java - 无法让 JTextArea 显示在计算器上

Question

我正在尝试为学校项目制作计算器，但无法显示 JTextArea。我需要一个窗口，以便用户可以看到他们输入计算器的数字和输出。

这是我的代码:

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;
import java.awt.event.ActionListener;

public class Calculator extends JFrame 
{

JButton[] nums = new JButton [10];

JButton num1 = new JButton ("1");
JButton num2 = new JButton ("2");
JButton num3 = new JButton ("3");
JButton num4 = new JButton ("4");
JButton num5 = new JButton ("5");
JButton num6 = new JButton ("6");
JButton num7 = new JButton ("7");
JButton num8 = new JButton ("8");
JButton num9 = new JButton ("9");
JButton num0 = new JButton ("0");
JButton decimal = new JButton (".");
JButton clear = new JButton ("C");
JButton sqrt = new JButton ("\u221A");
JButton mod = new JButton ("%");
JButton dividebyone = new JButton ("1/x");
JButton factorn = new JButton ("!n");

public Calculator ()
{
    JFrame window = new JFrame ("Calculator");
    setSize (260, 325);
    setDefaultCloseOperation (JFrame.EXIT_ON_CLOSE);
    setVisible (true);

    JTextArea screen = new JTextArea (20, 20);
    JScrollPane pls = new JScrollPane (screen);
    screen.setBackground (Color.WHITE);
    screen.setVisible (true);
    getContentPane ().add (pls);

    getContentPane ().add (stylize (num1));
    num1.setBounds (20, 75, 45, 45);
    num1.addActionListener (new ActionListener ()
    {

        public void actionPerformed (ActionEvent e)
        {
            //Execute when button is pressed
            System.out.println ("1");
        }
    }
    );

    getContentPane ().add (stylize (num2));
    num2.setBounds (70, 75, 45, 45);
    num2.addActionListener (new ActionListener ()
    {

        public void actionPerformed (ActionEvent e)
        {
            System.out.println ("2");
        }
    }
    );

    getContentPane ().add (stylize (num3));
    num3.setBounds (120, 75, 45, 45);
    num3.addActionListener (new ActionListener ()
    {

        public void actionPerformed (ActionEvent e)
        {
            System.out.println ("3");
        }
    }
    );

    getContentPane ().add (stylize (num4));
    num4.setBounds (20, 125, 45, 45);
    num4.addActionListener (new ActionListener ()
    {

        public void actionPerformed (ActionEvent e)
        {
            System.out.println ("4");
        }
    }
    );

    getContentPane ().add (stylize (num5));
    num5.setBounds (70, 125, 45, 45);
    num5.addActionListener (new ActionListener ()
    {

        public void actionPerformed (ActionEvent e)
        {
            System.out.println ("5");
        }
    }
    );

    getContentPane ().add (stylize (num6));
    num6.setBounds (120, 125, 45, 45);
    num6.addActionListener (new ActionListener ()
    {

        public void actionPerformed (ActionEvent e)
        {
            System.out.println ("6");
        }
    }
    );

    getContentPane ().add (stylize (num7));
    num7.setBounds (20, 175, 45, 45);
    num7.addActionListener (new ActionListener ()
    {

        public void actionPerformed (ActionEvent e)
        {
            System.out.println ("7");
        }
    }
    );

    getContentPane ().add (stylize (num8));
    num8.setBounds (70, 175, 45, 45);
    num8.addActionListener (new ActionListener ()
    {

        public void actionPerformed (ActionEvent e)
        {
            System.out.println ("8");
        }
    }
    );

    getContentPane ().add (stylize (num9));
    num9.setBounds (120, 175, 45, 45);
    num9.addActionListener (new ActionListener ()
    {

        public void actionPerformed (ActionEvent e)
        {
            System.out.println ("9");
        }
    }
    );

    getContentPane ().add (stylize (num0));
    num0.setBounds (20, 225, 45, 45);
    num0.addActionListener (new ActionListener ()
    {

        public void actionPerformed (ActionEvent e)
        {
            System.out.println ("0");
        }
    }
    );

    getContentPane ().add (stylize (decimal));
    decimal.setBounds (70, 225, 45, 45);
    decimal.addActionListener (new ActionListener ()
    {

        public void actionPerformed (ActionEvent e)
        {
            System.out.println (".");
        }
    }
    );

    getContentPane ().add (stylize (clear));
    clear.setBounds (120, 225, 45, 45);
    clear.addActionListener (new ActionListener ()
    {

        public void actionPerformed (ActionEvent e)
        {
            System.out.println ("c");
        }
    }
    );

    getContentPane ().add (stylize (sqrt));
    sqrt.setBounds (170, 75, 51, 45);
    sqrt.addActionListener (new ActionListener ()
    {

        public void actionPerformed (ActionEvent e)
        {
            System.out.println ("sqrt");
        }
    }
    );

    getContentPane ().add (stylize (mod));
    mod.setBounds (170, 125, 51, 45);
    mod.addActionListener (new ActionListener ()
    {

        public void actionPerformed (ActionEvent e)
        {
            System.out.println ("mod");
        }
    }
    );

    getContentPane ().add (stylize (factorn));
    factorn.setBounds (170, 175, 51, 45);
    factorn.addActionListener (new ActionListener ()
    {

        public void actionPerformed (ActionEvent e)
        {
            System.out.println ("!n");
        }
    }
    );

    getContentPane ().add (stylize (dividebyone));
    dividebyone.setBounds (170, 225, 51, 45);
    dividebyone.addActionListener (new ActionListener ()
    {

        public void actionPerformed (ActionEvent e)
        {
            System.out.println ("1/x");
        }
    }
    );

} //end Calculator


public static JButton stylize (JButton button)
{
    button.setBackground (Color.WHITE);
    return button;
} //end stylize


public static void main (String args[])
{
    new Calculator ();
} //end main
} //end Calculator class

Answer 1

尝试这样做:

Public static void main(String arts[])
{
    Calculator c= new Calculator();
    c.setVisible(true);
}

从构造函数中删除 setVisible(true)。希望这有效。
由于您的框架在添加组件之前是可见的，因此它不会显示您的组件。