java - 代码突出显示为语法错误。为什么？

Question

我是 java 的新手，我正在尝试编写这段代码，但不知何故，它在使用我的变量时将其视为错误。已宣布为ofc。

import java.io.*;

public class FileRead {
     public void readCountries(String file){
         try{
             ObjectInputStream inputStream = new ObjectInputStream(new FileInputStream("countries"));
             Object obj = null;
             while ((obj = inputStream.readObject()) != null) {
                 if (obj instanceof Country) {
                     System.out.println(((Country)obj).toString());
                 }
             }
         } catch (EOFException ex) { //This exception will be caught when EOF is reached
                System.out.println("End of file reached.");
            } catch (ClassNotFoundException ex) {
                ex.printStackTrace();
            } catch (FileNotFoundException ex) {
                ex.printStackTrace();
            } catch (IOException ex) {
                ex.printStackTrace();
            } finally {
                //Close the ObjectInputStream
                try {
                    if (inputStream != null) { //////////ERROR: inputStream cannot be resolved to a variable
                        inputStream.close(); //////////// Same here
                    }
                } catch (IOException ex) {
                    ex.printStackTrace();
                }
            }
        }
}

Answer 1

将您的 inputStream 声明移到 try block 之外。如果您在 try 内部定义，它在 try block 之外是不可见的。

    ObjectInputStream inputStream = null;
    try{
     inputStream = new ObjectInputStream(new  FileInputStream("countries"));
     ........
 }