我想创建一个程序，允许用户添加到文件，搜索，删除和加载动物园中的动物文件以及有关它们的信息。按钮删除和搜索到目前为止都没有用，所以不要理会它们。问题是teams和focusGained似乎不起作用。我尝试了迄今为止找到的每个解决方案，但我无法修复它们。所以，所有的帮助表示赞赏。如果您对如何编写搜索和删除类有任何想法，请建议！
这是主程序：
focusLost我划分了程序，所以类GUI_ADD就在这里：
package GUI_Try;
import java.awt.event.*;
import java.util.ArrayList;
import java.io.*;
import javax.swing.*;
import java.awt.*;
public class GUI_ZOO extends JFrame{
ArrayList <ANIMAL> animal= new ArrayList<ANIMAL>();
TextField name,ID,country;
Button add = new Button("add"),
save = new Button("save"),
//delete = new Button("delete"),
//search = new Button("search"),
load = new Button("load");
String sName="",sID="",sCountry="";
JPanel pc;
JScrollPane scrPanName;
JTextArea text;
GUI_ZOO(){
super("Zoo \"Sofia\" ");
setBounds(80, 80, 600, 500);
setDefaultCloseOperation(DISPOSE_ON_CLOSE);
setLayout(new BorderLayout());
GUI_DELETE delObj = new GUI_DELETE();
GUI_SEARCH searchObj = new GUI_SEARCH();
GUI_ADD addObj = new GUI_ADD(sName,name,sID,ID,text,animal,sCountry,country);
pc = new JPanel();
pc.setLayout(new FlowLayout());
text = new JTextArea(20,10);
scrPanName = new JScrollPane(text);
name = new TextField("Name",15);
country = new TextField("Country",15);
ID = new TextField("ID",5);
text.setEditable(false);
pc.add(name);
pc.add(ID);
pc.add(country);
pc.add(add);
pc.add(save);
pc.add(load);
pc.add(search);
pc.add(delete);
ID.addActionListener(addObj);
name.addActionListener(addObj);
country.addActionListener(addObj);
add.addActionListener(addObj);
save.addActionListener(new Save());
load.addActionListener(new Load());
delete.addActionListener(delObj);
search.addActionListener(searchObj);
name.addFocusListener(new Focus()) ;
country.addFocusListener(new Focus()) ;
ID.addFocusListener(new Focus()) ;
add("North",pc);
add("Center",scrPanName);
setVisible(true);
}
class Focus implements FocusListener{
public void focusGained (FocusEvent e){
try{
TextField src = (TextField)e.getSource();
if(src.getText().equals("Name") ){
name.setText("");
}
if(src.getText().equals("ID") ){
ID.setText("");
}
if(src.getText().equals("Country") ){
country.setText("");
}
}
catch(ClassCastException ignored){
}
}
public void focusLost (FocusEvent e){
try{
TextField src = (TextField)e.getSource();
if(src.getText().equals("") ){
name.setText("Name");
}
if(src.getText().equals("") ){
ID.setText("ID");
}
if(src.getText().equals("") ){
country.setText("Country");
}
}
catch(ClassCastException ignored){
}
}
}
class Save implements ActionListener{
public void actionPerformed(ActionEvent e){
try{
ObjectOutputStream os = new ObjectOutputStream(new FileOutputStream("zoo.dat"));
os.writeObject(animal);
os.close();
}
catch(FileNotFoundException ex){
System.out.println("Can't save the file zoo.dat");
}
catch(IOException ex){}
}
}
class Load implements ActionListener{
public void actionPerformed(ActionEvent e){
try{
ObjectInputStream os = new ObjectInputStream(new FileInputStream("zoo.dat"));
animal = (ArrayList<ANIMAL>) os.readObject();
os.close();
text.setText("");
for(ANIMAL a:animal){
text.append(a.name+"\t"+a.ID+"\t"+a.country+"\n");
}
}
catch(FileNotFoundException ex){
System.out.println("Can't find the file zoo.dat");
}
catch(IOException ex){
ex.printStackTrace();//?
}
catch (ClassNotFoundException e1) {
e1.printStackTrace();//?
}
}
}
public static void main(String arg[]){
new GUI_ZOO();
}
}
这是界面：
package GUI_Try;
import java.awt.event.*;
import java.util.ArrayList;
import java.io.*;
import javax.swing.*;
import java.awt.*;
public class GUI_ADD implements ActionListener{
String sNamel;
TextField namel;
String sIDl;
TextField IDl;
String sCountryl;
TextField countryl;
JTextArea textl;
ArrayList <ANIMAL> animall;
public GUI_ADD(String sName,TextField name,String sNumber,TextField ID,
JTextArea text,ArrayList <ANIMAL> animal,String sCountry,TextField country){
sNamel = sName;
sCountryl = sCountry;
IDl = ID;
namel = name;
sIDl = sNumber;
countryl = country;
textl = text;
animall = animal;
}
public void actionPerformed(ActionEvent e){
sNamel=namel.getText();
sIDl=IDl.getText();
sCountryl=countryl.getText();
if((sNamel.length()==0)||(sNamel=="Name")){
JOptionPane.showMessageDialog(null, "Type a name, please.");
return;
}
if(sIDl.length()==0){
JOptionPane.showMessageDialog(null, "Type an ID, please.");
return;
}
if(sCountryl.length()==0){
JOptionPane.showMessageDialog(null, "Type a country of origin, please.");
return;
}
animall.add(new ANIMAL(sNamel,sIDl,sCountryl));
textl.append(sNamel+"\t"+sIDl+"\t"+sCountryl+"\n");
namel.setText("");
IDl.setText("");
countryl.setText("");
}
}
答案 0 :(得分：0)
您的问题（众多问题之一）是混合AWT和Swing组件。
您创建的名称，ID和国家/地区为TextField，然后尝试在JTextField收听者中将其转换为Focus。但是，你可以通过压制它来防范ClassCastException，所以你甚至都看不到这个问题的证据了。
try {
JTextField src = (JTextField) e.getSource();
// ... omitted
} catch(ClassCastException ignored) {
// No-op
}
您希望（需要）在Swing程序中使用JTextField和JButton Swing对象，而不是AWT对象。
focusLost方法的其他问题。如果失去焦点的JTextField为空，则会覆盖您的name，ID和country文字字段...而不仅仅是空白字段！
答案 1 :(得分：0)
您不需要在这两个课程中implements FocusListener。这里多余。
public class GUI_ZOO extends JFrame implements FocusListener{
class Focus implements FocusListener{
FocusGained和FocusLost的原因无效：
TextField name,ID,country;
您使用过java.awt.TextField，
JTextField src = (JTextField)e.getSource();
但您正试图从JTextField获取来源。在你的程序中，你没有任何JTextField的权利！
将其更改为：
TextField src = (TextField)e.getSource();