我的项目分配要求项目实施模式。我选择了“观察者模式”，因为它是最合适的（也请教教授）。
基本上，我必须在Currency Converter项目中自动化更新货币的过程。我创建的Observer / Observable类可以在main方法上完美地运行测试。但是，当我尝试在GUI的jTextArea中传递结果时，不可能使用相同的方法来setText（因为该方法无效）。我也尝试了其他方法约5个小时，但仍然没有完成任何工作。
以下是“观察者模式”的代码（如果要测试，可以完全运行）：
/*This is the observable class*/
import java.util.ArrayList;
import java.util.List;
public class Euro{
private List<Observer> observers = new ArrayList<>();
private double euroToUSD;
public double geteuroToUSD() {
return euroToUSD;
}
public void seteuroToUSD(double euroToUSD) {
this.euroToUSD = euroToUSD;
notifyAllObservers();
}
public void attach(Observer observer){
observers.add(observer);
}
public void notifyAllObservers(){
for (Observer observer : observers) {
observer.update();
}
}
/ 观察者抽象类 /
public abstract class Observer {
protected Euro euro;
public abstract void update();
}
一位观察者（可以根据可观察的输入进行更改）
public class USD extends Observer{
double amt;
public USD(Euro euro, double amt) {
this.euro = euro;
this.euro.attach(this);
this.amt = amt;
}
public USD(){}
@Override
public void update() {
System.out.println(amt*(euro.geteuroToUSD()));
}
}
要运行测试的主类
public class ObserverTest {
public static void main(String[] args) {
Euro euro = new Euro();
new USD(euro, 7); //7 is amount parameter which multiplies with euro(set down there)
System.out.println("First state change: 1.083317");
euro.seteuroToUSD(1.083317);
System.out.println("\nSecond state change: 3");
euro.seteuroToUSD(3);
}
}
这部分实现了其目的。但是，GUI很难做到（也完全可以运行）
public class NewJFrame extends javax.swing.JFrame {
/**
* Creates new form NewJFrame
*/
public NewJFrame() {
initComponents();
}
/**
* This method is called from within the constructor to initialize the form.
* WARNING: Do NOT modify this code. The content of this method is always
* regenerated by the Form Editor.
*/
// <editor-fold defaultstate="collapsed" desc="Generated Code">
private void initComponents() {
jDialog1 = new javax.swing.JDialog();
jPanel1 = new javax.swing.JPanel();
result1 = new javax.swing.JTextField();
result2 = new javax.swing.JTextField();
currency1 = new javax.swing.JComboBox<>();
currency2 = new javax.swing.JComboBox<>();
jButton1 = new javax.swing.JButton();
convert = new javax.swing.JButton();
clear = new javax.swing.JButton();
jLabel1 = new javax.swing.JLabel();
jPanel2 = new javax.swing.JPanel();
org.jdesktop.layout.GroupLayout jDialog1Layout = new org.jdesktop.layout.GroupLayout(jDialog1.getContentPane());
jDialog1.getContentPane().setLayout(jDialog1Layout);
jDialog1Layout.setHorizontalGroup(
jDialog1Layout.createParallelGroup(org.jdesktop.layout.GroupLayout.LEADING)
.add(0, 400, Short.MAX_VALUE)
);
jDialog1Layout.setVerticalGroup(
jDialog1Layout.createParallelGroup(org.jdesktop.layout.GroupLayout.LEADING)
.add(0, 300, Short.MAX_VALUE)
);
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
setTitle("Currency Converter");
setResizable(false);
jPanel1.setLayout(null);
result1.setFont(new java.awt.Font("Consolas", 1, 18)); // NOI18N
result1.setText("1");
result1.setToolTipText("Enter nr you to be converted(you can use either fields)");
result1.addMouseListener(new java.awt.event.MouseAdapter() {
public void mouseClicked(java.awt.event.MouseEvent evt) {
result1MouseClicked(evt);
}
public void mousePressed(java.awt.event.MouseEvent evt) {
result1MousePressed(evt);
}
});
result1.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
result1ActionPerformed(evt);
}
});
jPanel1.add(result1);
result1.setBounds(40, 190, 138, 60);
result2.setFont(new java.awt.Font("Consolas", 1, 18)); // NOI18N
result2.setText("121.8");
result2.setToolTipText("Enter nr you to be converted(you can use either fields)");
result2.addMouseListener(new java.awt.event.MouseAdapter() {
public void mousePressed(java.awt.event.MouseEvent evt) {
result2MousePressed(evt);
}
});
result2.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
result2ActionPerformed(evt);
}
});
jPanel1.add(result2);
result2.setBounds(270, 190, 138, 60);
currency1.setModel(new javax.swing.DefaultComboBoxModel<>(new String[] { "EUR", "ALL", "GBP", "USD" }));
currency1.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
currency1ActionPerformed(evt);
}
});
jPanel1.add(currency1);
currency1.setBounds(30, 30, 138, 52);
currency2.setModel(new javax.swing.DefaultComboBoxModel<>(new String[] { "ALL", "EUR", "USD", "GBP", " " }));
jPanel1.add(currency2);
currency2.setBounds(270, 30, 138, 54);
//jButton1.setIcon(new javax.swing.ImageIcon(getClass().getResource("/IMG/convertIconJavaSmall.png"))); // NOI18N
jButton1.setBorderPainted(false);
jButton1.addMouseListener(new java.awt.event.MouseAdapter() {
public void mouseClicked(java.awt.event.MouseEvent evt) {
jButton1MouseClicked(evt);
}
public void mousePressed(java.awt.event.MouseEvent evt) {
jButton1MousePressed(evt);
}
});
jButton1.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jButton1ActionPerformed(evt);
}
});
jPanel1.add(jButton1);
jButton1.setBounds(190, 110, 55, 52);
convert.setText("Convert");
convert.addMouseListener(new java.awt.event.MouseAdapter() {
public void mouseClicked(java.awt.event.MouseEvent evt) {
convertMouseClicked(evt);
}
});
convert.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
convertActionPerformed(evt);
}
});
jPanel1.add(convert);
convert.setBounds(320, 290, 93, 29);
clear.setEnabled(false);
clear.setText("Clear");
clear.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
clearActionPerformed(evt);
}
});
jPanel1.add(clear);
clear.setBounds(40, 290, 69, 29);
//jLabel1.setIcon(new javax.swing.ImageIcon(getClass().getResource("/GUI/ezgif.com-resize (1).gif"))); // NOI18N
jPanel1.add(jLabel1);
jLabel1.setBounds(40, 0, 440, 380);
jPanel2.setBackground(new java.awt.Color(0, 0, 0));
jPanel2.setLayout(null);
jPanel1.add(jPanel2);
jPanel2.setBounds(0, 0, 460, 380);
org.jdesktop.layout.GroupLayout layout = new org.jdesktop.layout.GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(org.jdesktop.layout.GroupLayout.LEADING)
.add(org.jdesktop.layout.GroupLayout.TRAILING, jPanel1, org.jdesktop.layout.GroupLayout.DEFAULT_SIZE, 454, Short.MAX_VALUE)
);
layout.setVerticalGroup(
layout.createParallelGroup(org.jdesktop.layout.GroupLayout.LEADING)
.add(jPanel1, org.jdesktop.layout.GroupLayout.DEFAULT_SIZE, 380, Short.MAX_VALUE)
);
pack();
setLocationRelativeTo(null);
}// </editor-fold>
private void currency1ActionPerformed(java.awt.event.ActionEvent evt) {
}
private void result1ActionPerformed(java.awt.event.ActionEvent evt) {
}
private void result1MouseClicked(java.awt.event.MouseEvent evt) {
}
private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
String txt1 = (String)currency1.getSelectedItem();
String txt2 = (String)currency2.getSelectedItem();
currency1.setSelectedItem(txt2);
currency2.setSelectedItem(txt1);
}
private void result2ActionPerformed(java.awt.event.ActionEvent evt) {
}
private void jButton1MouseClicked(java.awt.event.MouseEvent evt) {
// TODO add your handling code here:
}
private void result1MousePressed(java.awt.event.MouseEvent evt) {
clear.setEnabled(true);
}
private void jButton1MousePressed(java.awt.event.MouseEvent evt) {
}
private void clearActionPerformed(java.awt.event.ActionEvent evt) {
result1.setText("");
result2.setText("");
}
private void convertActionPerformed(java.awt.event.ActionEvent evt) {
Euro euro = new Euro();
USD usd = new USD(euro, Double.parseDouble(result1.getText()));
System.out.println("\nFirst state change: " + Double.parseDouble(result1.getText()));
euro.seteuroToUSD(1.083317);
System.out.println("\nSecond state change: " + Double.parseDouble(result1.getText()));
euro.seteuroToUSD(3);
double double1 = Double.parseDouble(result1.getText());
double finalResult = double1 * euro.geteuroToUSD();
result2.setText(String.valueOf(finalResult));
// Euro euro = new Euro();
// USD usd = new USD();
// new USD(euro, Double.parseDouble(result1.getText())).toString();
//
// euro.seteuroToUSD(1.083317);
//
//
//
//// new USD(euro, 123);
// if("EUR".equals(currency1.getSelectedItem().toString()) && "USD".equals(currency2.getSelectedItem().toString())){
//
//
//
// result2.setText(total);
// Euro euro = new Euro();
// USD usd = new USD(euro, Double.parseDouble(result1.getText()));
// double secondresult;
//
// if("EUR".equals(currency1.getSelectedItem().toString()) && "USD".equals(currency2.getSelectedItem().toString())){
//
//
//
// result2.setText(String.valueOf(euro.geteuroToUSD()));
// EUR EUR = new EUR();
// USD USD = new USD();
// ALL ALL = new ALL();
// GBP GBP = new GBP();
// Double Double.parseDouble(result1.getText()) = Double.parseDouble(result1.getText()); //Convert entered nr to double
// double secondresult; //Create container for calc between 2 currencies
//
////EURO TO EVERYTHING ELSE
//String txt1 = (String)result1.getText();
//String txt2 = (String)result2.getText();
//
//try{
//if ("".equals(txt1) && "".equals(txt2)){
// JOptionPane.showMessageDialog(null, "Input a nr in txtArea");
//
//
// }else if("EUR".equals(currency1.getSelectedItem().toString()) && "USD".equals(currency2.getSelectedItem().toString())){
// secondresult = Double.parseDouble(result1.getText()) * EUR.getRateToUSD();
// result2.setText(String.valueOf(secondresult));
//
// }else if("USD".equals(currency1.getSelectedItem().toString()) && "EUR".equals(currency2.getSelectedItem().toString())){
// secondresult = Double.parseDouble(result1.getText()) * USD.getRateToEUR();
// result2.setText(String.valueOf(secondresult));
//
///*breathe
//--------------------------------------------------------------------------------*/
//
// }else if(currency1.getSelectedItem().toString() == "EUR" && currency2.getSelectedItem().toString() == "ALL"){
// secondresult = Double.parseDouble(result1.getText()) * EUR.getRateToALL();
// result2.setText(String.valueOf(secondresult));
//
// }else if(currency1.getSelectedItem().toString() == "ALL" && currency2.getSelectedItem().toString() == "EUR"){
// secondresult = Double.parseDouble(result1.getText()) * ALL.getRateToEUR();
// result2.setText(String.valueOf(secondresult));
//
// /*breathe
//--------------------------------------------------------------------------------*/
//
// }else if(currency1.getSelectedItem().toString() == "EUR" && currency2.getSelectedItem().toString() == "GBP"){
// secondresult = Double.parseDouble(result1.getText()) * EUR.getRateToGBP();
// result2.setText(String.valueOf(secondresult));
//
// }else if(currency1.getSelectedItem().toString() == "GBP" && currency2.getSelectedItem().toString() == "EUR"){
// secondresult = Double.parseDouble(result1.getText()) * GBP.getRateToEUR();
// result2.setText(String.valueOf(secondresult));
//
///*breathe
//--------------------------------------------------------------------------------*/
////USD to ALL, GBP
// }else if(currency1.getSelectedItem().toString() == "USD" && currency2.getSelectedItem().toString() == "ALL"){
// secondresult = Double.parseDouble(result1.getText()) * USD.getRateToALL();
// result2.setText(String.valueOf(secondresult));
//
// }else if(currency1.getSelectedItem().toString() == "ALL" && currency2.getSelectedItem().toString() == "USD"){
// secondresult = Double.parseDouble(result1.getText()) * ALL.getRateToUSD();
// result2.setText(String.valueOf(secondresult));
//
///*breathe
