java - 从另一个按钮禁用按钮

Question

我想在单击 btnSearchFile 时禁用按钮 btnCopyFolder

这是我的代码:

 package org.eclipse.wb.swt;

import java.nio.file.Path;

import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.FilenameFilter;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.URI;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.nio.file.StandardCopyOption;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Collection;

import org.eclipse.swt.SWT;
import org.eclipse.swt.events.SelectionAdapter;
import org.eclipse.swt.events.SelectionEvent;
import org.eclipse.swt.widgets.Button;
import org.eclipse.swt.widgets.DateTime;
import org.eclipse.swt.widgets.DirectoryDialog;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.FileDialog;
import org.eclipse.swt.widgets.Label;
import org.eclipse.swt.widgets.Shell;
import org.eclipse.swt.widgets.Text;
import org.eclipse.swt.widgets.ProgressBar;
import org.eclipse.swt.widgets.List;
import org.eclipse.swt.widgets.MessageBox;

public class MainUI {


    private Text txtSource;
    private static Text txtDestination;
    protected Shell shell;
    private static Text text1;
    static DateTime ddFrom;
    static Button btnCopyFolder;
    static String text = "" ;
    static String text2 = "" ;
    /**
     * Open the window.
     */
    public void open() {
        Display display = Display.getDefault();
        createContents();
        shell.open();
        shell.layout();
        while (!shell.isDisposed()) {
            if (!display.readAndDispatch()) {
                display.sleep();
            }
        }
    }
    /**
     * Create contents of the window.
     */
    protected void createContents() {
        shell = new Shell();
        shell.setSize(450, 400);
        shell.setText("Connection Manager");

        final DateTime ddFrom = new DateTime (shell, SWT.DROP_DOWN | SWT.BORDER);
        final DateTime ddTo = new DateTime (shell, SWT.DROP_DOWN | SWT.BORDER);
        text = String.format("%02d/%02d/%04d",ddFrom.getDay(),ddFrom.getMonth() + 1,ddFrom.getYear());
        text2 = String.format("%04d%02d%02d",ddTo.getYear(), ddTo.getMonth() + 1, ddTo.getDay());
        //      final DateTime time = new DateTime (shell,SWT.TIME | SWT.SHORT);

        Label lblNewLabel = new Label(shell, SWT.NONE);
        lblNewLabel.setFont(SWTResourceManager.getFont("Segoe UI", 12, SWT.NORMAL));
        lblNewLabel.setBounds(10, 0, 107, 25);
        lblNewLabel.setText("Source File ");

        Button btnSearchFile = new Button(shell, SWT.NONE);
        btnSearchFile.setBounds(103, 30, 107, 25);
        btnSearchFile.setText("Search File");
        btnSearchFile.addSelectionListener(new SelectionAdapter() {
            public void widgetSelected(SelectionEvent e) {
                FileDialog fd = new FileDialog(shell, SWT.MULTI);
                String firstFile = fd.open();
                btnCopyFolder.setVisible(false);
                if (firstFile != null) {
                    String[] selectedFiles = fd.getFileNames();
                    File file = new File(firstFile);
                    for (int ii = 0; ii < selectedFiles.length; ii++ )
                    {
                        if (file.isFile())
                        {
                            displayFiles(new String[] { file.toString()});
                        }
                        else
                            displayFiles(file.list());
                    }
                }

            }
    });

        txtSource = new Text(shell, SWT.BORDER | SWT.MULTI | SWT.V_SCROLL );
        txtSource.setBounds(10, 61, 414, 34);

        Label lblNewLabel_1 = new Label(shell, SWT.NONE);
        lblNewLabel_1.setFont(SWTResourceManager.getFont("Segoe UI", 11, SWT.NORMAL));
        lblNewLabel_1.setBounds(10, 96, 107, 18);
        lblNewLabel_1.setText("Destination File");

        final Button btnSearchDirectory = new Button(shell, SWT.NONE);
        btnSearchDirectory.setText("Search Directory");
        btnSearchDirectory.setBounds(216, 31, 107, 25);
        btnSearchDirectory.addSelectionListener(new SelectionAdapter() {
            public void widgetSelected(SelectionEvent e) {
                DirectoryDialog dlg = new DirectoryDialog(shell);
                dlg.setFilterPath(txtSource.getText());
                dlg.setMessage("Select a source file to transfer");
                String dir = dlg.open();
                if (dir != null) {
                    txtSource.setText(dir);
                }
            }
        });

        Button btnSearchDestination = new Button(shell, SWT.NONE);
        btnSearchDestination.setBounds(10, 120, 75, 25);
        btnSearchDestination.setText("Search");
        btnSearchDestination.addSelectionListener(new SelectionAdapter() {
            public void widgetSelected(SelectionEvent e) {
                DirectoryDialog dialog = new DirectoryDialog(shell, SWT.SAVE);
                dialog.setFilterPath(txtDestination.getText());
                String dir = dialog.open();
                if(dir != null){
                    txtDestination.setText(dir);
                }
            }
        });

        txtDestination = new Text(shell, SWT.BORDER);
        txtDestination.setBounds(10, 151, 414, 25);
        txtDestination.setText("");

        Label lblNewLabel_2 = new Label(shell, SWT.NONE);
        lblNewLabel_2.setBounds(10, 182, 81, 15);
        lblNewLabel_2.setText("Date Range:");

        Button btnCopyFile = new Button(shell, SWT.NONE);
        btnCopyFile.setBounds(86, 253, 75, 25);
        btnCopyFile.setText("Copy File");

        btnCopyFile.addSelectionListener(new SelectionAdapter() {
            public void widgetSelected(SelectionEvent e) {
                File srcFolder = new File(txtSource.getText());
                File destFolder = new File(txtDestination.getText());

                if(!srcFolder.exists()){
                    MessageBox msgBox = new MessageBox(shell, SWT.ICON_INFORMATION | SWT.OK);
                    msgBox.setText("Information");
                    msgBox.setMessage("Directory does not exist.");
                    msgBox.open();
                    txtSource.setText("");
                    txtDestination.setText("");

                }else{

                    if(txtDestination.getText().isEmpty())
                    {
                        MessageBox msgBox = new MessageBox(shell, SWT.ICON_WARNING | SWT.OK);
                        msgBox.setText("Warning");
                        msgBox.setMessage("Invalid Path..");
                        msgBox.open();
                        txtSource.setText("");
                        txtDestination.setText("");
                    }
                    else
                    {
                        try {
                            copyFolder1(srcFolder,destFolder);
                        } catch (IOException e1) {
                            // TODO Auto-generated catch block
                            e1.printStackTrace();
                        }
                        text1.append("Finished Copying.....\n");
                        MessageBox msgBox = new MessageBox(shell, SWT.ICON_INFORMATION | SWT.OK);
                        msgBox.setText("Information");
                        msgBox.setMessage("Done Copying...");
                        msgBox.open();
                    }
                    text1.append("");
                }
            }
        });
        Button btnCancel = new Button(shell, SWT.NONE);
        btnCancel.addSelectionListener(new SelectionAdapter() {
            @Override
            public void widgetSelected(SelectionEvent arg0)
            {
                text = String.format("%02d/%02d/%04d",ddFrom.getDay(),ddFrom.getMonth() + 1,ddFrom.getYear());
                text2 = String.format("%04d%02d%02d",ddTo.getYear(), ddTo.getMonth() + 1, ddTo.getDay());
                String txt = ("Date Range is: " + " From "+ text + " : " + " To " + text2 + "\n");
                text1.append(txt);
                txtSource.setText("");
                txtDestination.setText("");

            }
        });
        btnCancel.setBounds(167, 253, 75, 25);
        btnCancel.setText("Cancel");

        Label label = new Label(shell, SWT.SEPARATOR | SWT.HORIZONTAL);
        label.setBounds(0, 288, 434, 13);

        Label lblFrom = new Label(shell, SWT.NONE);
        lblFrom.setBounds(50, 203, 55, 15);
        lblFrom.setText("From");

        //DateTime ddFrom = new DateTime(shell, SWT.DROP_DOWN);
        ddFrom.setBounds(50, 224, 119, 23);

        Label label_1 = new Label(shell, SWT.NONE);
        label_1.setFont(SWTResourceManager.getFont("Segoe UI", 13, SWT.NORMAL));
        label_1.setBounds(199, 222, 22, 25);
        label_1.setText(":");

        //DateTime ddTo = new DateTime(shell, SWT.NONE);
        ddTo.setBounds(233, 224, 119, 23);

        Label lblTo = new Label(shell, SWT.NONE);
        lblTo.setText("To");
        lblTo.setBounds(233, 203, 55, 15);

        text1 = new Text(shell, SWT.BORDER | SWT.READ_ONLY | SWT.H_SCROLL | SWT.V_SCROLL | SWT.MULTI);
        text1.setText("Progress\n");
        text1.setEnabled(true);
        text1.setBounds(0, 302, 434, 59);

        Button btnCopyFolder = new Button(shell, SWT.NONE);
        btnCopyFolder.addSelectionListener(new SelectionAdapter() {
            @Override
            public void widgetSelected(SelectionEvent arg0) {
                File srcFolder = new File(txtSource.getText());
                File destFolder = new File(txtDestination.getText());
                if(!srcFolder.exists()){
                    MessageBox msgBox = new MessageBox(shell, SWT.ICON_INFORMATION | SWT.OK);
                    msgBox.setText("Information");
                    msgBox.setMessage("Directory does not exist.");
                    msgBox.open();
                    txtSource.setText("");
                    txtDestination.setText("");
                }else{
                    if(txtDestination.getText().isEmpty())
                    {
                        MessageBox msgBox = new MessageBox(shell, SWT.ICON_WARNING | SWT.OK);
                        msgBox.setText("WARNING");
                        msgBox.setMessage("Invalid Path...");
                        msgBox.open();
                        txtSource.setText("");
                        txtDestination.setText("");
                    }
                    else
                    {
                        try {
                            copyFolder(srcFolder,destFolder);
                        } catch (IOException e1) {
                            // TODO Auto-generated catch block
                            e1.printStackTrace();
                        }
                        text1.append("Finished Copying.....\n");
                        MessageBox msgBox = new MessageBox(shell, SWT.ICON_INFORMATION | SWT.OK);
                        msgBox.setText("Information");
                        msgBox.setMessage("Done Copying...");
                        msgBox.open();
                    }
                }
            }
        });
        btnCopyFolder.setText("Copy Folder");
        btnCopyFolder.setBounds(248, 253, 75, 25);
}
public void displayFiles(String[] files) {
    for (int i = 0; files != null && i < files.length; i++) {
        txtSource.setText(files[i]);
        txtSource.setEditable(true);
    }
}

public static void copyFolder(File src, File dest)
        throws IOException{
    if(src.isDirectory()){
        if (!dest.exists())
        {
            dest.mkdir();
            text1.append("Directory created : " + dest + "\n");
        }
        final String files[] = src.list();
        for (String file : files)
        {
            File srcFile = new File(src, file);
            File destFile = new File(dest, file);

            //Recursive function call
            copyFolder(srcFile, destFile);
        }
    }
    else{
        text1.append("");
        Files.copy(src.toPath(), dest.toPath(), StandardCopyOption.REPLACE_EXISTING);
        text1.append(text + " Copying " + src.getAbsolutePath() + "\n");
//
    }
}
public static void copyFolder1(File src, File dest)
        throws IOException{
    //      String fileName = new SimpleDateFormat("yyyyMMddHHmm'.txt'").format(new DateTime(ddFrom, 0));
    if(src.isDirectory()){
        if (!dest.exists())
        {
            dest.mkdir();
            text1.append("Directory created : " + dest + "\n");
        }
        String files[] = src.list();
        for (String file : files)
        {
            File srcFile = new File(src, file);
            File destFile = new File(dest, file);

            //Recursive function call
            copyFolder1(srcFile, destFile);
        }
    }
    else{
        if(dest.isDirectory())
        {
            copyFile(src, new File (dest, src.getName()));
            text1.append(text + " Copying " + src.getAbsolutePath() + "\n");
        }
        else
        {
            copyFile(src, dest);
        }
        //          }
    }
}
public static void copyFile(File src, File dest) throws IOException
{
    InputStream oInStream = new FileInputStream(src);
    OutputStream oOutStream = new FileOutputStream(dest);

    // Transfer bytes from in to out
    byte[] oBytes = new byte[1024];
    int nLength;
    BufferedInputStream oBuffInputStream = new BufferedInputStream( oInStream );
    while ((nLength = oBuffInputStream.read(oBytes)) > 0)
    {
        oOutStream.write(oBytes, 0, nLength);
    }
    oInStream.close();
    oOutStream.close();
}
/**
 * Launch the application.
 * @param args
 */
public static void main(String[] args) {
    try {
        MainUI window = new MainUI();
        window.open();
    } catch (Exception e) {
        e.printStackTrace();
    }


}


}

这是错误

java.lang.NullPointerException
    at org.eclipse.wb.swt.MainUI$1.widgetSelected(MainUI.java:87)
    at org.eclipse.swt.widgets.TypedListener.handleEvent(Unknown Source)
    at org.eclipse.swt.widgets.EventTable.sendEvent(Unknown Source)
    at org.eclipse.swt.widgets.Widget.sendEvent(Unknown Source)
    at org.eclipse.swt.widgets.Display.runDeferredEvents(Unknown Source)
    at org.eclipse.swt.widgets.Display.readAndDispatch(Unknown Source)
    at org.eclipse.wb.swt.MainUI.open(MainUI.java:56)
    at org.eclipse.wb.swt.MainUI.main(MainUI.java:370)

这是错误所在的行

btnCopyFolder.setVisible(false); //line 100

Answer 1

您正在使用此代码隐藏字段btnCopyFolder

Button btnCopyFolder = new Button(shell, SWT.NONE);

更改为

btnCopyFolder = new Button(shell, SWT.NONE);