Question

我正在编写实现ActionListener的代码，所以在我的actionPerformed()函数中（实现ActionListener时这是必需的）我在每个if event.getSource()中都使用了JComponent / else子句用于查找触发了哪个JComponents（因为我的代码中有多个if）。但由于某种原因，只有第一个JComponent语句由其public void actionPerformed(ActionEvent event) { if (event.getSource() == newProj || event.getSource() == newFlick) { String nameProj = JOptionPane.showInputDialog("Name of your Flick:"); int option = 0; JFileChooser dirChooser = new JFileChooser(); if (nameProj != null) { dirChooser.setCurrentDirectory(new File("~")); dirChooser.setDialogTitle("Choose Directory"); dirChooser.setFileSelectionMode(JFileChooser.DIRECTORIES_ONLY); dirChooser.setAcceptAllFileFilterUsed(false); option = dirChooser.showOpenDialog(this); } if (option == JFileChooser.APPROVE_OPTION) { File dir = dirChooser.getSelectedFile(); String dirPath = dir.getAbsolutePath(); String newDirPath = dirPath + "\\" + nameProj; new File(newDirPath).mkdir(); File config = null; try { config = new File(newDirPath + "\\.flick.flick"); if (!config.exists()) { config.createNewFile(); } PrintWriter writer = new PrintWriter(config); writer.append("*WARNING - TAMPERING WITH THIS DATA COULD LEAD TO PROBLEMS IN YOUR FLICK.* \n"); writer.append("Project Name: " + nameProj + "\n"); writer.close(); } catch (FileNotFoundException e) { JOptionPane.showMessageDialog(null, "Error: " + e, null, JOptionPane.ERROR_MESSAGE); } catch (UnsupportedEncodingException e) { JOptionPane.showMessageDialog(null, "Error: " + e, null, JOptionPane.ERROR_MESSAGE); } catch (IOException e) { JOptionPane.showMessageDialog(null, "Error: " + e, null, JOptionPane.ERROR_MESSAGE); } dispose(); new Flick(nameProj); } else if (event.getSource() == loadProj || event.getSource() == loadFlick) { JOptionPane.showMessageDialog(null, "Loaded"); option = 0; dirChooser = new JFileChooser(); dirChooser.setCurrentDirectory(new File("~")); dirChooser.setDialogTitle("Load Flick Directory"); dirChooser.setFileSelectionMode(JFileChooser.DIRECTORIES_ONLY); dirChooser.setAcceptAllFileFilterUsed(false); option = dirChooser.showOpenDialog(this); if (option == JFileChooser.APPROVE_OPTION) { File dir = dirChooser.getSelectedFile(); File config = new File(dir + "\\.flick"); if (config.exists()) { dispose(); new Flick(config.getName()); } else { JOptionPane.showMessageDialog(null, "Error: Not A Flick Directory", null, JOptionPane.ERROR_MESSAGE); } } } } } }触发。代码如下。提前感谢您的帮助。

这是我的问题所关注的代码：

package com.shreypandya.flickstudios;

import java.awt.BorderLayout;
import java.awt.Font;
import java.awt.FontFormatException;
import java.awt.Menu;
import java.awt.MenuBar;
import java.awt.MenuItem;
import java.awt.MenuShortcut;
import java.awt.Panel;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.io.UnsupportedEncodingException;

import javax.swing.JButton;
import javax.swing.JDialog;
import javax.swing.JFileChooser;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;

public class Home extends JFrame implements ActionListener {


private static final long serialVersionUID = 1L;

JLabel title = new JLabel("Welcome to FlickStudios!");
MenuBar menuBar = new MenuBar();
Menu file = new Menu("File");
MenuItem newProj = new MenuItem("New Flick");
MenuItem loadProj = new MenuItem("Load Flick");
JButton newFlick = new JButton("New Flick");
JButton loadFlick = new JButton("Load Flick");
Panel panel = new Panel();

public Home() throws FontFormatException, IOException {

    super("FlickStudios");

    InputStream myStream = new BufferedInputStream(new FileInputStream("Resources/OpenSans.ttf"));
    Font ttf = Font.createFont(Font.TRUETYPE_FONT, myStream);
    Font openSans = ttf.deriveFont(Font.PLAIN, 16);

    add(panel);
    panel.setLayout(new BorderLayout());

    panel.add(title, BorderLayout.PAGE_START);
    title.setFont(openSans.deriveFont(Font.PLAIN, 36));

    panel.add(newFlick, BorderLayout.LINE_START);
    newFlick.setFont(openSans);
    newFlick.setFocusPainted(false);
    newFlick.addActionListener(this);

    panel.add(loadFlick, BorderLayout.LINE_END);
    loadFlick.setFont(openSans);
    loadFlick.setFocusPainted(false);
    loadFlick.addActionListener(this);

    setMenuBar(menuBar);
    menuBar.add(file);

    file.add(newProj);
    newProj.addActionListener(this);
    newProj.setShortcut(new MenuShortcut(KeyEvent.VK_N, false));

    file.add(loadProj);
    loadProj.addActionListener(this);
    loadProj.setShortcut(new MenuShortcut(KeyEvent.VK_L, false));

    setExtendedState(JFrame.MAXIMIZED_BOTH);
    setVisible(true);
    setDefaultCloseOperation(JDialog.EXIT_ON_CLOSE);

    }

以下是前一段代码之前的其余代码：

{{1}}

Answer 1

你的牙套不匹配。

此if (event.getSource() == newProj || event.getSource() == newFlick) {直到：

才会结束

                 } else {

                    JOptionPane.showMessageDialog(null, "Error: Not A Flick Directory", null, JOptionPane.ERROR_MESSAGE);
                }

            }

        }

     }//HERE

因此，如果第一个if语句失败，则函数结束，并且永远不会检查其他条件。

Answer 2

第一个if封装了你的整个函数：

public void actionPerformed(ActionEvent event) {    
   if (event.getSource() == newProj || event.getSource() == newFlick) {    
      if (nameProj != null) {
      }    
      if (option == JFileChooser.APPROVE_OPTION) {            
      } else if (event.getSource() == loadProj || event.getSource() == loadFlick) {    
         if (option == JFileChooser.APPROVE_OPTION) {        
            if (config.exists()) {        
            } else {    
            }    
         }    
      }    
   }
}

我不认为这是你想要的，并且肯定会解释为什么当第一个if评估为false时没有到达内部块。

If / Else Statement - Clause Not Executing Java

2 个答案: