java - java中的对象有问题吗？

Question

我正在制作一个根据用户输入是或否使用react的窗口。我在这部分代码中遇到了问题:

public class Mywindow {

public static void main (String [] args){
    windowcontinued object = new windowcontinued();
    object.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); //ISSUE HERE
    object.setSize(700, 1024); //ISSUE HERE
    object.setVisible(true); //ISSUE HERE
                                         }
                }

这些简单的操作应该确保程序在关闭时终止、具有一定的大小并且可见。但由于某种原因，在所有三个操作中我都收到错误消息:

 The method setDefaultCloseOperation(int) is undefined for the type windowcontinued

The method setSize(int, int) is undefined for the type windowcontinued

The method setVisible(boolean) is undefined for the type windowcontinued

尽管如此，所有这些都应该在导入后已经定义。完整代码如下:

主要代码:

package Myguipackage;

import javax.swing.JOptionPane;
import javax.swing.JFrame;
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JLabel;
import javax.swing.JTextField;

public class Mywindow {

public static void main (String [] args){
    windowcontinued object = new windowcontinued();
    object.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
    object.setSize(700, 1024);
    object.setVisible(true);

                                         }
                }

其他类:

package Myguipackage;
import javax.swing.JOptionPane;
import javax.swing.JFrame;
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JLabel;
import javax.swing.JTextField;

public class Windowcontinued{

public JLabel text;
public JTextField textfield;

public windowcontinued(){  //Constructor
/*  super("CHAT");
    setLayout(new FlowLayout());   */   

    text = new JLabel ("Would you like to talk to me?");
        text.add(text);

    textfield = new JTextField ("Yes or no? Erase this and type in your answer!");




                   }






 class hear implements ActionListener{



    public void actionPerformed(ActionEvent event){

        String string = "";

        if(event.getSource()==textfield)
            string = String.format("You typed in %s", event.getActionCommand());

         JOptionPane.showMessageDialog(null, string); //Open a new window that displays String string, which has changed based on which field you hit enter on.




                                                  }



                                         }


                        }

按照 fdsa 的建议使用 extends 关键字后，以下是新代码:

打包 Myguipackage;

import javax.swing.JFrame;
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JLabel;
import javax.swing.JTextField;

public class mywindow extends JFrame{

public static void main (String [] args){
    windowcontinued object = new windowcontinued();
    object.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
    object.setSize(700, 1024);
    object.setVisible(true);
                                         }
                }

尽管 Class windowcontinued 仍然相同。

Answer 1

正如其他发帖者所说，在命名类时请遵循 java 命名约定。它使您的代码更易于遵循。

您似乎对 import 语句的目的感到困惑。导入对象时，只能对该类型的对象使用其方法。如果您希望您的类模仿现有类的功能，则需要扩展原始类，而不仅仅是导入它。