Question

代码应该从文本文件的一行文本中读取并处理它，将其添加到已处理行的数组中，然后返回数组

但是当我尝试返回数组时，我一直收到错误。我假设我在代码正文中做错了什么

static public Media[] importMedia(String fileName){
        try {
        FileReader fileReader = new FileReader(fileName);
        BufferedReader br = new BufferedReader(fileReader);
        System.out.println("Reading metadata file: "+fileName);

        int len=new Integer(br.readLine()); //read number of entries in file

        //read line in text file
        //process line using createMedia
        //add media to array of media objects

        Media media = createMedia(br.readLine());
        Media[] newMedia = new Media[len];

        for(int i = 0;i<=len;i++){
            newMedia[i] = media;
        }
        //return newMedia
        br.close();
    } catch (IOException e){
        System.out.println("IO error reading "+fileName);

    }
    return newMedia;
}

Answer 1

问题在于，您尝试返回的数组位于try-catch块中，并且无法在return关键字外部访问。

尝试此更新：

    var xml = "<?xml version='1.0' encoding='utf-8'?><campaign guid='799223B1-24A7-4F01-8DAE-632E6F68F845'><LeaderBoard><Target Rank='1' TotalScore='138000' FirstName='Shane' LastName='Foster' TargetCompanyName='[Acme]' DisplayName=''>Hello World</Target></LeaderBoard></campaign>",
        xmlDoc = $.parseXML(xml),
        $xml = $(xmlDoc),
        $title = $xml.find("Target");

        alert($title.text());

Answer 2

对我而言，最直接的事情是你的返回变量是在try的主体内声明的。如果在创建变量之前抛出IOException（很可能因为所有IO都在它之上），所以不会返回newMedia。

将newMedia的声明移出try，并在try和catch中初始化它。

static public Media[] importMedia(String fileName){
    Media[] newMedia;
    try {
        FileReader fileReader = new FileReader(fileName);
        BufferedReader br = new BufferedReader(fileReader);
        System.out.println("Reading metadata file: "+fileName);

        int len=new Integer(br.readLine()); //read number of entries in file

        //read line in text file
        //process line using createMedia
        //add media to array of media objects

        Media media = createMedia(br.readLine());
        newMedia = new Media[len];

        for(int i = 0;i<=len;i++){
            newMedia[i] = media;
        }
        //return newMedia
        br.close();
    } catch (IOException e){
        System.out.println("IO error reading "+fileName);
        newMedia = null;
    }
    return newMedia;
}

无法解决变量eclipse

2 个答案: