我一直在尝试创建一个小程序，它只是允许用户选择一个txt文件，然后将文件打印到打印机，
下面是代码：我试图编译它，但我得到了错误main（String args []）已经在类中定义，这个代码在我添加到顶部代码之前工作，允许用户选择一个国际米兰，也将是我想做甚至工作？我想要做的就是在打印机上打印txt文件的内容然后生病了：）
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 main(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;
}
}
下面是重命名的版本，但是我收到一条新的错误消息：找不到符号变量mText
并高亮显示这行代码：
private static final AttributedString mStyledText = new AttributedString(mText);
改进代码：
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;
}
}
答案 0 :(得分：3)
这个错误正是它所说的：你有两个main(String[])方法。每个类中只能有一个具有给定名称和签名的方法。因此，您必须以某种方式修复代码。 （即，为初学者重命名其中一种方法。）
答案 1 :(得分：0)
主要方法是这样开始的：
static public void main(String args[]) {
...
...
}
主要方法是应用程序的入口点。您应该只有一个，以便您的应用程序知道从哪里开始。 您目前拥有这些方法，这就是您的应用程序无法运行的原因。