如何在try/catch块之前初始化InputStream

Question

public static void main(String[] args){

// Get file string until valid input is entered.
System.out.println("Enter file name.\n Enter ';' to exit.");
String fileName = sc.nextLine();
boolean fileLoop = true;
InputStream inFile;

while (fileLoop){
    try{
        inFile = new FileInputStream(fileName);
        fileLoop = false;
    } catch (FileNotFoundException e) {
        System.out.println("That file was not found.\n Please re enter file name.\n Enter ';' to exit.");
        fileName = sc.nextLine();
        if (fileName.equals(";")){
            return;
        }
   } 

}

// ****** This is where the error is. It says inFile may not have been initalized. ***
exampleMethod(inFile);
}

public static void exampleMethod(InputStream inFile){

    // Do stuff with the file.
}

InputStream inFile = new FileInptStream();
// This yeilds an eror because there are no arguments.

InputStream inFile = new InputStream();
// This doesn't work because InputStream is abstract.

如何确保在输入有效输入之前，仍然允许循环，同时初始化此InputStream？

谢谢你

Answer 1

要解决此问题,请更改这一行代码：

InputStream inFile;

对此：

InputStream inFile = null;

您必须这样做的原因是因为Java阻止您使用未初始化的局部变量。使用一个未初始化的变量通常是一个疏忽，因此Java阻止在这种情况下允许使用它。正如@immibis所指出的，这个变量总是会被初始化的，但是编译器不够聪明，无法在这种情况下找到它。