java 获取堆栈溢出程序不是递归的
java getting stack overflow-program is not recursive
我一直在研究我的 "Random Trivia" 程序，但我一直在没有递归的情况下出现堆栈溢出，至少我找不到任何东西，这是 Gui.java 的代码，主要 class（而且只有 class）
package mods.giantnuker.random_trivia;
import java.awt.event.ActionEvent;
import org.w3c.dom.Element;
import org.w3c.dom.NodeList;
import java.awt.event.ActionListener;
import java.awt.event.ItemEvent;
import java.awt.event.ItemListener;
import java.io.File;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import javax.swing.BoxLayout;
import javax.swing.JButton;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.transform.TransformerException;
import javax.xml.transform.TransformerFactoryConfigurationError;
import mods.giantnuker.javautil.FileFilterAccessor;
import mods.giantnuker.javautil.Pair;
import mods.giantnuker.javautil.PairList;
import mods.giantnuker.javautil.file.parser.XMLParser;
import javax.swing.JFileChooser;
@SuppressWarnings("serial")
public class Gui extends JFrame implements ActionListener, ItemListener {
String tsn;
JFileChooser dialg;
JPanel welcome, newt;
JButton sbttn, nbttn, ebttn, nqb, nab, dqb, dab, sav, ext;
@SuppressWarnings("rawtypes")
JComboBox questions, answers;
List<Pair<String, PairList<String, Integer>>> trivia;
public static void main(String[] args) {
new Gui();
}
@SuppressWarnings({ "static-access", "rawtypes" })
public Gui() {
super("Random Trivia");
this.setSize(300, 250);
this.setDefaultCloseOperation(this.EXIT_ON_CLOSE);
//New
newt = new JPanel();
newt.setLayout(new BoxLayout(newt, BoxLayout.Y_AXIS));
questions = new JComboBox();
questions.addItemListener(this);
answers = new JComboBox();
nqb = new JButton("New Question+ ");
nab = new JButton("New Answer+ ");
dqb = new JButton("-Delete Question");
dab = new JButton("-Delete Answer ");
sav = new JButton("*Save ");
ext = new JButton("-Exit- ");
nqb.addActionListener(this);
nab.addActionListener(this);
dqb.addActionListener(this);
dab.addActionListener(this);
sav.addActionListener(this);
ext.addActionListener(this);
newt.add(questions);
newt.add(answers);
newt.add(nqb);
newt.add(nab);
newt.add(dqb);
newt.add(dab);
newt.add(sav);
newt.add(ext);
//Welcome
welcome = new JPanel();
welcome.setLayout(new BoxLayout(welcome, BoxLayout.Y_AXIS));
welcome.add(new JLabel("Welcome To Random Trivia!"));
welcome.add(sbttn = new JButton("Select a file(.trv) to use"));
welcome.add(nbttn = new JButton("Create a new one"));
welcome.add(ebttn = new JButton("Or edit an old one"));
sbttn.addActionListener(this);
nbttn.addActionListener(this);
ebttn.addActionListener(this);
dialg = new JFileChooser();
dialg.setDialogType(dialg.OPEN_DIALOG);
dialg.setFileFilter(new FileFilterAccessor("trv"));
this.add(welcome);
this.setVisible(true);
}
@SuppressWarnings({ "unchecked", "rawtypes", "static-access" })
@Override
public void actionPerformed(ActionEvent arg0) {
Object src = arg0.getSource();
if (src == sbttn) {
dialg.setDialogType(dialg.OPEN_DIALOG);
List<Map<String, Integer>> trivia = new ArrayList();
int out = dialg.showOpenDialog(null);
if(out == 0) {
File f = dialg.getSelectedFile();
}
}
if (src == nbttn) {
trivia = new ArrayList();
this.remove(welcome);
this.add(newt);
this.setVisible(true);
}
if (src == ebttn) {
dialg.setDialogType(dialg.OPEN_DIALOG);
int out = dialg.showOpenDialog(null);
if(out == 0) {
trivia = parse(dialg.getSelectedFile());
this.remove(welcome);
this.add(newt);
ref();
this.setVisible(true);
}
}
if (src == ext) {
this.remove(newt);
this.add(welcome);
this.setVisible(true);
}
if (src == nqb) {
String txt = JOptionPane.showInputDialog(this ,"Enter the Question:", "Question...");
if (txt.length() > 0 && !txt.equals("Question...")) {
trivia.add(new Pair(txt, new PairList()));
questions.addItem(txt);
}
}
if (src == nab) {
if (questions.getItemCount() == 0) {
JOptionPane.showMessageDialog(this, "You must select a question or create one!", "Error", JOptionPane.WARNING_MESSAGE);
return;
}
String txt = JOptionPane.showInputDialog(this ,"Enter the Answer:", "Answer...");
String txt2 = JOptionPane.showInputDialog(this ,"Enter the amount of points for the Answer:", "Points...");
if (txt.length() > 0 && !txt.equals("Answer...")) {
if (txt2.length() > 0 && !txt2.equals("Points...")) {
int points = 0;
boolean err = true;
while(err) {
try {
points = Integer.valueOf(txt2);
err = false;
} catch (NumberFormatException e) {
txt2 = JOptionPane.showInputDialog(this ,"Enter the amount of points for the Answer:", "Points...");
if (txt2.equals("Points...")) return;
}
}
trivia.get(questions.getSelectedIndex()).getB().add(txt, points);
answers.addItem(txt + "(" + points + " points)");
}
}
}
if (src == dab) {
if (questions.getItemCount() == 0) {
JOptionPane.showMessageDialog(this, "You must select a question!", "Error", JOptionPane.WARNING_MESSAGE);
return;
}
if (answers.getItemCount() != 0) {
trivia.get(questions.getSelectedIndex()).getB().remove(answers.getSelectedIndex());
answers.removeItemAt(answers.getSelectedIndex());
}
}
if (src == dqb) {
if (questions.getItemCount() != 0) {
trivia.remove(trivia.get(questions.getSelectedIndex()));
questions.removeItemAt(questions.getSelectedIndex());
ref();
}
}
if (src == sav) {
tsn = JOptionPane.showInputDialog(this ,"Enter the name of the Trivia:", "Name...");
if (!tsn.equals("Name...")) newTriviaSave();
}
}
@SuppressWarnings("static-access")
public void newTriviaSave() {
dialg.setDialogType(dialg.SAVE_DIALOG);
int out = dialg.showSaveDialog(null);
if(out == 0) {
File f = dialg.getSelectedFile();
if (!f.getPath().contains(".")) {
f = new File(f.getPath() + ".trv");
}
System.out.println(f.getPath());
toFile(f, trivia, tsn);
}
}
@SuppressWarnings({ "unchecked", "rawtypes" })
public List<Pair<String, PairList<String, Integer>>> parse(File f) {
List<Pair<String, PairList<String, Integer>>> trivia = new ArrayList();
XMLParser p = new XMLParser(f);
try {
p.read();
p.doc.getDocumentElement().normalize();
NodeList l = p.doc.getElementsByTagName("trivia");
Element root = (Element) l.item(0);
tsn = root.getAttribute("name");
l = root.getElementsByTagName("question");
for (int i = 0; i < l.getLength(); i++) {
Element question = (Element)l.item(i);
NodeList l2 = question.getElementsByTagName("answer");
PairList<String, Integer> answers = new PairList();
for (int j = 0; j < l2.getLength(); j++) {
Element answer = (Element)l2.item(j);
answers.add(answer.getAttribute("text"), Integer.valueOf(answer.getAttribute("points")));
}
trivia.add(new Pair(question.getAttribute("text"), answers));
}
} catch (Exception e) {
}
return trivia;
}
public void toFile(File f, List<Pair<String, PairList<String, Integer>>> questions, String name) {
XMLParser p = new XMLParser(f);
try {
p.create();
Element root = p.doc.createElement("trivia");
root.setAttribute("name", name);
for (Pair<String, PairList<String, Integer>> question : questions) {
Element questionE = p.doc.createElement("question");
questionE.setAttribute("text", question.getA());
for (Pair<String, Integer> answer : question.getB()) {
Element answerE = p.doc.createElement("answer");
answerE.setAttribute("text", answer.getA());
answerE.setAttribute("points", String.valueOf(answer.getB()));
questionE.appendChild(answerE);
}
root.appendChild(questionE);
}
p.doc.appendChild(root);
p.write();
} catch (ParserConfigurationException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (TransformerFactoryConfigurationError e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (TransformerException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
@Override
public void itemStateChanged(ItemEvent arg0) {
Object src = arg0.getSource();
if (src == questions) {
ref();
}
}
@SuppressWarnings("unchecked")
public void ref() {
questions.removeAllItems();
answers.removeAllItems();
for (Pair<String, PairList<String, Integer>> p : trivia) {
questions.addItem(p.getA());
}
if (questions.getItemCount() != 0) {
PairList<String, Integer> answes = trivia.get(questions.getSelectedIndex()).getB();
for (Pair<String, Integer> ans : answes) {
answers.addItem(ans.getA() + "(" + ans.getB() + " points)");
}
}
}
}
JavaUtil 工作正常 - 与其无关。
Here 是一个预打包了 JavaUtil 的可运行 jar。
要得到我的错误，请单击 "edit an old one" 并打开以下文件（只是一个虚拟文件，您可以自己制作并获得相同的结果）
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<trivia name="Dummy Trivia">
<question text="dum">
<answer points="1" text="ans1"/>
</question><question text="dum2">
<answer points="1" text="ans1"/>
<answer points="2" text="ans2"/>
</question>
<question text="dum3">
<answer points="1" text="ans1"/>
<answer points="2" text="ans2"/>
<answer points="3" text="ans3"/>
</question>
</trivia>
谢谢:)
EDIT: 堆栈溢出在 ref() \ 代表刷新
Exception in thread "AWT-EventQueue-0" java.lang.WhosebugError
at javax.swing.plaf.basic.BasicComboBoxUI$Handler.contentsChanged(BasicComboBoxUI.java:1858)
at javax.swing.plaf.basic.BasicComboBoxUI$Handler.intervalRemoved(BasicComboBoxUI.java:1877)
at javax.swing.AbstractListModel.fireIntervalRemoved(AbstractListModel.java:179)
at javax.swing.DefaultComboBoxModel.removeAllElements(DefaultComboBoxModel.java:174)
at javax.swing.JComboBox.removeAllItems(JComboBox.java:771)
at mods.giantnuker.random_trivia.Gui.ref(Gui.java:264)
at mods.giantnuker.random_trivia.Gui.itemStateChanged(Gui.java:258)
at javax.swing.JComboBox.fireItemStateChanged(JComboBox.java:1223)
at javax.swing.JComboBox.selectedItemChanged(JComboBox.java:1280)
at javax.swing.JComboBox.contentsChanged(JComboBox.java:1329)
at javax.swing.AbstractListModel.fireContentsChanged(AbstractListModel.java:118)
at javax.swing.DefaultComboBoxModel.setSelectedItem(DefaultComboBoxModel.java:93)
at javax.swing.DefaultComboBoxModel.addElement(DefaultComboBoxModel.java:131)
at javax.swing.JComboBox.addItem(JComboBox.java:716)
at mods.giantnuker.random_trivia.Gui.ref(Gui.java:267)
at mods.giantnuker.random_trivia.Gui.itemStateChanged(Gui.java:258)
at javax.swing.JComboBox.fireItemStateChanged(JComboBox.java:1223)
at javax.swing.JComboBox.selectedItemChanged(JComboBox.java:1271)
at javax.swing.JComboBox.contentsChanged(JComboBox.java:1329)
at javax.swing.JComboBox.intervalRemoved(JComboBox.java:1351)
at javax.swing.AbstractListModel.fireIntervalRemoved(AbstractListModel.java:179)
at javax.swing.DefaultComboBoxModel.removeAllElements(DefaultComboBoxModel.java:174)
at javax.swing.JComboBox.removeAllItems(JComboBox.java:771)
at mods.giantnuker.random_trivia.Gui.ref(Gui.java:264)
at mods.giantnuker.random_trivia.Gui.itemStateChanged(Gui.java:258)
at javax.swing.JComboBox.fireItemStateChanged(JComboBox.java:1223)
at javax.swing.JComboBox.selectedItemChanged(JComboBox.java:1280)
at javax.swing.JComboBox.contentsChanged(JComboBox.java:1329)
at javax.swing.AbstractListModel.fireContentsChanged(AbstractListModel.java:118)
at javax.swing.DefaultComboBoxModel.setSelectedItem(DefaultComboBoxModel.java:93)
at javax.swing.DefaultComboBoxModel.addElement(DefaultComboBoxModel.java:131)
at javax.swing.JComboBox.addItem(JComboBox.java:716)
at mods.giantnuker.random_trivia.Gui.ref(Gui.java:267)
继续...
