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标题:
求解
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作者:
CHJ
时间:
2013-9-29 22:10
标题:
求解
本帖最后由 CHJ 于 2013-9-29 22:24 编辑
import java.io.*;
class CopyTestByBuf
{
public static void main(String[] args)
{
BufferedReader bufr = null;
BufferedWriter bufw = null;
try
{
new BufferedReader(new FileReader("CopyTest.java"));
new BufferedWriter(new FileWriter("CopyTest_1.txt"));
String s = null;
while ((s=bufr.readLine())!=null)
{
bufw.write(s);
bufw.newLine();
bufw.flush();
}
}
catch (IOException e)
{
throw new RuntimeException("读写失败!");
}
finally
{
try
{
if (bufr!=null)
{
bufr.close();
}
}
catch (IOException e)
{
throw new RuntimeException("读失败!");
}
try
{
if (bufw!=null)
{
bufw.close();
}
}
catch (IOException e)
{
throw new RuntimeException("写失败!");
}
}
}
}
复制代码
编译通过了,运行就出现这个异常Exception in thread "main" java.lang.NullPointerException
at CopyTestByBuf.main(CopyTestByBuf.java:15)
作者:
雪人
时间:
2013-9-29 22:14
new BufferedReader(new FileReader("CopyTest.java"));
new BufferedWriter(new FileWriter("CopyTest_1.txt"));
这么是不对的...
bufr = new BufferedReader(new FileReader("CopyTest.java"));
bufw = new BufferedWriter(new FileWriter("CopyTest_1.txt"));
你得给它们赋值啊...先声明再赋值...你这相当于只是声明了...
作者:
xscn
时间:
2013-9-29 22:30
NullPointerException异常
只创建引用指向空,未赋值
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