我似乎無法使這種繼承起作用

Question

我有一個選項卡式應用程序。 您可以在其中一個標簽中輸入公司名稱，並且公司名稱應更改為您在另一個標簽中鍵入的名稱。 這是兩個類。

在此代碼上，它告訴我更改About.setCompanyName（str）;。 靜態

我看到的錯誤是“無法從About類型靜態引用非靜態方法SetCompanyName（String）”

package CourseProject;

import java.awt.Color;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Insets;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.*;

import javax.swing.*;

public class Options extends JPanel{

    private JLabel changeLabel;
    private JTextField changeName;
    private JButton setName;
    private JButton exitButton;

    public Options(){
        GridBagLayout gridbag = new GridBagLayout();
        GridBagConstraints c = new GridBagConstraints();
        c.fill = GridBagConstraints.NORTH;
        setBackground(Color.WHITE);
        super.setLayout(gridbag);
        c.insets = new Insets(10, 10, 10, 10);

        changeLabel = new JLabel("Change Company Name:");
        changeName = new JTextField("", 10);
        setName = new JButton("Set New Name");
        exitButton = new JButton("Exit");       

        c.gridx = 0;
        c.gridy = 0;
        c.gridwidth = 2;
        add(changeLabel, c);        

        c.gridx = 0;
        c.gridy = 1;    
        add(changeName, c);     

        c.gridx = 0;
        c.gridy = 2;
        c.gridwidth = 1;
        add(setName, c);
        setName.addActionListener(new setNameAction());

        c.gridx = 1;
        c.gridy = 2;    
        add(exitButton, c);
        exitButton.addActionListener(new exitApp());
        exitButton.setSize(40,40);      
    }
    class setNameAction implements ActionListener
    {
        public void actionPerformed(ActionEvent e)
        {

            String str;
            str = changeName.getText();
            About.SetCompanyName(str);
            changeName.setText("");
        }

    }
    class exitApp implements ActionListener
    {
        public void actionPerformed(ActionEvent e)
        {
            System.exit(0);
        }
    }
}

這是“關於”，其中包含我的二傳手。 它要求我將方法和變量設為靜態，但是我知道這將無法工作，因為我想更改它

package CourseProject;

import java.awt.Color;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Insets;

import javax.swing.JLabel;
import javax.swing.JPanel;

public class About extends JPanel{

    private JLabel programInfoLabel;
    private JLabel programInfo;
    private JLabel programmerLabel;
    private JLabel programmer;
    private JLabel companyLabel;
    JLabel company;
    public String companyName = "enter a company name in options";

    public About() {        

        GridBagLayout gridbag = new GridBagLayout();
        GridBagConstraints c = new GridBagConstraints();
        c.fill = GridBagConstraints.NORTH;
        setBackground(Color.WHITE);
        super.setLayout(gridbag);
        c.insets = new Insets(10, 10, 10, 10);

        programInfoLabel = new JLabel("Program Information:");
        programInfo = new JLabel("This is the CIS355A course project application");
        programmerLabel = new JLabel("Programmer:");
        programmer = new JLabel("Kevin Rankin");
        companyLabel = new JLabel("Company Name:");
        company = new JLabel(companyName);

        c.gridx = 0;
        c.gridy = 0;    
        add(programInfoLabel, c);

        c.gridx = 1;
        c.gridy = 0;    
        add(programInfo, c);

        c.gridx = 0;
        c.gridy = 1;
        add(programmerLabel, c);

        c.gridx = 1;
        c.gridy = 1;
        add(programmer, c);

        c.gridx = 0;
        c.gridy = 2;
        add(companyLabel, c);

        c.gridx = 1;
        c.gridy = 2;
        add(company, c);
    }
    public void SetCompanyName(String str){
        company.setText(str);
    }   
}

Answer 1

在這條線上

About.SetCompanyName(str);

您正在靜態調用SetCompanyName（通過使用類名“ About”）。 您應該使方法靜態（與“ final”不同；您似乎對此感到困惑），或者首先創建About類的實例，如下所示：

About myAboutObject = new About();
myAboutObject.SetCompanyName(str);