我正在尝试创建一个带有 JLabel 的框架。我已成功将其添加到框架中，但文本显示在狭窄的列中，而不是占用窗口中的更多空间。我该如何解决？我尝试使用 html 但没有成功。
编辑:介绍面板是我遇到问题的面板。
import java.awt.BorderLayout;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Insets;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.text.DecimalFormat;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;
public class Window implements ActionListener{
JFrame frame = new JFrame("Loan Program");
JFrame intro = new JFrame("Welcome To The Loan Program!");
JPanel panel = new JPanel(new GridBagLayout());
JPanel panel2 = new JPanel(new GridBagLayout());
JPanel panel3 = new JPanel(new GridBagLayout());
JPanel descriptionPanel = new JPanel(new GridBagLayout());
JPanel descriptionPanel1 = new JPanel(new GridBagLayout());
GridBagConstraints g = new GridBagConstraints();
JButton calculate;
JButton cancel;
JButton reset;
JButton introOk;
JLabel loanAmount;
JLabel loanInterest;
JLabel loanPeriod;
JLabel monthlyRepayment;
JLabel introLabel;
JTextField laField;
JTextField liField;
JTextField lpField;
JTextField mrField;
DecimalFormat df = new DecimalFormat("#.##");
public Window() {
g.insets = new Insets(10, 10, 20, 10); //For the spacing between elements
//Initalizing components
introLabel = new JLabel();
introOk = new JButton("Ok");
//Setting up text for intro panel
String text = "<html><h1 align='center'>Loan Program 1.0</h1>";
text = text + "This program lets you calculate the various aspects of loans <br />";
text = text + "If you are leaving a field empty then use 0 for its place <br />";
text = text + "<h1 align='center'>Text Fields To Enter</h1>";
text = text + "Monthly Payment: Enter values for: Loan Period, Loan Amount, and Loan Interest. Enter 0 for Monthly Payment. <br />";
text = text + "Loan Period: Enter Values for: Loan Amount, Loan Interest, and Monthly Payment. Enter 0 for Loan Period. <br />";
//Setting text to the label
introLabel.setText(text);
//Positioning introLabel
descriptionPanel.add(introLabel, g);
//Positioning button
descriptionPanel1.add(introOk, g);
//Actionlistener for buttont to dipose current frame.
introOk.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
intro.dispose();
}
});
intro.add(descriptionPanel);
intro.add(descriptionPanel1, BorderLayout.SOUTH);
//Initializing buttons here and adding them to panel
calculate = new JButton("Calculate");
reset = new JButton("Reset");
cancel = new JButton("Cancel");
panel.add(calculate, g);
panel.add(reset, g);
panel.add(cancel, g);
//Adding the Actionlistener for buttons
calculate.addActionListener(this);
reset.addActionListener(this);
cancel.addActionListener(this);
//Initializing the labels
loanAmount = new JLabel("Loan Amount:");
loanInterest = new JLabel("Loan Interest:");
loanPeriod = new JLabel("Loan Period:");
monthlyRepayment = new JLabel("Monthly Payment:");
//Positioning loanAmount label
g.gridx = 0;
g.gridy = 0;
panel2.add(loanAmount, g);
//Positioning loanInterest label
g.gridx = 0;
g.gridy = 2;
panel2.add(loanInterest, g);
//Positioning loanPeriod label
g.gridx = 0;
g.gridy = 3;
panel2.add(loanPeriod, g);
//Positioning monthlyRepayment label
g.gridx = 0;
g.gridy = 4;
panel2.add(monthlyRepayment, g);
//Initializing the text fields
laField = new JTextField("", 20);
liField = new JTextField("", 20);
lpField = new JTextField("", 20);
mrField = new JTextField("", 20);
//Positioning laField
g.gridx = 1;
g.gridy = 0;
panel2.add(laField, g);
//Positioning liField
g.gridx = 1;
g.gridy = 2;
panel2.add(liField, g);
//Positioning lpField
g.gridx = 1;
g.gridy = 3;
panel2.add(lpField, g);
//Positioning mrField
g.gridx = 1;
g.gridy = 4;
panel2.add(mrField, g);
//Adding panels to the frame using boarderlayout
frame.add(panel, BorderLayout.SOUTH);
frame.add(panel2, BorderLayout.WEST);
// Creating the window
frame.setSize(500, 500);
frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
//popup window for intro
intro.setSize(500, 500);
intro.setVisible(true);
intro.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
@Override
public void actionPerformed(ActionEvent e) {
Object o = e.getSource();
if(o == cancel) {
//Initializing components for the window
JFrame frame1 = new JFrame("Are you sure?");
JPanel panel = new JPanel(new GridBagLayout());
JPanel panel2 = new JPanel(new GridBagLayout());
JLabel label = new JLabel("Are you sure you want to exit?");
JButton yes = new JButton("Yes");
JButton no = new JButton("No");
//Positioning Label
g.gridx = 0;
g.gridy = 0;
panel.add(label, g);
//Positioning yes button
g.gridx = 0;
g.gridy = 0;
g.gridwidth = 1;
panel2.add(yes, g);
//Positioning no button
g.gridx = 1;
g.gridy = 0;
panel2.add(no, g);
//Action to close program when yes is clicked
yes.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
System.exit(0);
}
});
//Action to close current window if no is clicked
no.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
frame1.dispose();
}
});
//Adding the panels to frame with borderlayout
frame1.add(panel, BorderLayout.NORTH);
frame1.add(panel2, BorderLayout.SOUTH);
//Setting up frame
frame1.setSize(300, 300);
frame1.setVisible(true);;
frame1.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
//Adding actionListener once again for second level of menu
//No to close the current window
Object b = e.getSource();
if(b == no) {
System.out.println("heres");
frame1.dispose();
}
//Yes to close the program completely
if(b == yes) {
System.exit(0);
}
}
//New instance of window to reset it
if(o == reset) {
frame.dispose();
new Window();
}
//Calculate buttons actions
if(o == calculate) {
//Test values to see if they are being passed
System.out.println(laField.getText() + "\n" + liField.getText() + "/n" + lpField.getText() + "\n" + mrField.getText());
//If statement for monthly payment with the correct fields filled out
if(laField.getText() != null && liField.getText() != null && lpField.getText() != null && mrField.getText() == "0") {
//Strings and double and ints to convert from text field number.
String sRate, sMonths, sPrincipal;
sRate = liField.getText();
sMonths = lpField.getText();
sPrincipal = laField.getText();
double rate = Double.parseDouble(sRate);
int months = Integer.parseInt(sMonths);
double principal = Double.parseDouble(sPrincipal);
//Setting up components for new window
JFrame frame = new JFrame("Monthly Payment");
JPanel panel = new JPanel(new GridBagLayout());
JPanel panel2 = new JPanel(new GridBagLayout());
JLabel label = new JLabel("The monthly payment is: " + df.format(calculateMonthlyRepayment(rate, months, principal)));
JButton button = new JButton("Ok");
//Action listener for okay button to just close current frame.
button.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
frame.dispose();
}
});
//Padding for element
g.insets = new Insets(5, 5, 5, 5);
//Adding components to panel
panel.add(label, g);
panel2.add(button, g);
//Adding panels to frame
frame.add(panel, BorderLayout.CENTER);
frame.add(panel2, BorderLayout.SOUTH);
//Intializing frame
frame.setSize(300, 300);
frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
//If statement for period calculation checks to see proper fields filled
if(mrField.getText() != null && liField.getText() != null && laField.getText() != null && lpField.getText() == "0"); {
//String and doubles to convert to numbers from text box
String sMonthlyPayment, sloanAmount, sinterestRate;
sMonthlyPayment = mrField.getText();
sloanAmount = laField.getText();
sinterestRate = liField.getText();
double monthlyPayment = Double.parseDouble(sMonthlyPayment);
double loanAmount = Double.parseDouble(sloanAmount);
double interestRate = Double.parseDouble(sinterestRate);
//Initializing the components
JFrame frame = new JFrame("Total Loan Period");
JPanel panel = new JPanel(new GridBagLayout());
JPanel panel2 = new JPanel(new GridBagLayout());
JLabel label = new JLabel("Total number of periods is : " + calculatePeriod(monthlyPayment, interestRate, loanAmount));
JButton button = new JButton("Ok");
//Button listener to close current frame
button.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
frame.dispose();
}
});
//Padding for the components
g.insets = new Insets(5, 5, 5, 5);
//Adding componeents to panel with gridbag
panel.add(label, g);
panel2.add(button, g);
//Adding panels to frame
frame.add(panel, BorderLayout.CENTER);
frame.add(panel2, BorderLayout.SOUTH);
//Initializing the frame
frame.setSize(300, 300);
frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
}
}
public double calculateMonthlyRepayment(double rate, int months, double principal) {
String input = mrField.getText();
double totalMr = Double.parseDouble(input);
double mrpayment = (rate + ((rate)/((Math.pow(1 + rate, months) - 1)))) * principal;
return mrpayment;
}
double calculatePeriod(double monthlyPayment, double interestRate, double loanAmount) {
return (Math.log(monthlyPayment) - Math.log(monthlyPayment - (loanAmount * interestRate))) / Math.log(1 + interestRate);
}
}
最佳答案
首先，建议，请尝试使用 gui 设计器，如 window builder 或 matisse。它们确实简化了您的日常工作，并限制了定义布局约束的代码的坏处。
如果您遇到布局问题以及组件不显示或未对齐，这通常是您所需的布局管理器使用错误的迹象。 stackoverflow 上有很多关于它的优秀帖子。
代码中最严重的错误是重用 GridBagConstraints，它是 bad idea因为
As you might have guessed from the above example, it is possible to reuse the same GridBagConstraints instance for multiple components, even if the components have different constraints. However, it is recommended that you do not reuse GridBagConstraints, as this can very easily lead to you introducing subtle bugs if you forget to reset the fields for each new instance.
因此，仅当每个组件的约束都相同时才尝试共享您的约束，例如标签的约束和文本字段列的另一个约束。
在狭窄的列上也存在您的错误。如果您还想为所有标签指定所需的宽度，请在标签约束上设置网格宽度。这也适用于文本字段约束。
查看 GridBagLayout Example再次，为了更好地理解其用法。
更多建议: 将您的类命名为 Window 可能会误导其他人，因为他们可能会认为自己正在使用 java.awt.window，这与您的类完全不同，并且可以进行监督，因为您只能在 import 语句中看到它。
任何 gui 元素都必须从 EDT 调用，因此使用 SwingUtilities 调用您的类，例如
SwingUtilities.invokeLater(new Runnable() {
public void run() {
new Window();
}
});
别忘了调用pack()让布局管理器根据您的约束完成其工作。
也尽量避免使用大量的框架，而是使用对话框。仅当需要将框架置于单独的上下文中时才应使用框架，就像它们彼此完全独立一样。
供您开始的示例:
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.SwingUtilities;
import java.awt.Dimension;
import java.awt.GridBagLayout;
import java.awt.BorderLayout;
import javax.swing.JPanel;
import java.awt.GridBagConstraints;
import java.awt.Insets;
import javax.swing.JTextField;
import javax.swing.JButton;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
public class GridExample extends JFrame{
public GridExample() {
initComponents();
pack();
setTitle("GridExample");
setDefaultCloseOperation(EXIT_ON_CLOSE);
setLocationRelativeTo(null); //Center, could also be setLocationByPlatform(true);
}
@Override
public Dimension preferredSize() {
return new Dimension(500,300);
}
private void initComponents() {
getContentPane().setLayout(new BorderLayout(0, 0));
JPanel mainPanel = new JPanel();
getContentPane().add(mainPanel, BorderLayout.CENTER);
GridBagLayout gbl_mainPanel = new GridBagLayout();
gbl_mainPanel.columnWidths = new int[]{0, 0, 0, 0};
gbl_mainPanel.rowHeights = new int[]{0, 0, 0, 0, 0, 0};
gbl_mainPanel.columnWeights = new double[]{0.0, 1.0, 0.0, Double.MIN_VALUE};
gbl_mainPanel.rowWeights = new double[]{0.0, 0.0, 0.0, 0.0, 0.0, Double.MIN_VALUE};
mainPanel.setLayout(gbl_mainPanel);
JLabel lblLoanAmount = new JLabel("Loan Amount:");
GridBagConstraints gbc_lblLoanAmount = new GridBagConstraints();
gbc_lblLoanAmount.fill = GridBagConstraints.HORIZONTAL;
gbc_lblLoanAmount.insets = new Insets(0, 0, 5, 5);
gbc_lblLoanAmount.gridx = 0;
gbc_lblLoanAmount.gridy = 0;
mainPanel.add(lblLoanAmount, gbc_lblLoanAmount);
txtLoanAmount = new JTextField();
GridBagConstraints gbc_txtLoanAmount = new GridBagConstraints();
gbc_txtLoanAmount.gridwidth = 2;
gbc_txtLoanAmount.insets = new Insets(0, 0, 5, 0);
gbc_txtLoanAmount.fill = GridBagConstraints.HORIZONTAL;
gbc_txtLoanAmount.gridx = 1;
gbc_txtLoanAmount.gridy = 0;
mainPanel.add(txtLoanAmount, gbc_txtLoanAmount);
txtLoanAmount.setColumns(10);
JLabel lblLoanInterest = new JLabel("Loan Interest:");
GridBagConstraints gbc_lblLoanInterest = new GridBagConstraints();
gbc_lblLoanInterest.insets = new Insets(0, 0, 5, 5);
gbc_lblLoanInterest.fill = GridBagConstraints.BOTH;
gbc_lblLoanInterest.gridx = 0;
gbc_lblLoanInterest.gridy = 1;
mainPanel.add(lblLoanInterest, gbc_lblLoanInterest);
txtLoanInterest = new JTextField();
GridBagConstraints gbc_txtLoanInterest = new GridBagConstraints();
gbc_txtLoanInterest.gridwidth = 2;
gbc_txtLoanInterest.anchor = GridBagConstraints.NORTH;
gbc_txtLoanInterest.insets = new Insets(0, 0, 5, 0);
gbc_txtLoanInterest.fill = GridBagConstraints.HORIZONTAL;
gbc_txtLoanInterest.gridx = 1;
gbc_txtLoanInterest.gridy = 1;
mainPanel.add(txtLoanInterest, gbc_txtLoanInterest);
txtLoanInterest.setColumns(10);
JLabel lblLoanPeriod = new JLabel("Loan Period:");
GridBagConstraints gbc_lblLoanPeriod = new GridBagConstraints();
gbc_lblLoanPeriod.fill = GridBagConstraints.HORIZONTAL;
gbc_lblLoanPeriod.insets = new Insets(0, 0, 5, 5);
gbc_lblLoanPeriod.gridx = 0;
gbc_lblLoanPeriod.gridy = 2;
mainPanel.add(lblLoanPeriod, gbc_lblLoanPeriod);
txtLoanPeriod = new JTextField();
GridBagConstraints gbc_txtLoanPeriod = new GridBagConstraints();
gbc_txtLoanPeriod.gridwidth = 2;
gbc_txtLoanPeriod.anchor = GridBagConstraints.NORTH;
gbc_txtLoanPeriod.insets = new Insets(0, 0, 5, 0);
gbc_txtLoanPeriod.fill = GridBagConstraints.HORIZONTAL;
gbc_txtLoanPeriod.gridx = 1;
gbc_txtLoanPeriod.gridy = 2;
mainPanel.add(txtLoanPeriod, gbc_txtLoanPeriod);
txtLoanPeriod.setColumns(10);
JLabel lblMonthlyPayment = new JLabel("Monthly Payment:");
GridBagConstraints gbc_lblMonthlyPayment = new GridBagConstraints();
gbc_lblMonthlyPayment.fill = GridBagConstraints.HORIZONTAL;
gbc_lblMonthlyPayment.insets = new Insets(0, 0, 5, 5);
gbc_lblMonthlyPayment.gridx = 0;
gbc_lblMonthlyPayment.gridy = 3;
mainPanel.add(lblMonthlyPayment, gbc_lblMonthlyPayment);
txtMonthlyPament = new JTextField();
GridBagConstraints gbc_txtMonthlyPament = new GridBagConstraints();
gbc_txtMonthlyPament.gridwidth = 2;
gbc_txtMonthlyPament.insets = new Insets(0, 0, 5, 0);
gbc_txtMonthlyPament.anchor = GridBagConstraints.NORTH;
gbc_txtMonthlyPament.fill = GridBagConstraints.HORIZONTAL;
gbc_txtMonthlyPament.gridx = 1;
gbc_txtMonthlyPament.gridy = 3;
mainPanel.add(txtMonthlyPament, gbc_txtMonthlyPament);
txtMonthlyPament.setColumns(10);
JButton btnCalculate = new JButton("Calculate");
btnCalculate.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
calculate();
}
private void calculate() {
//do the math here
txtResult.setText("Calculate pressed!");
}
});
JLabel lblResult = new JLabel("Result:");
GridBagConstraints gbc_lblResult = new GridBagConstraints();
gbc_lblResult.fill = GridBagConstraints.HORIZONTAL;
gbc_lblResult.insets = new Insets(0, 0, 0, 5);
gbc_lblResult.gridx = 0;
gbc_lblResult.gridy = 4;
mainPanel.add(lblResult, gbc_lblResult);
txtResult = new JTextField();
GridBagConstraints gbc_txtResult = new GridBagConstraints();
gbc_txtResult.insets = new Insets(0, 0, 0, 5);
gbc_txtResult.fill = GridBagConstraints.HORIZONTAL;
gbc_txtResult.gridx = 1;
gbc_txtResult.gridy = 4;
mainPanel.add(txtResult, gbc_txtResult);
txtResult.setColumns(10);
GridBagConstraints gbc_btnCalculate = new GridBagConstraints();
gbc_btnCalculate.gridx = 2;
gbc_btnCalculate.gridy = 4;
mainPanel.add(btnCalculate, gbc_btnCalculate);
}
private static final long serialVersionUID = 1L;
private JTextField txtLoanAmount;
private JTextField txtLoanInterest;
private JTextField txtLoanPeriod;
private JTextField txtMonthlyPament;
private JTextField txtResult;
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
GridExample g = new GridExample();
String text = "<html><h1 align='center'>Loan Program 1.0</h1>";
text = text + "This program lets you calculate the various aspects of loans <br />";
text = text + "If you are leaving a field empty then use 0 for its place <br />";
text = text + "<h1 align='center'>Text Fields To Enter</h1>";
text = text + "Monthly Payment: Enter values for: Loan Period, Loan Amount, and Loan Interest. Enter 0 for Monthly Payment. <br />";
text = text + "Loan Period: Enter Values for: Loan Amount, Loan Interest, and Monthly Payment. Enter 0 for Loan Period. <br />";
g.setVisible(true);
JOptionPane.showMessageDialog(g, new JLabel(text));
}
});
}
}
关于java - JLabel 文本在窄列中而不是展开，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/27009494/