boolean err = true;
while(err) {
try {
points = Integer.valueOf(txt2);
err = false;
} catch (NumberFormatException e) {
txt2 = JOptionPane.showInputDialog(this, "Enter the amount of points for the Answer:", "Points...");
if (txt2.equals("Points..."))
return;
}
}
我正在调查此事。如果 text2 不是数字，它将抛出异常，并且不会将 err 设置为 false。假设 text2 不等于 "Points..."
，这可能会导致循环无限继续下去
查看您的堆栈跟踪，我们发现问题集中在 ref() 方法和从 JComboBox 中删除组件。
这里似乎有问题：
@Override
public void itemStateChanged(ItemEvent arg0) {
Object src = arg0.getSource();
if (src == questions) {
ref();
}
}
@SuppressWarnings("unchecked")
public void ref() {
questions.removeAllItems();
answers.removeAllItems();
...
您的 ItemListener，（this -- 已添加到问题和答案 JComboBoxes 中）调用 ref() 方法，该方法更改两个 JComboBox 的状态，触发 ItemListener，后者调用ref() 方法 ..... 无穷无尽。
不要从其中一个侦听器中更改对象的状态，或者如果您绝对需要这样做，请先停用或删除侦听器，然后重新添加它们。例如，
public void ref() {
// first remove all item listeners
ItemListener[] questionListeners = questions.getItemListeners();
ItemListener[] answerListeners = answers.getItemListeners();
for (ItemListener l : questionListeners) {
questions.removeItemListener(l);
}
for (ItemListener l : answerListeners) {
answers.removeItemListener(l);
}
// change state
questions.removeAllItems();
answers.removeAllItems();
// re-add all listeners
for (ItemListener l : questionListeners) {
questions.addItemListener(l);
}
for (ItemListener l : answerListeners) {
answers.addItemListener(l);
}
...
我一直在研究我的 "Random Trivia" 程序，但我一直在没有递归的情况下出现堆栈溢出，至少我找不到任何东西，这是 Gui.java 的代码，主要 class（而且只有 class）
package mods.giantnuker.random_trivia;
import java.awt.event.ActionEvent;
import org.w3c.dom.Element;
import org.w3c.dom.NodeList;
import java.awt.event.ActionListener;
import java.awt.event.ItemEvent;
import java.awt.event.ItemListener;
import java.io.File;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import javax.swing.BoxLayout;
import javax.swing.JButton;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.transform.TransformerException;
import javax.xml.transform.TransformerFactoryConfigurationError;
import mods.giantnuker.javautil.FileFilterAccessor;
import mods.giantnuker.javautil.Pair;
import mods.giantnuker.javautil.PairList;
import mods.giantnuker.javautil.file.parser.XMLParser;
import javax.swing.JFileChooser;
@SuppressWarnings("serial")
public class Gui extends JFrame implements ActionListener, ItemListener {
String tsn;
JFileChooser dialg;
JPanel welcome, newt;
JButton sbttn, nbttn, ebttn, nqb, nab, dqb, dab, sav, ext;
@SuppressWarnings("rawtypes")
JComboBox questions, answers;
List<Pair<String, PairList<String, Integer>>> trivia;
public static void main(String[] args) {
new Gui();
}
@SuppressWarnings({ "static-access", "rawtypes" })
public Gui() {
super("Random Trivia");
this.setSize(300, 250);
this.setDefaultCloseOperation(this.EXIT_ON_CLOSE);
//New
newt = new JPanel();
newt.setLayout(new BoxLayout(newt, BoxLayout.Y_AXIS));
questions = new JComboBox();
questions.addItemListener(this);
answers = new JComboBox();
nqb = new JButton("New Question+ ");
nab = new JButton("New Answer+ ");
dqb = new JButton("-Delete Question");
dab = new JButton("-Delete Answer ");
sav = new JButton("*Save ");
ext = new JButton("-Exit- ");
nqb.addActionListener(this);
nab.addActionListener(this);
dqb.addActionListener(this);
dab.addActionListener(this);
sav.addActionListener(this);
ext.addActionListener(this);
newt.add(questions);
newt.add(answers);
newt.add(nqb);
newt.add(nab);
newt.add(dqb);
newt.add(dab);
newt.add(sav);
newt.add(ext);
//Welcome
welcome = new JPanel();
welcome.setLayout(new BoxLayout(welcome, BoxLayout.Y_AXIS));
welcome.add(new JLabel("Welcome To Random Trivia!"));
welcome.add(sbttn = new JButton("Select a file(.trv) to use"));
welcome.add(nbttn = new JButton("Create a new one"));
welcome.add(ebttn = new JButton("Or edit an old one"));
sbttn.addActionListener(this);
nbttn.addActionListener(this);
ebttn.addActionListener(this);
dialg = new JFileChooser();
dialg.setDialogType(dialg.OPEN_DIALOG);
dialg.setFileFilter(new FileFilterAccessor("trv"));
this.add(welcome);
this.setVisible(true);
}
@SuppressWarnings({ "unchecked", "rawtypes", "static-access" })
@Override
public void actionPerformed(ActionEvent arg0) {
Object src = arg0.getSource();
if (src == sbttn) {
dialg.setDialogType(dialg.OPEN_DIALOG);
List<Map<String, Integer>> trivia = new ArrayList();
int out = dialg.showOpenDialog(null);
if(out == 0) {
File f = dialg.getSelectedFile();
}
}
if (src == nbttn) {
trivia = new ArrayList();
this.remove(welcome);
this.add(newt);
this.setVisible(true);
}
if (src == ebttn) {
dialg.setDialogType(dialg.OPEN_DIALOG);
int out = dialg.showOpenDialog(null);
if(out == 0) {
trivia = parse(dialg.getSelectedFile());
this.remove(welcome);
this.add(newt);
ref();
this.setVisible(true);
}
}
if (src == ext) {
this.remove(newt);
this.add(welcome);
this.setVisible(true);
}
if (src == nqb) {
String txt = JOptionPane.showInputDialog(this ,"Enter the Question:", "Question...");
if (txt.length() > 0 && !txt.equals("Question...")) {
trivia.add(new Pair(txt, new PairList()));
questions.addItem(txt);
}
}
if (src == nab) {
if (questions.getItemCount() == 0) {
JOptionPane.showMessageDialog(this, "You must select a question or create one!", "Error", JOptionPane.WARNING_MESSAGE);
return;
}
String txt = JOptionPane.showInputDialog(this ,"Enter the Answer:", "Answer...");
String txt2 = JOptionPane.showInputDialog(this ,"Enter the amount of points for the Answer:", "Points...");
if (txt.length() > 0 && !txt.equals("Answer...")) {
if (txt2.length() > 0 && !txt2.equals("Points...")) {
int points = 0;
boolean err = true;
while(err) {
try {
points = Integer.valueOf(txt2);
err = false;
} catch (NumberFormatException e) {
txt2 = JOptionPane.showInputDialog(this ,"Enter the amount of points for the Answer:", "Points...");
if (txt2.equals("Points...")) return;
}
}
trivia.get(questions.getSelectedIndex()).getB().add(txt, points);
answers.addItem(txt + "(" + points + " points)");
}
}
}
if (src == dab) {
if (questions.getItemCount() == 0) {
JOptionPane.showMessageDialog(this, "You must select a question!", "Error", JOptionPane.WARNING_MESSAGE);
return;
}
if (answers.getItemCount() != 0) {
trivia.get(questions.getSelectedIndex()).getB().remove(answers.getSelectedIndex());
answers.removeItemAt(answers.getSelectedIndex());
}
}
if (src == dqb) {
if (questions.getItemCount() != 0) {
trivia.remove(trivia.get(questions.getSelectedIndex()));
questions.removeItemAt(questions.getSelectedIndex());
ref();
}
}
if (src == sav) {
tsn = JOptionPane.showInputDialog(this ,"Enter the name of the Trivia:", "Name...");
if (!tsn.equals("Name...")) newTriviaSave();
}
}
@SuppressWarnings("static-access")
public void newTriviaSave() {
dialg.setDialogType(dialg.SAVE_DIALOG);
int out = dialg.showSaveDialog(null);
if(out == 0) {
File f = dialg.getSelectedFile();
if (!f.getPath().contains(".")) {
f = new File(f.getPath() + ".trv");
}
System.out.println(f.getPath());
toFile(f, trivia, tsn);
}
}
@SuppressWarnings({ "unchecked", "rawtypes" })
public List<Pair<String, PairList<String, Integer>>> parse(File f) {
List<Pair<String, PairList<String, Integer>>> trivia = new ArrayList();
XMLParser p = new XMLParser(f);
try {
p.read();
p.doc.getDocumentElement().normalize();
NodeList l = p.doc.getElementsByTagName("trivia");
Element root = (Element) l.item(0);
tsn = root.getAttribute("name");
l = root.getElementsByTagName("question");
for (int i = 0; i < l.getLength(); i++) {
Element question = (Element)l.item(i);
NodeList l2 = question.getElementsByTagName("answer");
PairList<String, Integer> answers = new PairList();
for (int j = 0; j < l2.getLength(); j++) {
Element answer = (Element)l2.item(j);
answers.add(answer.getAttribute("text"), Integer.valueOf(answer.getAttribute("points")));
}
trivia.add(new Pair(question.getAttribute("text"), answers));
}
} catch (Exception e) {
}
return trivia;
}
public void toFile(File f, List<Pair<String, PairList<String, Integer>>> questions, String name) {
XMLParser p = new XMLParser(f);
try {
p.create();
Element root = p.doc.createElement("trivia");
root.setAttribute("name", name);
for (Pair<String, PairList<String, Integer>> question : questions) {
Element questionE = p.doc.createElement("question");
questionE.setAttribute("text", question.getA());
for (Pair<String, Integer> answer : question.getB()) {
Element answerE = p.doc.createElement("answer");
answerE.setAttribute("text", answer.getA());
answerE.setAttribute("points", String.valueOf(answer.getB()));
questionE.appendChild(answerE);
}
root.appendChild(questionE);
}
p.doc.appendChild(root);
p.write();
} catch (ParserConfigurationException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (TransformerFactoryConfigurationError e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (TransformerException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
@Override
public void itemStateChanged(ItemEvent arg0) {
Object src = arg0.getSource();
if (src == questions) {
ref();
}
}
@SuppressWarnings("unchecked")
public void ref() {
questions.removeAllItems();
answers.removeAllItems();
for (Pair<String, PairList<String, Integer>> p : trivia) {
questions.addItem(p.getA());
}
if (questions.getItemCount() != 0) {
PairList<String, Integer> answes = trivia.get(questions.getSelectedIndex()).getB();
for (Pair<String, Integer> ans : answes) {
answers.addItem(ans.getA() + "(" + ans.getB() + " points)");
}
}
}
}
JavaUtil 工作正常 - 与其无关。
Here 是一个预打包了 JavaUtil 的可运行 jar。 要得到我的错误，请单击 "edit an old one" 并打开以下文件（只是一个虚拟文件，您可以自己制作并获得相同的结果）
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<trivia name="Dummy Trivia">
<question text="dum">
<answer points="1" text="ans1"/>
</question><question text="dum2">
<answer points="1" text="ans1"/>
<answer points="2" text="ans2"/>
</question>
<question text="dum3">
<answer points="1" text="ans1"/>
<answer points="2" text="ans2"/>
<answer points="3" text="ans3"/>
</question>
</trivia>
谢谢:)
EDIT: 堆栈溢出在 ref() \ 代表刷新
Exception in thread "AWT-EventQueue-0" java.lang.WhosebugError
at javax.swing.plaf.basic.BasicComboBoxUI$Handler.contentsChanged(BasicComboBoxUI.java:1858)
at javax.swing.plaf.basic.BasicComboBoxUI$Handler.intervalRemoved(BasicComboBoxUI.java:1877)
at javax.swing.AbstractListModel.fireIntervalRemoved(AbstractListModel.java:179)
at javax.swing.DefaultComboBoxModel.removeAllElements(DefaultComboBoxModel.java:174)
at javax.swing.JComboBox.removeAllItems(JComboBox.java:771)
at mods.giantnuker.random_trivia.Gui.ref(Gui.java:264)
at mods.giantnuker.random_trivia.Gui.itemStateChanged(Gui.java:258)
at javax.swing.JComboBox.fireItemStateChanged(JComboBox.java:1223)
at javax.swing.JComboBox.selectedItemChanged(JComboBox.java:1280)
at javax.swing.JComboBox.contentsChanged(JComboBox.java:1329)
at javax.swing.AbstractListModel.fireContentsChanged(AbstractListModel.java:118)
at javax.swing.DefaultComboBoxModel.setSelectedItem(DefaultComboBoxModel.java:93)
at javax.swing.DefaultComboBoxModel.addElement(DefaultComboBoxModel.java:131)
at javax.swing.JComboBox.addItem(JComboBox.java:716)
at mods.giantnuker.random_trivia.Gui.ref(Gui.java:267)
at mods.giantnuker.random_trivia.Gui.itemStateChanged(Gui.java:258)
at javax.swing.JComboBox.fireItemStateChanged(JComboBox.java:1223)
at javax.swing.JComboBox.selectedItemChanged(JComboBox.java:1271)
at javax.swing.JComboBox.contentsChanged(JComboBox.java:1329)
at javax.swing.JComboBox.intervalRemoved(JComboBox.java:1351)
at javax.swing.AbstractListModel.fireIntervalRemoved(AbstractListModel.java:179)
at javax.swing.DefaultComboBoxModel.removeAllElements(DefaultComboBoxModel.java:174)
at javax.swing.JComboBox.removeAllItems(JComboBox.java:771)
at mods.giantnuker.random_trivia.Gui.ref(Gui.java:264)
at mods.giantnuker.random_trivia.Gui.itemStateChanged(Gui.java:258)
at javax.swing.JComboBox.fireItemStateChanged(JComboBox.java:1223)
at javax.swing.JComboBox.selectedItemChanged(JComboBox.java:1280)
at javax.swing.JComboBox.contentsChanged(JComboBox.java:1329)
at javax.swing.AbstractListModel.fireContentsChanged(AbstractListModel.java:118)
at javax.swing.DefaultComboBoxModel.setSelectedItem(DefaultComboBoxModel.java:93)
at javax.swing.DefaultComboBoxModel.addElement(DefaultComboBoxModel.java:131)
at javax.swing.JComboBox.addItem(JComboBox.java:716)
at mods.giantnuker.random_trivia.Gui.ref(Gui.java:267)
继续...
boolean err = true;
while(err) {
try {
points = Integer.valueOf(txt2);
err = false;
} catch (NumberFormatException e) {
txt2 = JOptionPane.showInputDialog(this, "Enter the amount of points for the Answer:", "Points...");
if (txt2.equals("Points..."))
return;
}
}
我正在调查此事。如果 text2 不是数字，它将抛出异常，并且不会将 err 设置为 false。假设 text2 不等于 "Points..."
查看您的堆栈跟踪，我们发现问题集中在 ref() 方法和从 JComboBox 中删除组件。
这里似乎有问题：
@Override
public void itemStateChanged(ItemEvent arg0) {
Object src = arg0.getSource();
if (src == questions) {
ref();
}
}
@SuppressWarnings("unchecked")
public void ref() {
questions.removeAllItems();
answers.removeAllItems();
...
您的 ItemListener，（this -- 已添加到问题和答案 JComboBoxes 中）调用 ref() 方法，该方法更改两个 JComboBox 的状态，触发 ItemListener，后者调用ref() 方法 ..... 无穷无尽。
不要从其中一个侦听器中更改对象的状态，或者如果您绝对需要这样做，请先停用或删除侦听器，然后重新添加它们。例如，
public void ref() {
// first remove all item listeners
ItemListener[] questionListeners = questions.getItemListeners();
ItemListener[] answerListeners = answers.getItemListeners();
for (ItemListener l : questionListeners) {
questions.removeItemListener(l);
}
for (ItemListener l : answerListeners) {
answers.removeItemListener(l);
}
// change state
questions.removeAllItems();
answers.removeAllItems();
// re-add all listeners
for (ItemListener l : questionListeners) {
questions.addItemListener(l);
}
for (ItemListener l : answerListeners) {
answers.addItemListener(l);
}
...