java - 找不到符号 - 变量 mText

Question

嘿，我一直在编写一些代码，它允许用户选择一个文件，一个txt文件，然后读取文件的内容，然后将内容发送到打印机，本例是hp 8600，但是在编译时我收到错误，找不到符号 - 变量 mText，这是为什么，它应该从上面检索 mText，因为现在应该包含 txt 文件中的所有数据，我做错了什么？

代码:

import java.awt.*;
import java.awt.font.*;
import java.awt.geom.*;
import java.awt.print.*;
import java.text.*;
import java.io.*;
import javax.swing.*;

public class PrintText implements Printable {


    // Below the code will allow the user to select a file and then print out the contents of the file
    public static void main(String[] args) throws IOException {

        //selects the file
        JFileChooser chooser = new JFileChooser();
        chooser.showOpenDialog(null);
        File file = chooser.getSelectedFile();
        String filename = file.getName();
        //System.out.println("You have selected: " + filename);  testing to see if file seleected was right
        String path = file.getAbsolutePath();

        //Reads contents of file into terminal 
        //FileReader fr = new FileReader("filename");
        // FileReader fr = new FileReader("D:/Documents/" + "filename")); 

        FileReader fr = new FileReader(path); 
        BufferedReader br = new BufferedReader(fr); 
        String mText; 
        while((mText = br.readLine()) != null) { 
            //Displays the contents of the file in terminal
            System.out.println(mText); 
        } 
        //fr.close(); 
    } 


        //private static final String mText = 
        //    "This is a test to see if this text will be printed "; //This works perfectly fine

        private static final AttributedString mStyledText = new AttributedString(mText);



    /**
     * Print a single page containing some sample text.
     */
    static public void printer(String args[]) {
        /* Get the representation of the current printer and 
         * the current print job.
         */
        PrinterJob printerJob = PrinterJob.getPrinterJob();
        /* Build a book containing pairs of page painters (Printables)
         * and PageFormats. This example has a single page containing
         * text.
         */
        Book book = new Book();
        book.append(new PrintText(), new PageFormat());
        /* Set the object to be printed (the Book) into the PrinterJob.
         * Doing this before bringing up the print dialog allows the
         * print dialog to correctly display the page range to be printed
         * and to dissallow any print settings not appropriate for the
         * pages to be printed.
         */
        printerJob.setPageable(book);
        /* Show the print dialog to the user. This is an optional step
         * and need not be done if the application wants to perform
         * 'quiet' printing. If the user cancels the print dialog then false
         * is returned. If true is returned we go ahead and print.
         */
        boolean doPrint = printerJob.printDialog();
        if (doPrint) {
            try {
                printerJob.print();
            } catch (PrinterException exception) {
                System.err.println("Printing error: " + exception);
            }
        }
    }

    /**
     * Print a page of text.
     */
    public int print(Graphics g, PageFormat format, int pageIndex) {
        /* We'll assume that Jav2D is available.
         */
        Graphics2D g2d = (Graphics2D) g;
        /* Move the origin from the corner of the Paper to the corner
         * of the imageable area.
         */
        g2d.translate(format.getImageableX(), format.getImageableY());
        /* Set the text color.
         */
        g2d.setPaint(Color.black);
        /* Use a LineBreakMeasurer instance to break our text into
         * lines that fit the imageable area of the page.
         */
        Point2D.Float pen = new Point2D.Float();
        AttributedCharacterIterator charIterator = mStyledText.getIterator();
        LineBreakMeasurer measurer = new LineBreakMeasurer(charIterator, g2d.getFontRenderContext());
        float wrappingWidth = (float) format.getImageableWidth();
        while (measurer.getPosition() < charIterator.getEndIndex()) {
            TextLayout layout = measurer.nextLayout(wrappingWidth);
            pen.y += layout.getAscent();
            float dx = layout.isLeftToRight()? 0 : (wrappingWidth - layout.getAdvance());
            layout.draw(g2d, pen.x + dx, pen.y);
            pen.y += layout.getDescent() + layout.getLeading();
        }
        return Printable.PAGE_EXISTS;
    }
}

Answer 1

目前，mText 仅在 main 方法的范围内定义。如果您希望在 mStyledText 的构造函数中使用它，则需要将 mText 设为 static 类变量:

private static String mText;

拥有非final static类变量被认为是不好的做法，但是为什么不在print中创建AttributedString code> 方法只在需要时使用:

AttributedString mStyledText = new AttributedString(mText);

此外，main 方法中还有很多功能。我会将其移至类实例方法，您可以在其中完全避免使用任何静态变量。