嘗試將JComboBox實現到程序中-Java

Question

這是我的第一篇文章！

我正在嘗試將TutCombo程序中制作的組合框實現為ExamGradesGUI + ExamGrades之一。 正如您在TutCombo程序中看到的那樣，有一個'String subjectUnitTxt'。 理想情況下，我希望以此替換ExamGradesGUI程序中的“ subjectUnitTxt”，但具有組合框的功能，並且能夠與firstName，lastName和examMark一起保存到文件中。 如果有人可以告訴我該怎么做，那將很棒。 抱歉，如果我添加了太多代碼。 謝謝

Answer 1

我通過對您的代碼進行一些小的更改來使它起作用（請參閱附件的代碼）。 搜索“ unitCombo”。

 import java.awt.Color; import java.awt.GridLayout; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; 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.swing.JTextField; public class ExamGradesGUI { public static void main(String[] args) { new ExamGradesGUI(); } String[] firstName = new String[20]; String[] lastName = new String[20]; String[] subjectUnit = new String[20]; double[] examMark = new double[20]; private JLabel firstNameLbl, lastNameLbl, unitLbl, markLbl; private JTextField firstNameTxt, lastNameTxt, subjectUnitTxt, examMarkTxt; private JComboBox<String> unitCombo; private JButton btnClear, btnSave, btnOpen, btnExit; private JPanel panel; private JFrame frame; public ExamGradesGUI(){ buildFrame(); buildFields(); buildButtons(); frame.setVisible(true); frame.add(panel); } public void buildFrame(){ frame = new JFrame("GradeEnter"); frame.setSize(650,450); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); panel = new JPanel(); panel.setLayout(null); panel.setBackground(Color.white); } public void buildFields(){ // Labels, User Input + Location firstNameTxt = new JTextField(10); firstNameTxt.setBounds(180, 80, 150, 20); panel.add(firstNameTxt); String str = firstNameTxt.getText(); if(str.matches("[-a-zA-Z]*")) { } else { JOptionPane.showMessageDialog(null, "Please enter amount donating"); } lastNameTxt = new JTextField(10); lastNameTxt.setBounds(180, 110, 150, 20); panel.add(lastNameTxt); subjectUnitTxt = new JTextField(10); String[] courses = {"Computing","Forensic","Business"}; unitCombo = new JComboBox<String>(courses); //subjectUnitTxt.setBounds(180, 140, 150, 20); //panel.add(subjectUnitTxt); unitCombo.setBounds(180, 140, 150, 20); panel.add(unitCombo); // IF HAVE TIME: Turn Combo Box into GUI - Refer to testgui.java examMarkTxt = new JTextField(10); examMarkTxt.setBounds(180, 170, 150, 20); panel.add(examMarkTxt); firstNameLbl = new JLabel("First Name:"); firstNameLbl.setBounds(70, 80, 100, 20); panel.add (firstNameLbl); lastNameLbl = new JLabel("Last Name:"); lastNameLbl.setBounds(70, 110, 100, 20); panel.add (lastNameLbl); unitLbl = new JLabel("Unit:"); unitLbl.setBounds(70, 140, 100, 20); panel.add (unitLbl); markLbl = new JLabel("Mark:"); markLbl.setBounds(70, 170, 100, 20); panel.add (markLbl); } public void buildButtons() { btnClear = new JButton ("Reset Fields"); btnClear.setBounds(55, 220, 110, 20); btnClear.addActionListener(new ClearButtonListener()); panel.add (btnClear); btnSave = new JButton ("Save"); btnSave.setBounds(155, 220, 70, 20); btnSave.addActionListener(new SaveButton()); panel.add (btnSave); btnOpen = new JButton ("Open 'GradeEnter.txt' "); btnOpen.setBounds(90, 250, 200, 20); btnOpen.addActionListener(new OpenButton()); panel.add (btnOpen); btnExit = new JButton ("Exit"); btnExit.setBounds(255, 220, 70, 20); btnExit.addActionListener(new ExitButton()); panel.add (btnExit); } public void setText() { firstNameTxt.setText(""); lastNameTxt.setText(""); subjectUnitTxt.setText(""); examMarkTxt.setText(""); } public void getText() { int i = 0; i++; firstName[i] = firstNameTxt.getText(); lastName[i] = lastNameTxt.getText(); subjectUnit[i] = unitCombo.getItemAt(unitCombo.getSelectedIndex()); examMark[i] = Double.parseDouble(examMarkTxt.getText()); } private class ClearButtonListener implements ActionListener { public void actionPerformed (ActionEvent e) { setText(); } } private class SaveButton implements ActionListener { public void actionPerformed(ActionEvent e) { getText(); setText(); ExamGrades save = new ExamGrades(); save.fileOpen(); save.addRecords(firstName, lastName, subjectUnit, examMark); JOptionPane.showMessageDialog(null, "Entry Saved!"); save.fileClose(); } } private class OpenButton implements ActionListener { public void actionPerformed(ActionEvent e) { try { JOptionPane.showMessageDialog(null, "'GradeEnter.txt' opening in Java!"); Thread.sleep(2); // Adds a 2 second delay so user can read dialog message Runtime.getRuntime().exec("eclipse GradeEnter.txt" ); } catch (Exception NoFileFound) { System.out.println("Couldn't open or find the file."); } } } class ExitButton implements ActionListener{ public void actionPerformed(ActionEvent e) { int n = JOptionPane.showConfirmDialog(frame, "Are you sure you want to exit?", "Exit?", JOptionPane.YES_NO_OPTION); if(n == JOptionPane.YES_OPTION){ System.exit(0); } } } }