Java:drawImage找不到我的BuffereImage

Question

我已正确设置了BuffereImage，但编译器给我的错误是找不到变量img

代码如下：

URL url = this.getClass().getResource("spooky.gif");
BufferedImage img = ImageIO.read(url);
mt.addImage(img,1);

public void paint(Graphics g)
{
    g.drawImage(img,0,0,300,300,this);
}

这里是Stackoverflow告诉我，我需要添加更多的细节

整个代码如下所示：

import java.util.*;
import java.awt.*;
import java.applet.*;
import java.net.*;
import java.awt.image.BufferedImage;
import javax.imageio.ImageIO;

public class Spooky extends Applet
{
Image scary, trumpet, walking;
URL url = this.getClass().getResource("spooky.gif");
MediaTracker mt;
AudioClip spoopy;
Graphics buffer;
Image offscreen;
Dimension dim;


public void init()
{
    setLayout(null);
    mt = new MediaTracker(this);
    url = getDocumentBase();
    BufferedImage img = ImageIO.read(url);
    scary = getImage(url,"scary.gif");
    trumpet = getImage(url,"trumpet.gif");
    walking = getImage(url,"walking.gif");
    mt.addImage(img,1);
    mt.addImage(scary,1);
    mt.addImage(trumpet,1);
    mt.addImage(walking,1);
    try{
        mt.waitForAll();
    }
    catch(InterruptedException e){}
    spoopy = getAudioClip(getDocumentBase(),"spoopy.wav");
    spoopy.loop();
}

public void paint(Graphics g)
{
    g.drawImage(img,0,0,300,300,this);
}
}

Answer 1

您正在调用其作用域之外的变量。 无法访问该变量，因为在paint函数中使用该变量时，您在init函数中声明并初始化了该变量。 尝试以下方法：

import java.util.*;
import java.awt.*;
import java.applet.*;
import java.net.*;
import java.awt.image.BufferedImage;
import javax.imageio.ImageIO;

public class Spooky extends Applet
{
Image scary, trumpet, walking;
URL url = this.getClass().getResource("spooky.gif");
MediaTracker mt;
AudioClip spoopy;
Graphics buffer;
Image offscreen;
Dimension dim;
BufferedImage img;

public void init()
{
    setLayout(null);
    mt = new MediaTracker(this);
    url = getDocumentBase();
    img = ImageIO.read(url);
    scary = getImage(url,"scary.gif");
    trumpet = getImage(url,"trumpet.gif");
    walking = getImage(url,"walking.gif");
    mt.addImage(img,1);
    mt.addImage(scary,1);
    mt.addImage(trumpet,1);
    mt.addImage(walking,1);
    try{
        mt.waitForAll();
    }
    catch(InterruptedException e){}
    spoopy = getAudioClip(getDocumentBase(),"spoopy.wav");
    spoopy.loop();
}

public void paint(Graphics g)
{
    g.drawImage(img,0,0,300,300,this);
}
}

Answer 2

以下是我的解决方案：

import java.util.*;
import java.awt.*;
import java.applet.*;
import java.net.*;
import java.awt.image.BufferedImage;
import javax.imageio.ImageIO;
import java.io.*;

public class Spooky extends Applet
{
Image scary, trumpet, walking;
MediaTracker mt;
AudioClip spoopy;
Graphics buffer;
Image offscreen;
Dimension dim;

public void init()
{
setLayout(null);
mt = new MediaTracker(this);


mt.addImage(scary,1);
mt.addImage(trumpet,1);
mt.addImage(walking,1);
spoopy = getAudioClip(getDocumentBase(),"spoopy.wav");
spoopy.loop();
}

public void paint(Graphics g)
{
  try
{
    URL url = this.getClass().getResource("spooky.gif");
    BufferedImage img;
    img = ImageIO.read(url);
    mt.addImage(img,1);
    g.drawImage(img,0,0,300,300,this);
}
catch(IOException e)
{
}

}
}