//--------------------------------------------------------------------------------*/
// }else if(currency1.getSelectedItem().toString() == "USD" && currency2.getSelectedItem().toString() == "GBP"){
// secondresult = Double.parseDouble(result1.getText()) * USD.getRateToGBP();
// result2.setText(String.valueOf(secondresult));
//
// }else if(currency1.getSelectedItem().toString() == "GBP" && currency2.getSelectedItem().toString() == "USD"){
// secondresult = Double.parseDouble(result1.getText()) * GBP.getRateToUSD();
// result2.setText(String.valueOf(secondresult));
//
//
//
//
///*breathe
//--------------------------------------------------------------------------------*/
////ALL to GBP
// }else if(currency1.getSelectedItem().toString() == "ALL" && currency2.getSelectedItem().toString() == "GBP"){
// secondresult = Double.parseDouble(result1.getText()) * ALL.getRateToGBP();
// result2.setText(String.valueOf(secondresult));
//
// }else if(currency1.getSelectedItem().toString() == "GBP" && currency2.getSelectedItem().toString() == "ALL"){
// secondresult = Double.parseDouble(result1.getText()) * GBP.getRateToALL();
// result2.setText(String.valueOf(secondresult));
//
// }
// }catch(NumberFormatException e){
// JOptionPane.showMessageDialog(this, "Try to type a number ;)");
// }
//
//
//END CONVERT BUTTON
//}
}
private void convertMouseClicked(java.awt.event.MouseEvent evt) {
}
private void result2MousePressed(java.awt.event.MouseEvent evt) {
clear.setEnabled(true);
}
/**
* @param args the command line arguments
*/
public static void main(String args[]) {
/* Set the Nimbus look and feel */
//<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
/* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
* For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html
*/
try {
for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
if ("Nimbus".equals(info.getName())) {
javax.swing.UIManager.setLookAndFeel(info.getClassName());
break;
}
}
} catch (ClassNotFoundException ex) {
java.util.logging.Logger.getLogger(NewJFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (InstantiationException ex) {
java.util.logging.Logger.getLogger(NewJFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (IllegalAccessException ex) {
java.util.logging.Logger.getLogger(NewJFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (javax.swing.UnsupportedLookAndFeelException ex) {
java.util.logging.Logger.getLogger(NewJFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
}
//</editor-fold>
/* Create and display the form */
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
new NewJFrame().setVisible(true);
}
});
}
// Variables declaration - do not modify
private javax.swing.JButton clear;
private javax.swing.JButton convert;
private javax.swing.JComboBox<String> currency1;
private javax.swing.JComboBox<String> currency2;
private javax.swing.JButton jButton1;
private javax.swing.JDialog jDialog1;
private javax.swing.JLabel jLabel1;
private javax.swing.JPanel jPanel1;
private javax.swing.JPanel jPanel2;
private javax.swing.JTextField result1;
private javax.swing.JTextField result2;
// End of variables declaration
}
我要更改的部分是：
private void convertActionPerformed(java.awt.event.ActionEvent evt) {
Euro euro = new Euro();
USD usd = new USD(euro, Double.parseDouble(result1.getText()));
System.out.println("\nFirst state change: " + Double.parseDouble(result1.getText()));
euro.seteuroToUSD(1.083317);
System.out.println("\nSecond state change: " + Double.parseDouble(result1.getText()));
euro.seteuroToUSD(3);
double double1 = Double.parseDouble(result1.getText());
double finalResult = double1 * euro.geteuroToUSD();
result2.setText(String.valueOf(finalResult));
我对这个问题的解决方案确实是静态的，与观察者模式哲学完全相反。非常感谢您的帮助：）