公共字符串 - 无法解析

Question

发生错误

bw.write(dataString);

我该如何解决这个问题？
dataString 无法解析为变量。

public class test {
        public static void main(String[] args){
            ArrayList<String> data = new ArrayList<String>();

            try (BufferedReader br = new BufferedReader(new FileReader("src/test.txt"))) {
            String CurrLine;

            while((CurrLine = br.readLine()) != null) {
                data.add(CurrLine);
            }
            String[] dataArray = new String[data.size()];
            String dataString = Arrays.toString(dataArray);

            String[] client = dataString.split("<::>");
            Integer nameId = Arrays.binarySearch(client, "Test");
            Integer versId = nameId + 1;
            System.out.println(client[nameId] + "\n" + client[versId]);


        } catch(FileNotFoundException ex) {
        System.out.println("FNFE");
        } catch(IOException ex) {
            System.out.println("IOE");
        }
            try{
                File file = new File("src/test.txt");
                if (!file.exists()) {
                file.createNewFile();
                }
                FileWriter fw = new FileWriter(file);
                BufferedWriter bw = new BufferedWriter(fw);
        bw.write(dataString);
                bw.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
    }

Answer 1

在 try and catch 块之外声明dataString... 仅此而已。 ;) 如果你在循环中声明它，或者在这种情况下是你的 try catch 块，它的生命周期仅限于它。

像这样：

String dataString = null;

在 try-catch 块内：

dataString = Arrays.toString(dataArray);

Answer 2

dataString 超出了 try 块的范围。

也许将 dataString 作为实例变量添加到类的顶部。

public class test {
        private String dataString = null;
        public static void main(String[] args){
            ArrayList<String> data = new ArrayList<String>();

            try (BufferedReader br = new BufferedReader(new FileReader("src/test.txt"))) {
            String CurrLine;

            while((CurrLine = br.readLine()) != null) {
                data.add(CurrLine);
            }
            String[] dataArray = new String[data.size()];
            dataString = Arrays.toString(dataArray);
         ...

Answer 3

dataString 变量的范围仅限于第一个 try-catch 块。将其声明更改如下，

public static void main(String[] args){
    ArrayList<String> data = new ArrayList<String>();
    String dataString = null;

    try (BufferedReader br = new BufferedReader(new FileReader("src/test.txt"))) {
        String CurrLine;

        while((CurrLine = br.readLine()) != null) {
            data.add(CurrLine);
        }
        String[] dataArray = new String[data.size()];
        dataString = Arrays.toString(dataArray);

        String[] client = dataString.split("<::>");
        Integer nameId = Arrays.binarySearch(client, "Test");
        Integer versId = nameId + 1;
        System.out.println(client[nameId] + "\n" + client[versId]);


    } catch(FileNotFoundException ex) {
        System.out.println("FNFE");
    } catch(IOException ex) {
        System.out.println("IOE");
    }
    try{
        File file = new File("src/test.txt");
        if (!file.exists()) {
            file.createNewFile();
        }
        FileWriter fw = new FileWriter(file);
        BufferedWriter bw = new BufferedWriter(fw);
        bw.write(dataString);
        bw.close();
    } catch (IOException e) {
        e.printStackTrace();
    }
}