Question

首先，我在JFrame中调用了面板。一切正常。

现在，我想从另一个类中调用面板，以在选择其中一个面板之后切换到同一JFrame中的不同面板。我发生的问题如下：

JFrame不会以任何方式响应我对面板设置的更改。无论何时在Panel类内部调整大小，或者在JFrame类中调整大小。

面板总是像Flowlayout一样扩展到与JFrame相同的大小。但是，尝试更改布局既无济于事，也无济于事，因为Panel之前曾工作过（当在JFrame内而不是在单独的类中编码时）。

如何以这种方式修复代码，以便我可以调整面板并使JFrame识别这些更改？我目前正在使用Eclipse和NetBeans。在任何一个都不起作用。

主要：

package calculatorXtreme;

import javax.swing.JFrame;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JMenu;

public class Main {

    public static void main(String[] args) {
        Interface interface1 =new Interface();
        interface1.show();
    }

}

面板：

package calculatorXtreme;

import java.awt.Color;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JButton;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;

public class PannelDez extends JPanel {
    JLabel text = new JLabel();
    JButton delete = new JButton();
    JButton zero = new JButton();
    JButton eins = new JButton();
    JButton zwei = new JButton();
    JButton drei = new JButton();
    JButton vier = new JButton();
    JButton fuenf = new JButton();
    JButton sechs = new JButton();
    JButton sieben = new JButton();
    JButton acht = new JButton();
    JButton neun = new JButton();
    JButton addieren = new JButton();
    JButton subtrahieren = new JButton();
    JButton multiplizieren = new JButton();
    JButton dividieren = new JButton();
    JButton ergebnis = new JButton();
    JTextField anzeige = new JTextField();
    String erg = "";
    int temp1;
    RechnerInt interfaceRechner = new RechnerInt();

    public PannelDez() {

        //Panel

        this.setSize(400, 500);
        anzeige.setBounds(125,100, 200, 50);
        anzeige.setSize(200, 50);
        anzeige.setEditable(false);
        anzeige.setText(erg);
        this.add(anzeige);


        //Buttons 

        delete.setText("C");
        zero.setText("0");
        eins.setText("1");
        zwei.setText("2");
        drei.setText("3");
        vier.setText("4");
        fuenf.setText("5");
        sechs.setText("6");
        sieben.setText("7");
        acht.setText("8");
        neun.setText("9");
        addieren.setText("+");
        subtrahieren.setText("-");
        multiplizieren.setText("*");
        dividieren.setText("/");
        ergebnis.setText("=");



        this.add(delete);
        this.add(zero);
        this.add(eins);
        this.add(zwei);
        this.add(drei);
        this.add(vier);
        this.add(fuenf);
        this.add(sechs);
        this.add(sieben);
        this.add(acht);
        this.add(neun);
        this.add(addieren);
        this.add(subtrahieren);
        this.add(multiplizieren);
        this.add(dividieren);
        this.add(ergebnis);

        delete.addActionListener(new ListenDelete());
        zero.addActionListener(new ListenZero());
        eins.addActionListener(new ListenEins());
        zwei.addActionListener(new ListenZwei());
        drei.addActionListener(new ListenDrei());
        vier.addActionListener(new ListenVier());
        fuenf.addActionListener(new ListenFuenf());
        sechs.addActionListener(new ListenSechs());
        sieben.addActionListener(new ListenSieben());
        acht.addActionListener(new ListenAcht());
        neun.addActionListener(new ListenNeun());
        addieren.addActionListener(new ListenAddieren());
        subtrahieren.addActionListener(new ListenSubtrahieren());
        multiplizieren.addActionListener(new ListenMultiplizieren());
        dividieren.addActionListener(new ListenDividieren());
        ergebnis.addActionListener(new ListenErgebnis());

        /* JPanel panel2 = new JPanel();
        panel2.setLayout(new FlowLayout());  */

    }

    public void resizeButtons()
    {
        delete.setBounds(225, 350, 50, 50);
        zero.setBounds(175, 350,50,50);
        eins.setBounds(125, 300,50,50);
        zwei.setBounds(175, 300,50,50);
        drei.setBounds(225, 300,50,50);
        vier.setBounds(125, 250,50,50);
        fuenf.setBounds(175, 250,50,50);
        sechs.setBounds(225, 250,50,50);
        sieben.setBounds(125, 200,50,50);
        acht.setBounds(175, 200,50,50);
        neun.setBounds(225, 200,50,50);
        addieren.setBounds(275, 300,50,50);
        subtrahieren.setBounds(275, 250,50,50);
        multiplizieren.setBounds(275, 200,50,50);
        dividieren.setBounds(275, 150,50,50);
        ergebnis.setBounds(275, 350,50,50);
    }

    class ListenDelete implements ActionListener {
        public void actionPerformed (ActionEvent e) {
            interfaceRechner.operators.clear();
            interfaceRechner.numbers.clear();
            interfaceRechner.numbersInt.clear();
            anzeige.setText("");
        }
    }
    class ListenZero implements ActionListener {
        public void actionPerformed (ActionEvent e) {
            erg = anzeige.getText();
            anzeige.setText(erg + "0");
            erg = anzeige.getText();
        }
    }
    class ListenEins implements ActionListener {
        public void actionPerformed (ActionEvent e) {
            erg = anzeige.getText();
            anzeige.setText(erg + "1");
            erg = anzeige.getText();
            return;
        }
    }
    class ListenZwei implements ActionListener {
        public void actionPerformed (ActionEvent e) {
            erg = anzeige.getText();
            anzeige.setText(erg + "2");
            erg = anzeige.getText();
        }
    }
    class ListenDrei implements ActionListener {
        public void actionPerformed (ActionEvent e) {
            erg = anzeige.getText();
            anzeige.setText(erg + "3");
            erg = anzeige.getText();
        }
    }
    class ListenVier implements ActionListener {
        public void actionPerformed (ActionEvent e) {
            erg = anzeige.getText();
            anzeige.setText(erg + "4");
            erg = anzeige.getText();
        }
    }
    class ListenFuenf implements ActionListener {
        public void actionPerformed (ActionEvent e) {
            erg = anzeige.getText();
            anzeige.setText(erg + "5");
            erg = anzeige.getText();
        }
    }
    class ListenSechs implements ActionListener {
        public void actionPerformed (ActionEvent e) {
            erg = anzeige.getText();
            anzeige.setText(erg + "6");
            erg = anzeige.getText();
        }
    }
    class ListenSieben implements ActionListener {
        public void actionPerformed (ActionEvent e) {
            erg = anzeige.getText();
            anzeige.setText(erg + "7");
            erg = anzeige.getText();
        }
    }
    class ListenAcht implements ActionListener {
        public void actionPerformed (ActionEvent e) {
            erg = anzeige.getText();
            anzeige.setText(erg + "8");
            erg = anzeige.getText();
        }
    }
    class ListenNeun implements ActionListener {
    public void actionPerformed (ActionEvent e) {
            erg = anzeige.getText();
            anzeige.setText(erg + "9");
            erg = anzeige.getText();
        }
    }
    class ListenAddieren implements ActionListener {
    public void actionPerformed (ActionEvent e) {
            erg = anzeige.getText();
            interfaceRechner.addNumber(Integer.valueOf(erg));
            interfaceRechner.addOperators("+");
            anzeige.setText("");
            erg = null;
        }
    }
    class ListenSubtrahieren implements ActionListener {

        public void actionPerformed (ActionEvent e) {
                erg = anzeige.getText();
                interfaceRechner.addNumber(Integer.valueOf(erg));
                interfaceRechner.addOperators("-");
                anzeige.setText("");
                erg = null;
            }
        }
    class ListenMultiplizieren implements ActionListener {
        public void actionPerformed (ActionEvent e) {
                erg = anzeige.getText();
                interfaceRechner.addNumber(Integer.valueOf(erg));
                interfaceRechner.addOperators("*");
                anzeige.setText("");
                erg = null;
            }
        }
    class ListenDividieren implements ActionListener {
        public void actionPerformed (ActionEvent e) {
                erg = anzeige.getText();
                interfaceRechner.addNumber(Integer.valueOf(erg));
                interfaceRechner.addOperators("/");
                anzeige.setText("");
                erg = null;
            }
        }
    class ListenErgebnis implements ActionListener {
        public void actionPerformed (ActionEvent e) {
                erg = anzeige.getText();
                interfaceRechner.addNumber(Integer.valueOf(erg));
                interfaceRechner.addOperators("=");
                anzeige.setText(""+interfaceRechner.berechneInt());

            }
        }

}

JFrame：

package calculatorXtreme;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.plaf.ColorUIResource;
import javax.swing.JButton;
import java.awt.BorderLayout;
import java.awt.Container;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import java.awt.Color;
import java.awt.FlowLayout;
import java.awt.Frame;
import java.awt.Dimension;


public class Interface extends JFrame  {

public Interface(){

// PanelAdden

PannelDez panel2 = new PannelDez();
//panel2.setSize(400, 500);
this.setSize(700, 800);
panel2.setSize(300, 200);
this.setVisible(true);
this.setResizable(false);
panel2.setSize(400, 500);
panel2.setBounds(0, 0, 400, 500);
panel2.resizeButtons();
this.add(panel2);

// Menüleiste

JMenuBar jmb = new JMenuBar();
this.setJMenuBar(jmb);
JMenu file = new JMenu("Option");
jmb.add(file);
JMenuItem dez = new JMenuItem("Dezimal-Rechner");
file.add(dez);
JMenuItem hex = new JMenuItem("Hex-Rechner");
file.add(hex);
this.setVisible(true);


    }

}

RechnerInt：

package calculatorXtreme;

import java.util.ArrayList;
import java.util.List;

public class RechnerInt {
    List<String> numbers = new ArrayList<>();
    List<String> operators = new ArrayList<>();
    List<Double> numbersDouble = new ArrayList<>();
    List<Integer> numbersInt = new ArrayList<>();
    double zahl1, zahl2, ergebnis;
    String op;
    boolean abbruch = true;

    public double rechnen(String op, double zahl1, double zahl2)

    {

        switch (op) {
        case "+":
            ergebnis = zahl1 + zahl2;
            return ergebnis;
        case "-":
            ergebnis = zahl1 - zahl2;
            return ergebnis;
        case "/":
            ergebnis = zahl1 / zahl2;
            return ergebnis;
        case "*":
            ergebnis = zahl1 * zahl2;
            return ergebnis;
        }
        return ergebnis;
    }

    public double meineNemesis() {

        zahl1 = numbersDouble.get(0);

        for (int i = 1; i <= numbersDouble.size(); i++)

        {
            op = operators.get(i - 1);

            if (op.equals("=")) {
                return zahl1;
            }
            zahl2 = numbersDouble.get(i);
            zahl1 = rechnen(op, zahl1, zahl2);
        }
        return -80085;
    }

    public int berechneInt() 
    {
        zahl1 = numbersInt.get(0);

        for (int i = 1; i <= numbersInt.size(); i++)

        {
            op = operators.get(i - 1);

            if (op.equals("=")) {
                return (int)zahl1;
            }
            zahl2 = numbersInt.get(i);
            zahl1 = rechnen(op, zahl1, zahl2);
        }
        return -80085 ;
    }


    public void addNumber(int i) 
    {
        numbersInt.add(i);
    }

    public void addOperators(String op)
    {
        operators.add(op);
        }

}

非常感谢您

Answer 1

您的问题来自未将JFrame和JPanel的布局都设置为1. Set rs1 = CurrentDb.OpenRecordset("tblOPCEPLTB") 2. Set rs = CurrentDb.OpenRecordset("SELECT * FROM tblOPCEPLTB")，这样null才会生效。在不以这种方式显式设置布局的情况下，JPanel将盲目使用其默认的FlowLayout，而JFrame（实际上是contentPane）将盲目使用其默认的BorderLayout

因此需要进行以下更改：

setBounds(...)

class PannelDez extends JPanel {
    // .....

    public PannelDez() {
        // Panel
        setLayout(null);

        // ....
    }

    // ....
}

但是，我重申了我之前所说的话：

尽管null布局和setBounds（）似乎是Swing新手创建复杂GUI的最简单和最佳方法，但您创建的Swing GUI越多，使用它们时将遇到的困难就越严重。当GUI调整大小时，它们不会重新调整组件的大小；它们是需要增强或维护的皇家女巫；放置在滚动窗格中时，它们会完全失败；在所有平台或与原始分辨率不同的屏幕分辨率下查看时，它们看起来都是令人毛骨悚然的

同样，解决此问题的更好方法是学习和使用布局管理器。例如，您正在创建一个计算器，这很适合使用两个JPanel，一个用于保存使用GridLayout的按钮以创建按钮网格，另一个用于使用BorderLayout来保存上述JPanel在其中心位置，并将JTextField保持在最高位置class Interface extends JFrame { public Interface() { setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); setLayout(null); // PanelAdden // ..... } // .......... }。还要注意，最好尽力避免代码重复，就像我们在所有ActionListener中看到的那样。您只需要两个 ActionListeners-每个数字按钮一个，每个操作一个。

下面的代码创建一个如上所述的Swing GUI，一个带有嵌套的JPanels，一个外部使用BorderLayout，内部使用GridLayout（0，4），代表可变的行数（0）和4列。 GUI的图像：

和代码：

import java.awt.BorderLayout; 导入java.awt.Font; 导入java.awt.GridLayout; 导入java.awt.event.ActionEvent; 导入java.awt.event.ActionListener; 导入javax.swing。*;

BorderLayout.PAGE_START

@SuppressWarnings("serial")
public class FooGui02 extends JPanel {
    private static final Font BUTTON_FONT = new Font(Font.SANS_SERIF, Font.BOLD, 36);
    private static final Font ANZEIGE_FONT = new Font(Font.SANS_SERIF, Font.PLAIN, 24);
    private JTextField anzeige = new JTextField(10);
    RechnerInt interfaceRechner = new RechnerInt();

    public FooGui02() {
        anzeige.setFont(ANZEIGE_FONT);
        // anzeige.setEnabled(false);
        anzeige.setBackground(null);
        anzeige.setFocusable(false); // user can't interact with this

        // create a grid of 4 columns and variable rows:
        JPanel btnPanel = new JPanel(new GridLayout(0, 4));

        // create first row
        // add 3 blank JLabels
        for (int i = 0; i < 3; i++) {
            btnPanel.add(new JLabel());
        }
        btnPanel.add(createOperationButton(Operation.DIVISION));

        // second row
        btnPanel.add(createNumberButton(7));
        btnPanel.add(createNumberButton(8));
        btnPanel.add(createNumberButton(9));
        btnPanel.add(createOperationButton(Operation.MULTIPLICATION));

        // third row
        btnPanel.add(createNumberButton(4));
        btnPanel.add(createNumberButton(5));
        btnPanel.add(createNumberButton(6));
        btnPanel.add(createOperationButton(Operation.SUBTRACTION));

        // forth row
        btnPanel.add(createNumberButton(1));
        btnPanel.add(createNumberButton(2));
        btnPanel.add(createNumberButton(3));
        btnPanel.add(createOperationButton(Operation.ADDITION));

        // fifth row
        btnPanel.add(new JLabel());
        btnPanel.add(createNumberButton(0));
        btnPanel.add(createOperationButton(Operation.CLEAR));
        btnPanel.add(createOperationButton(Operation.EQUALS));

        setLayout(new BorderLayout());
        add(anzeige, BorderLayout.PAGE_START);
        add(btnPanel);
    }

    private JButton createOperationButton(Operation operation) {
        JButton button = new JButton(operation.getText());
        button.addActionListener(new OperationListener(operation));
        button.setFont(BUTTON_FONT);
        return button;
    }

    private JButton createNumberButton(int number) {
        JButton button = new JButton("" + number);
        button.addActionListener(new NumberListener(number));
        button.setFont(BUTTON_FONT);
        return button;
    }

    private class OperationListener implements ActionListener {
        private Operation operation;

        public OperationListener(Operation operation) {
            this.operation = operation;
        }

        @Override
        public void actionPerformed(ActionEvent e) {
            String text = anzeige.getText();

            switch (operation) {
            case CLEAR:
                interfaceRechner.operators.clear();
                interfaceRechner.numbers.clear();
                interfaceRechner.numbersInt.clear();
                anzeige.setText("");
                break;

            case ADDITION:
                interfaceRechner.addNumber(Integer.valueOf(text));
                interfaceRechner.addOperators("+");
                anzeige.setText("");
                break;

            case SUBTRACTION:
                interfaceRechner.addNumber(Integer.valueOf(text));
                interfaceRechner.addOperators("-");
                anzeige.setText("");
                break;

            case MULTIPLICATION:
                interfaceRechner.addNumber(Integer.valueOf(text));
                interfaceRechner.addOperators("*");
                anzeige.setText("");
                break;

            case DIVISION:
                interfaceRechner.addNumber(Integer.valueOf(text));
                interfaceRechner.addOperators("/");
                anzeige.setText("");
                break;

            case EQUALS:
                interfaceRechner.addNumber(Integer.valueOf(text));
                interfaceRechner.addOperators("=");
                anzeige.setText("" + interfaceRechner.berechneInt());
                interfaceRechner.operators.clear();
                interfaceRechner.numbers.clear();
                interfaceRechner.numbersInt.clear();
                break;

            default:
                break;
            }
        }
    }

    private class NumberListener implements ActionListener {
        private int number;

        public NumberListener(int number) {
            this.number = number;
        }

        @Override
        public void actionPerformed(ActionEvent e) {
            String text = anzeige.getText();
            text += number;
            anzeige.setText(text);
        }
    }

    private static void createAndShowGui() {
        FooGui02 mainPanel = new FooGui02();

        JFrame frame = new JFrame("Calculator");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.getContentPane().add(mainPanel);
        frame.pack();
        frame.setResizable(false);
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(() -> createAndShowGui());
    }
}

JPanel无法适应任何更改

1 个答案: