java Applet中线程“AWT-EventQueue-1”中的异常java.lang.NullPointerException(Exception in thread “AWT-EventQueue-1” java.lang.NullPointerException in java Applet)
我在java中创建一个程序，它从applet读取文本文件，并将颜色放在由文件定义的applet窗口像素中。 问题是当我运行这个程序时，Exception发生了，我已经完成了我所知道的所有事情来解决它但没有成功。
我的applet代码是
GUIIO.java
import java.applet.Applet; import java.awt.Color; import java.awt.Graphics; import java.awt.Point; import java.io.BufferedReader; import java.io.FileInputStream; import java.io.IOException; import java.io.InputStream; import java.io.InputStreamReader; public class GUIIO extends Applet { Color color = new Color(2); InputStream inputStream; BufferedReader bufferedReader; @Override public void init() { try { inputStream = new FileInputStream("Sample In.txt"); } catch (Exception e) { e.printStackTrace(); } } @Override public void paint(Graphics g) { Point point = new Point(); try { bufferedReader = new BufferedReader(new InputStreamReader(inputStream)); point = this.getImageResolution(bufferedReader); char c, ch[] = {'a', 'b', 'c', 'd', 'e', 'f' }; int i = 0, x = 0, y = 0; putPixel(1, 100, String.valueOf(ch), g); while((c = (char)bufferedReader.read()) != 'z') { if(c == 'y') { y++; x = 0; } else if(i < 6) { ch[i] = c; i++; } if (i == 6) { putPixel(x, y, String.valueOf(ch), g); x++; i = 0; ch[i] = c; } } } catch (IOException e) { e.printStackTrace(); } g.drawString(point.x+" "+point.y, 30, 10); repaint(); } private Point getImageResolution(BufferedReader bufferedReader) throws IOException { boolean xFlag = false; StringBuilder x = new StringBuilder(), y = new StringBuilder(); String check = null; char chars[] = bufferedReader.readLine().toCharArray(); for(int i=0;i<chars.length;i++) { check = String.valueOf(chars[i]); if(check.equals("x")) xFlag = true; else if(xFlag == true) y.append(check); else x.append(check); } Point point = new Point(); point.x = Integer.parseInt(x.toString()); point.y = Integer.parseInt(y.toString()); return point; } private void putPixel(int x, int y, String color, Graphics g) { g.setColor(Color.decode("0x"+color)); g.drawLine(x, y, x, y); } }输入文本文件。
样本In.txt
8x8 000000ff000000ff000000ff000000ff000000ff000000ffy000000ff000000ff000000ff000000ff000000ff000000ffy000000ff000000ff000000ff000000ff000000ff000000ffy000000ff000000ff000000ff000000ff000000ff000000ffy000000ff000000ff000000ff000000ff000000ff000000ffy000000ff000000ff000000ff000000ff000000ff000000ffy000000ff000000ff000000ff000000ff000000ff000000ffy000000ff000000ff000000ff000000ff000000ff000000ffyz我在eclipse中遇到的异常或错误
Exception in thread "AWT-EventQueue-1" java.lang.NullPointerException at GUIIO.getImageResolution(GUIIO.java:61) at GUIIO.paint(GUIIO.java:30) at sun.awt.RepaintArea.paintComponent(Unknown Source) at sun.awt.RepaintArea.paint(Unknown Source) at sun.awt.windows.WComponentPeer.handleEvent(Unknown Source) at java.awt.Component.dispatchEventImpl(Unknown Source) at java.awt.Container.dispatchEventImpl(Unknown Source) at java.awt.Component.dispatchEvent(Unknown Source) at java.awt.EventQueue.dispatchEventImpl(Unknown Source) at java.awt.EventQueue.access$400(Unknown Source) at java.awt.EventQueue$3.run(Unknown Source) at java.awt.EventQueue$3.run(Unknown Source) at java.security.AccessController.doPrivileged(Native Method) at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source) at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source) at java.awt.EventQueue$4.run(Unknown Source) at java.awt.EventQueue$4.run(Unknown Source) at java.security.AccessController.doPrivileged(Native Method) at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source) at java.awt.EventQueue.dispatchEvent(Unknown Source) at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source) at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source) at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source) at java.awt.EventDispatchThread.pumpEvents(Unknown Source) at java.awt.EventDispatchThread.pumpEvents(Unknown Source) at java.awt.EventDispatchThread.run(Unknown Source)更新：我已经在cmd中尝试了这个代码它运行得很完美但是当我调整窗口大小时我会给出同样的错误。
请帮忙。
I am creating a program in java which reads a text file from applet and puts colors in applet window pixels defined by file. The problem is that when i run this program the Exception occurs and i have done everything i know to resolve it but didn't succeed.
My applet code is
GUIIO.java
import java.applet.Applet; import java.awt.Color; import java.awt.Graphics; import java.awt.Point; import java.io.BufferedReader; import java.io.FileInputStream; import java.io.IOException; import java.io.InputStream; import java.io.InputStreamReader; public class GUIIO extends Applet { Color color = new Color(2); InputStream inputStream; BufferedReader bufferedReader; @Override public void init() { try { inputStream = new FileInputStream("Sample In.txt"); } catch (Exception e) { e.printStackTrace(); } } @Override public void paint(Graphics g) { Point point = new Point(); try { bufferedReader = new BufferedReader(new InputStreamReader(inputStream)); point = this.getImageResolution(bufferedReader); char c, ch[] = {'a', 'b', 'c', 'd', 'e', 'f' }; int i = 0, x = 0, y = 0; putPixel(1, 100, String.valueOf(ch), g); while((c = (char)bufferedReader.read()) != 'z') { if(c == 'y') { y++; x = 0; } else if(i < 6) { ch[i] = c; i++; } if (i == 6) { putPixel(x, y, String.valueOf(ch), g); x++; i = 0; ch[i] = c; } } } catch (IOException e) { e.printStackTrace(); } g.drawString(point.x+" "+point.y, 30, 10); repaint(); } private Point getImageResolution(BufferedReader bufferedReader) throws IOException { boolean xFlag = false; StringBuilder x = new StringBuilder(), y = new StringBuilder(); String check = null; char chars[] = bufferedReader.readLine().toCharArray(); for(int i=0;i<chars.length;i++) { check = String.valueOf(chars[i]); if(check.equals("x")) xFlag = true; else if(xFlag == true) y.append(check); else x.append(check); } Point point = new Point(); point.x = Integer.parseInt(x.toString()); point.y = Integer.parseInt(y.toString()); return point; } private void putPixel(int x, int y, String color, Graphics g) { g.setColor(Color.decode("0x"+color)); g.drawLine(x, y, x, y); } }The input text file.
Sample In.txt
8x8 000000ff000000ff000000ff000000ff000000ff000000ffy000000ff000000ff000000ff000000ff000000ff000000ffy000000ff000000ff000000ff000000ff000000ff000000ffy000000ff000000ff000000ff000000ff000000ff000000ffy000000ff000000ff000000ff000000ff000000ff000000ffy000000ff000000ff000000ff000000ff000000ff000000ffy000000ff000000ff000000ff000000ff000000ff000000ffy000000ff000000ff000000ff000000ff000000ff000000ffyzThe exception or error i have got in eclipse
Exception in thread "AWT-EventQueue-1" java.lang.NullPointerException at GUIIO.getImageResolution(GUIIO.java:61) at GUIIO.paint(GUIIO.java:30) at sun.awt.RepaintArea.paintComponent(Unknown Source) at sun.awt.RepaintArea.paint(Unknown Source) at sun.awt.windows.WComponentPeer.handleEvent(Unknown Source) at java.awt.Component.dispatchEventImpl(Unknown Source) at java.awt.Container.dispatchEventImpl(Unknown Source) at java.awt.Component.dispatchEvent(Unknown Source) at java.awt.EventQueue.dispatchEventImpl(Unknown Source) at java.awt.EventQueue.access$400(Unknown Source) at java.awt.EventQueue$3.run(Unknown Source) at java.awt.EventQueue$3.run(Unknown Source) at java.security.AccessController.doPrivileged(Native Method) at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source) at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source) at java.awt.EventQueue$4.run(Unknown Source) at java.awt.EventQueue$4.run(Unknown Source) at java.security.AccessController.doPrivileged(Native Method) at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source) at java.awt.EventQueue.dispatchEvent(Unknown Source) at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source) at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source) at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source) at java.awt.EventDispatchThread.pumpEvents(Unknown Source) at java.awt.EventDispatchThread.pumpEvents(Unknown Source) at java.awt.EventDispatchThread.run(Unknown Source)Update: I have tried this code in cmd it runs perfectly but when i resized the window i gives same error.
Please help.
最满意答案
您的代码中存在多个问题。 首先，您无法读取和读取bufferedReader，因为在某些时候它将为空，并且您不会检查从bufferedReader读取的行是否为空。
还有另一个问题，有时你的颜色字符串是?????? 。
为什么每次重新绘制apllet时都会读取文件？ 您可以在init（）方法中读取一次文件，就是这样！
There are muliple issues in your Code. First you can't read and read and read from your bufferedReader because at sometime it will be empty and you don't check if the line that you read from the bufferedReader is null.
There is also another problem, sometimes your color String is ?????? .
Why do you read the file every time the apllet is repainted? You could read the file once in your init() methode and that's it!
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