Question

这是我到目前为止的代码。

    import java.util.*;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JRadioButton;
import javax.swing.Action;
import javax.swing.BoxLayout;
import javax.swing.JButton;
import java.awt.event.*;



import java.awt.Component; 


public class MAIN {
    public static void main(String[] args) {

        String grade = null, sub = null;
        int x = 0;
        ALevel[] array = new ALevel[3];

        for (x = 0; x < 3; x++) {
        JFrame frame = new JFrame("COURSE CHECKER");
        frame.setVisible(true);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setSize(500, 500);
        frame.setLocation(430, 100);

        JPanel panel = new JPanel();
        panel.setLayout(new BoxLayout(panel, BoxLayout.Y_AXIS)); 

        frame.add(panel);

        JLabel lbl = new JLabel("Select your subject(s):");
        lbl.setAlignmentX(Component.CENTER_ALIGNMENT);
        //lbl.setVisible(true); 

        panel.add(lbl);

        //define items in a String array
        String[] choices = { "MATHEMATICS", "FURTHER MATHEMATICS", "ACCOUNTING", "ECONOMICS",
                             "MANAGEMENT OF BUSINESS", "COMPUTER STUDIES", "PHYSICS", "CHEMISTRY",
                             "BIOLOGY", "DESIGN & TECHNOLOGY", "GEOGRAPHY"};


        //create combobox/dropdown with the fixed array
        final JComboBox<String> cb = new JComboBox<String>(choices);

        cb.setMaximumSize(cb.getPreferredSize()); 
        cb.setAlignmentX(Component.CENTER_ALIGNMENT);
        //cb.setVisible(true); 
        panel.add(cb);

        frame.setVisible(true); 

        array[x] = new ALevel(grade, sub);
        array[x].gradecheck(sub, array[x].getaGrade());
    }

        cb.addActionListener(new ActionListener(){
            public void actionPerformed(Action e){
                String data = "Subject Selected: " + cb.getItemAt(cb.getSelectedIndex());
                    lbl.setText(data);
            }

        };

        JLabel lbl1 = new JLabel("Select your grades");
        lbl1.setAlignmentX(Component.CENTER_ALIGNMENT);
        //lbl.setVisible(true); 

        panel.add(lbl1);

        //define items in a String array
        String[] choices1 = { "A", "B", "C", "D", "E"};

        //create combobox/dropdown with the fixed array
        final JComboBox<String> cb1 = new JComboBox<String>(choices1);

        cb1.setMaximumSize(cb1.getPreferredSize()); 
        cb1.setAlignmentX(Component.CENTER_ALIGNMENT);
        //cb.setVisible(true); 
        panel.add(cb1);

        JButton btn1 = new JButton("OK");
        btn1.setAlignmentX(Component.CENTER_ALIGNMENT);
        panel.add(btn1);

        frame.setVisible(true); 


    for (x = 0; x < 3; x++) {
        System.out.println("\nSubject: " + array[x].getaSub() + "\nGrade:" + array[x].getaGrade());
    }
    System.out.println("\nPoint: " + array[0].getaScore());



        //
        Scanner input = new Scanner(System.in);
        String grade = null, sub = null;
        int x = 0;
        ALevel[] array = new ALevel[3];

        for (x = 0; x < 3; x++) {
            System.out.print("Enter subject: ");
            sub = input.nextLine();
            System.out.print("Enter grade: ");
            grade = input.nextLine();

            array[x] = new ALevel(grade, sub);
            array[x].gradecheck(sub, array[x].getaGrade());
        }

        for (x = 0; x < 3; x++) {
            System.out.println("\nSubject: " + array[x].getaSub() + "\nGrade:" + array[x].getaGrade());
        }
        System.out.println("\nPoint: " + array[0].getaScore());
        System.out.println("You are eligible for: ");

        for (x = 0; x < 3; x++) {
            if (array[x].getSubjects() == 3) {
                if (array[x].isMathcheck() == true && array[x].getSubscoreE() >= 3 && array[x].getaScore() >= 200) {
                    array[x].SCI();
                }
                if (array[x].getSubscoreE() >= 3 && array[x].getaScore() >= 200) {
                    array[x].SOB();
                }
                if (array[x].isMathcheck() == true && array[x].getSubscoreS() >= 2 && array[x].getaScore() >= 240) {
                    array[x].CEPA();
                }
                if (array[x].isMathcheck() == true && array[x].isPhyscheck() == true && array[x].getSubscoreS() >= 2
                        && array[x].getaScore() >= 220) {
                    array[x].E3PA();
                }
                if (array[x].isMathcheck() == true && array[x].isPhyscheck() == true && array[x].isChemcheck() == true
                        && array[x].getaScore() >= 240) {
                    array[x].PCEPA();
                }
                if (array[x].isMathcheck() == true && array[x].isPhyscheck() == true && array[x].getSubscoreS() >= 2
                        && array[x].getaScore() >= 240) {
                    array[x].MEPA();
                }
            }
            if (array[x].getSubjects() == 2) {
                if (array[x].isMathcheck() == true && array[x].getSubscoreE() >= 2 && array[x].getaScore() >= 180) {
                    array[x].SCI();
                }
                if (array[x].getSubscoreE() >= 2 && array[x].getaScore() >= 180) {
                    array[x].SOB();
                }
                if (array[x].isMathcheck() == true && array[x].isPhyscheck() == true && array[x].getaScore() >= 180) {
                    array[x].E3PA();
                }
                if (array[x].isMathcheck() == true && array[x].isPhyscheck() == true && array[x].getaScore() >= 180) {
                    array[x].MEPA();
                }
            }
            if (array[x].getaScore() < 180) {
                System.out.print("None");
            }
            System.exit(0);
        }//
    }
}

编码在没有组合框的情况下运行良好，数据在控制台选项卡中显示为dsiplayed。

我希望通过从组合框中选择数据而不是输入输入来更轻松。那么，我如何从组合框中显示所选项目？

Answer 1

您需要获得＆＃34;所选项目＆＃34;来自组合框。

然后，您可以使用从组合框中抓取的数据更新标签，文本区域或其他任何内容。

JComboBox cb = (JComboBox)e.getSource();
String myName = (String)cb.getSelectedItem();
updateLabel(myName);

请注意cb.getSelectedItem()。这实际上是从组合框中获取数据的。

这里有一个很好的资源，有关于使用Java组合框的更多信息：https://docs.oracle.com/javase/tutorial/uiswing/components/combobox.html

如何显示来自combobox java的所选项目？

1 个答案: