按下按钮后，如何更改 JTextField 的背景颜色？

Question

我为学校项目制作贷款计算器，一旦我按下按钮，我就无法弄清楚如何更改背景颜色和黄色。如果可以的话，作为奖励，您如何更改在文本字段中输入的文本的字体大小。txtMonthlyPaymenttxtTotalPaymentComputePayment谢谢！;)import java.awt.*; //enables java GUIimport java.awt.event.*;//enables the user to respond, such as using the mouse and keyboardimport javax.swing.*;//more awt and swing imports to be associated with components / objectsimport javax.swing.border.TitledBorder; //title of the JFrame windowimport java.awt.event.ActionListener; // used to set actions for certain components / objectsimport java.awt.Color; // used to alter colour of components / objectsimport java.awt.Font; // used to change font size / stylepublic class LoanCalculator extends JFrame {//create text fields for interest rate, years, loan amount, monthly pmt and total pmtprivate JTextField txtAnnualInterestRate = new JTextField();//text fields that appear, their namesprivate JTextField txtNumberOfYears = new JTextField();private JTextField txtLoanAmount = new JTextField();private JTextField txtMonthlyPayment = new JTextField();//define the control here, then add to the panel, belowprivate JTextField txtTotalPayment = new JTextField();//create a compute payment buttonprivate JButton jbtComputeLoan = new JButton("Compute Payment"); //text appears on the buttonpublic LoanCalculator(){    //craft a panel to hold labels and text fields    JPanel p1 = new JPanel(new GridLayout(5, 2));//dimensions specified    p1.add(new JLabel("Annual Interest Rate"));    p1.add(txtAnnualInterestRate);    p1.add(new JLabel("Number of Years"));    p1.add(txtNumberOfYears);    p1.add(new JLabel("Loan Amount"));    p1.add(txtLoanAmount);    p1.add(new JLabel("Monthly Payment"));    p1.add(txtMonthlyPayment);    p1.add(new JLabel("Total Payment"));    p1.add(txtTotalPayment);

Answer 1

您需要在 中执行此操作。actionPerformed

public void actionPerformed(ActionEvent e )

{

    //get values from the text fields

    double interest = Double.parseDouble(txtAnnualInterestRate.getText());

    int  year =  Integer.parseInt(txtNumberOfYears.getText());

    double loanAmount = Double.parseDouble(txtLoanAmount.getText());

    Loan loan = new Loan(interest, year, loanAmount);//see page 376 for source for loan object

    //display the monthly total payment and monthly payment

    txtMonthlyPayment.setText(String.format("%.2f", loan.getMonthlyPayment()));

    txtMonthlyPayment.setBackground(Color.YELLOW);

    txtTotalPayment.setText(String.format("%.2f", loan.getTotalPayment()));

    txtTotalPayment.setBackground(Color.YELLOW);

}//end action performed

对于您的第二个问题，您可以使用设置字体。例如java.awt.Font

txtMonthlyPayment.setFont(new Font("font name",font_style(int),size(int));