())
    {
        return false;
    }
    //Check if parcel has already been delivered 
    else if(trackingHistory != null) {

    return false;   

    }


}

Answer 1

好，但我主要担心的是这个方法基于任务：

public boolean updateTrackingHistory(String datetime, String location ) {

if(satchelSize == null || satchelSize.isEmpty())
{
    return false;
}
//Check if parcel has already been delivered 
else if(trackingHistory != null) {

return false;   

}


}