报cannot resolve symbol怎么处理

[cqin]

IOTest.java:19: cannot resolve symbol
symbol : variable in
location: class IOTest
myline = in.readLine();
^
IOTest.java:23: cannot resolve symbol
symbol : variable in
location: class IOTest
myline = in.readLine();
^
2 errors


代码如下：
import java.io.*;
public class IOTest
{

public static void main(String args[]) // thrown FileNotFoundException
{
String myline;
try
{
BufferedReader in = new BufferedReader(new FileReader("Hello.java"));
}
catch(FileNotFoundException e)
{
System.out.println("Got one file exception");
e.printStackTrace();
}
try
{
myline = in.readLine();
while (myline != null)
{
System.out.println(myline);
myline = in.readLine();
}
}
catch (IOException e2)
{
System.out.println("Got one readline Exception");
e2.printStackTrace();
}
}
}

[ppxstar]

try
{
BufferedReader in = new BufferedReader(new FileReader("Hello.java"));
}

这一句，让你的变量in成了局部变量，使用范围只能在try{}里面
你应当这样写。
BufferedReader in;
try
{
in = new BufferedReader(new FileReader("Hello.java"));
}

[weimenren]

import java.io.*;
public class IOTest
{

public static void main(String args[]) // thrown FileNotFoundException
{
String myline;

try
{
BufferedReader in = new BufferedReader(new FileReader("Hello.java"));
myline = in.readLine();
while (myline != null)
{
System.out.println(myline);
myline = in.readLine();
}
}
catch(FileNotFoundException e)
{
System.out.println("Got one file exception");
e.printStackTrace();
}
catch (IOException e2)
{
System.out.println("Got one readline Exception");
e2.printStackTrace();
}
}
}


以上是改好的程序，cannot resolve symbol 的意思一般是变量没有定义，或者方法没有定义的意思，你原先的程序in在try{}中定义的，那么它的作用域就在{}中，外，假如你在try{}外定义的话，第二个myline = in.readLine();会怀疑你没有初始化in，而要求你初始化，所以最好把这些语句放在一起，当然可以分别捕获异常