TextField的getText（）方法不起作用 [英] getText() method of TextField not working

问题描述

if-else in actionPerformed（）根本不起作用。有人请任何帮助我。谢谢

If-else in actionPerformed() is not working at all. Someone please any help me. Thank you

import java.awt.*;
import java.awt.event.*;
import java.io.*;

public class MyFileDialog implements ActionListener
{
    FileDialog fd;
    Button btn;
    TextArea txtAr;
    TextField txtPath;
    GridBagLayout gblo;
    GridBagConstraints gbc;
    Frame frm;
    Label lbl1;
    
    MyFileDialog()
    {
        frm=new Frame("File Dialog");
        frm.setVisible(true);
        frm.setSize(700, 700);
        frm.setLocation(250,250);
        gblo=new GridBagLayout();
        gbc=new GridBagConstraints();
        
        frm.setLayout(gblo);
        
        gbc.fill=GridBagConstraints.BOTH;
        gbc.anchor=GridBagConstraints.CENTER;
        
        //gbc.weightx=0.0;
        gbc.insets.left=0;
        gbc.insets.right=0;
       //frm.add(lbl1=new Label("Enter file name: ",Label.LEFT));       
        //gblo.setConstraints(lbl1, gbc);
        
        gbc.insets.left=2;
        gbc.insets.bottom=5;
        frm.add(txtPath=new TextField(30));
        gblo.setConstraints(txtPath, gbc);
        
        gbc.insets.left=5;
        gbc.insets.top=5;
        gbc.gridwidth=GridBagConstraints.REMAINDER;
        frm.add(btn=new Button("  Load  "));
        btn.setSize(20,10);
        gblo.setConstraints(btn, gbc);
        btn.addActionListener(this);
        
        gbc.insets.left=1;
        gbc.gridwidth=2;
        frm.add(txtAr=new TextArea("",20,70,TextArea.SCROLLBARS_BOTH));
        
        
        frm.addWindowListener(new WindowAdapter()
                                                   {@Override
                                                   public void windowClosing(WindowEvent we)
                                                   {
                                                        frm.setVisible(false);
                                                        System.exit(0);
                                                   }});
    }

    @Override
    public void actionPerformed(ActionEvent e)
    {   
        String dir="";
        if(txtPath.getText()==""||txtPath.getText()==null)
        {
            
            fd=new FileDialog(frm,"Load your file",FileDialog.LOAD);
            fd.setVisible(true);

            dir=fd.getDirectory()+fd.getFile();
            txtPath.setText(dir);
            
        }
        else
            dir=txtPath.getText();
        
        loadFile(dir);
    }
    
    public void loadFile(String path)
    {
        try
        {
            FileInputStream fis=new FileInputStream(path);
            int space=fis.available();
            byte []buffer=new byte[space];
            
            fis.read(buffer);
                       
            String fileContent=new String(buffer);
            txtAr.setText(fileContent);            
        }
        catch(IOException e)
        {
            txtAr.setText("File cannot be loaded");    
        }       
    }
    
    public static void main(String args[])
    {
           new MyFileDialog();
    }
}

推荐答案

你好，



尝试更改if条件，如下所示。

Hello,

Try changing your if condition as shown below.

if (txtPath.getText() != null && txtPath.getText().trim().length > 0)
    dir=txtPath.getText();
else {
    fd = new FileDialog(frm, "Load your file", FileDialog.LOAD);
    fd.setVisible(true);

    dir=fd.getDirectory() + fd.getFile();
    txtPath.setText(dir);
}

您还可以使用 StringUtils.isEmpty 或 StringUtils.IsBlank 来自 commons lang library 一个用于执行字符串相关操作的null安全助手类。



问候，

You can also use StringUtils.isEmpty or StringUtils.IsBlank from commons lang library a null safe helper class for performing string related operations.

Regards,

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