好的我有多个Java文件，但目前只看2，我正在做一个GUI程序。 我有一个Landlords的arraylist在一个文件中使用getLandlords方法返回数组并且它不会工作eclipse只是给出错误无论我尝试什么 档案1
package assignment2;
import java.awt.event.*;
import java.awt.*;
import java.util.*;
import javax.swing.*;
import javax.swing.event.ListSelectionEvent;
import javax.swing.event.ListSelectionListener;
public class RealEstateManage extends JFrame implements ActionListener, ListSelectionListener{
public static void main(String[] args)
{
RealEstateManage theGUI = new RealEstateManage();
}
//Initial setup for base of GUI
private JFrame jfFrame;
private JButton jbAddLandlord, jbAddProperty, jbAddLease, jbRecord, jbMaintenance, jbDisplayproperty;
private JTextArea jtaResults;
private JTextField jtfinput1, jtfinput2, jtfinput3, jtfinput4;
private JList <Landlord> jlLandlord;
private Vector<Landlord> vlist = new Vector<Landlord>();
private JPanel jpButtons = setupButtons(), jpResults = setupResults();
public RealEstateAgency R = new RealEstateAgency();
public RealEstateManage()
{
jfFrame = new JFrame ();
jfFrame.add(jpButtons, "North");
jfFrame.add(jpResults,"West");
jfFrame.setSize(900, 400);
jfFrame.setLocation(400, 300);
jfFrame.setTitle("Real Estate Management");
jfFrame.setVisible(true);
}
//Setup the buttons at the top of the GUI
public JPanel setupButtons()
{
JPanel jp = new JPanel ();
jbAddLandlord = new JButton("Add New Landlord");
jbAddProperty = new JButton("Add New Property");
jbAddLease = new JButton("Add New Lease");
jbRecord = new JButton("Record Payment");
jbMaintenance = new JButton("Maintenance");
jbDisplayproperty = new JButton("Display Properties");
jp.add(jbAddLandlord);
jp.add(jbAddProperty);
jp.add(jbAddLease);
jp.add(jbRecord);
jp.add(jbMaintenance);
jp.add(jbDisplayproperty);
jbAddLandlord.addActionListener(this);
jbAddProperty.addActionListener(this);
jbAddLease.addActionListener(this);
jbRecord.addActionListener(this);
jbMaintenance.addActionListener(this);
jbDisplayproperty.addActionListener(this);
return jp;
}
public JPanel setupResults()
{
JPanel jp = new JPanel ();
vlist.add(new Landlord("Fred Jones", "23 Hamilton Road", "0458 789 456", 456123369));
jtfinput1 = new JTextField (10);
jtfinput2 = new JTextField (10);
jtfinput3 = new JTextField (10);
jtfinput4 = new JTextField (10);
ArrayList<Landlord> Alist = R.getLandlords();
jlLandlord = new JList<Landlord>(vlist);
jlLandlord.addListSelectionListener(this);
jlLandlord.setPreferredSize(new Dimension(250, 300));
JLabel jlResults = new JLabel ("Output!");
jtaResults = new JTextArea (18, 30);
jtaResults.setEnabled(false);
jp.add(jlLandlord);
jp.add(jlResults);
jp.add(jtaResults);
return jp;
}
//List Events
@Override
public void valueChanged(ListSelectionEvent arg0) {
// TODO Auto-generated method stub
}
//Button Action Events
public void actionPerformed(ActionEvent ae) {
// Button Events
if(ae.getSource() == jbAddLandlord)
{
addLandlord();
}
if(ae.getSource() == jbAddLandlord)
{
}
}
//Add landlord function
public void addLandlord()
{
boolean inputIsOk = true;
String stName, stAddress, stNum, stBank;
long bank = 0;
JPanel myPanel = new JPanel();
myPanel.add(new JLabel("Name:"));
myPanel.add(jtfinput1);
myPanel.add(new JLabel("Address:"));
myPanel.add(jtfinput2);
myPanel.add(new JLabel("Phone:"));
myPanel.add(jtfinput3);
myPanel.add(new JLabel("Bank Account: (8-10 Digits)"));
myPanel.add(jtfinput4);
int result = JOptionPane.showConfirmDialog(null, myPanel,
"Please Enter X and Y Values", JOptionPane.OK_CANCEL_OPTION);
if (result == JOptionPane.OK_OPTION) {
stName = jtfinput1.getText();
stAddress = jtfinput2.getText();
stNum = jtfinput3.getText();
stBank = jtfinput4.getText();
try{bank = Long.valueOf(stBank).longValue();
}
catch(NumberFormatException nfe){
inputIsOk = false;
}
if (inputIsOk = true){
R.addLandlord(new Landlord(stName, stAddress, stNum, bank));
}
}
// jlLandlord.updateUI();
}
}
文件2
package assignment2;
import java.util.*;
// The RealEstateAgency class is intended to be the central place to go to for finding
// a landlord that the system "knows" about.
public class RealEstateAgency {
private ArrayList<Landlord> allLandlords; // A way of collecting all the Landlords
public RealEstateAgency()
{
// prepare the agency for future landlords...
allLandlords = new ArrayList<Landlord>();
addLandlord(new Landlord("stName", "stAddress", "stNum", 12456897));
System.out.println(getLandlords());
}
// Method to note the provided Landlord, by adding it to the RealEstateAgency's internal ArrayList.
// Returns true if apparently successful, false if something goes wrong such as the landlord already being present.
public boolean addLandlord(Landlord whoToStore)
{
boolean success = false;
if (whoToStore == null) // ensure there is actually a parameter
success = false;
else {
if (allLandlords.contains(whoToStore)) // landlord already in the list
success = false;
else
{ // Landlord not yet in list
allLandlords.add(whoToStore); // So add this landlord
success = true;
}
}
return success;
}
// Method to obtain a landlord from the RealEstateAgency's collection of known landlords,
// by providing the full name. If no such landlord exists, null will be returned.
public Landlord getLandlord(String fullName)
{
Landlord current = null;
boolean found = false;
int index = 0;
while ((!found) && (index < allLandlords.size()))
{
current = allLandlords.get(index);
if (current.getFullName().equals(fullName))
found = true;
else
index++;
}
// If we get to here, and "found" is true, then "current" will be the matching Landlord
if (!found) // did not find a match
current = null; // so ensure we return no Landlord
return current;
}
// Method to obtain an ArrayList containing the same landlords as those which the
// RealEstateAgency knows about (but without exposing the inner ArrayList object
// so that any alterations made to the returned ArrayList won't impact the RealEstateAgency)
public ArrayList<Landlord> getLandlords()
{
ArrayList<Landlord> duplicate;
duplicate = (ArrayList<Landlord>) allLandlords.clone();
return duplicate;
}
public ArrayList<Landlord> getLandlords1()
{
return allLandlords;
}
}
任何帮助或建议都将不胜感激。
我遇到的问题是在setupResults（）函数和getLandlords（）函数中
提前致谢
LANDLORD CODE
package assignment2;
import java.util.*;
// The Landlord class allows you to create objects that encapsulate the key data
// about each Landlord, as well as the information about all the properties that
// they make available for rent (some of which may have current leases active).
public class Landlord {
private String fullName; // The name of the landlord
private String address; // Where the landlord lives!
private String phone; // allow for spaces in number
private long bankAccount; // To permit 10 digits, requires the 'long' data type
private ArrayList<Property> myProperties; // All properties owned by this landlord
public Landlord(String fullName, String address, String phone, long bankAccount)
{
// Simply store the parameters into the fields...
this.fullName = fullName;
this.address = address;
this.phone = phone;
this.bankAccount = bankAccount;
// prepare for future leases...
myProperties = new ArrayList<Property>();
}
// ACCESSORS for each field of basic information
public String getFullName()
{
return fullName;
}
public String getAddress()
{
return address;
}
public String getPhone()
{
return phone;
}
public long getBankAccount()
{
return bankAccount;
}
// Method to note/store another Property, where this Landlord is considered the owner of the property.
// It returns true if successfully added to the list of properties belonging to this landlord.
public boolean addProperty(Property theProperty)
{
boolean result;
if (theProperty == null) // if it is null, we ignore this method call.
result = false;
else if (!myProperties.contains(theProperty)){ // Make sure it is not already in the array list
myProperties.add(theProperty);
result = true;
}
else // This means w have already added the property, so cannot add it again.
result = false;
return result;
}
// Method to return an iterator that may be used to cycle over all leases involving this landlord.
public Iterator<Property> getPropertiesIterator()
{
return myProperties.iterator();
}
public String toString()
{
return "Landlord: " + fullName;
}
}
财产代码
package assignment2;
// The Property class encapsulates the basic information about one property the system knows
// about: essentially the address of the property, and a reference to the Lease details of the property.
public class Property {
private String propertyAddress;
private Lease currentLease; // When null, there is no active lease (it is available).
public Property(String address)
{
this.propertyAddress = address;
this.currentLease = null; // Initially, nobody is leasing it.
}
public String getPropertyAddress()
{
return propertyAddress;
}
// no mutator for address, because it won't ever change.
// Method to return the current lease's details.
public Lease getCurrentLease()
{
return currentLease;
}
// Method to set the current Lease of this Property.
// If null is provided, the property will not have any Lease assigned to it;
// otherwise, the provided Lease will be recorded as describing the relationship for this property.
public void setCurrentLease(Lease newLease)
{
currentLease = newLease;
}
// Method to report whether or not this property is currently associated with a lease (regardless
// of whether fully paid or not)
public boolean isLeased()
{
if (currentLease == null)
return false;
else
return true;
}
public String toString()
{
return "Property: " + propertyAddress;
}
}
租赁代码
package assignment2;
import java.util.*;
// The Lease class encapsulates information about an individual lease of a property by a tenant.
// The data stored here includes all the tenant’s details (name, phone number) as well as
// characteristics of the lease itself such as the duration, the weekly rent amount, how long
// remains in terms of payments, what maintenance has occurred.
public class Lease {
private String tenantFullName; // The name of the person who is living in the leased property.
private String tenantPhone; // Contact number for the person. Allow a leading zero at start, spaces between sections.
private int rentRate; // The amount of rent to be paid each week.
private int leasePeriod; // Either 6 or 12, being a 6 month or 12 month agreement
private int weeksRemaining; // How many weeks remain to be paid for. Initially 26 or 52.
private ArrayList<Maintenance> maintenanceRecord; // record of all maintenance during life of lease
// Create a new lease, recording the following details:
// - tenantName: records the name of the person living in the property
// - tenantPhone: records a contact phone number for the tenant
// - rentRate: the amount of rent which is to be paid each week.
// - leasePeriod: Either 6 or 12, indicating the number of months the lease is to last for.
public Lease(String tenantName, String tenantPhone, int rentRate, int leasePeriod)
{
this.tenantFullName = tenantName;
this.tenantPhone = tenantPhone;
this.rentRate = rentRate;
if (leasePeriod == 12 || leasePeriod == 6) // Check validity of parameter
this.leasePeriod = leasePeriod;
else // if not valid, set to default of 6 month.
this.leasePeriod = 6;
// Determine (automatically) how many weeks the lease is for, and set as initial value
// for the 'weeksRemaining' field:
if (this.leasePeriod == 12)
this.weeksRemaining = 52; // a Year remains to be paid for
else
this.weeksRemaining = 26; // Only half a year remains to be paid for.
// Prepare the lease for future Maintenance records...
maintenanceRecord = new ArrayList<Maintenance>();
}
// ACCESSORS
public String getTenantFullName()
{
return tenantFullName;
}
public String getTenantPhone()
{
return tenantPhone;
}
public int getRentRate()
{
return rentRate;
}
public int getLeasePeriod()
{
return leasePeriod;
}
public int getWeeksRemaining()
{
return weeksRemaining;
}
// Method to reduce the number of weeks remaining to be paid over the period of the lease.
// If the parameter is in excess of the current number of remaining weeks, the method will
// return false, otherwise it returns true and adjusts the number of remaining weeks.
public boolean reduceWeeksRemaining(int howMuch)
{
boolean result;
if (howMuch > weeksRemaining)
result = false;
else
{
weeksRemaining -= howMuch; // Reduces how many weeks remain unpaid.
result = true;
}
return result;
}
// Method to add another maintenance information record to this lease's list of maintenance records.
public void noteMaintenance(String reason, double cost)
{
Maintenance maintInfo = new Maintenance(reason,cost);
maintenanceRecord.add(maintInfo);
}
// Method to return an Iterator that may be used to cycle over all maintenance records for this lease
public Iterator<Maintenance> getMaintenanceRecords()
{
return maintenanceRecord.iterator();
}
}
维护代码
package assignment2;
// The Maintenance class is used to represent an individual occurrence of Maintenance
// and records the cost and description of the maintenance.
public class Maintenance {
private String reason;
private double cost;
public Maintenance(String reason, double cost)
{
this.reason = reason;
this.cost = cost;
}
// ACCESSORS:
public String getReason()
{
return reason;
}
public double getCost()
{
return cost;
}
// Gives a explanation of the cost and reason represented by this Maintenance object.
public String toString()
{
return "$" + cost + " for " + reason;
}
}
答案 0 :(得分：0)
原因是您在setupResults()之前初始化R。
变化：
private JPanel jpButtons = setupButtons(), jpResults = setupResults();
public RealEstateAgency R = new RealEstateAgency();
public RealEstateManage()
{
到
private JPanel jpButtons;
private JPanel jpResults;
public RealEstateAgency R = new RealEstateAgency();
public RealEstateManage()
{
jpButtons = setupButtons();
jpResults = setupResults();
作为旁注： 您将结果视为：
ArrayList<Landlord> Alist = R.getLandlords();
但从不使用该值。 也许你打算写：
ArrayList<Landlord> Alist = R.getLandlords();
jlLandlord = new JList<Landlord>(Alist.toArray(new Landlord[0]));
^ ^^^^^^^^^^^^^^^^^^^^^^^^^
但你没有。