文件在Java中被读取为空文件

Question

我有以下代码要读取带有一堆键/值对的文件，我知道该键存在并且不为空。但是，当我运行它时，我看到我的“行为空” printf。有指针吗？我是一名菜鸟Java程序员。

    String oldContent = "";
    File fileToBeModified = new File("/some_path/gradle.properties");
    try (BufferedReader reader = new BufferedReader(new FileReader(fileToBeModified))) {
        //Reading all the lines of input text file into oldContent
        String line = reader.readLine();
        if (line == null) {
            System.out.println("line is null");
        }
        while (line != null) {
            if (line.contains("version=")) {
                oldVersion = line;
            }
            oldContent = oldContent + line + System.lineSeparator();
            line = reader.readLine();
        }

        if (oldContent.isEmpty()) {
            System.out.println("file is empty");
        }
    }
    catch(...) {
        ...
    }

该文件具有（这是gradle.properties文本文件），并且具有0644个权限。

group=com.mycompany.mygroup
s3_bucket=war-uploads/maven/repository

#DO NOT REMOVE: Random number(256161) to force rebase from master if necessary.
version=1.0.0

Answer 1

此代码有效：

   String oldContent = "";
    String fileToBeModified = "c://temp//gradle.properties";
    try (BufferedReader reader = new BufferedReader(new FileReader(fileToBeModified))) {
        //Reading all the lines of input text file into oldContent
        String line = reader.readLine();
        if (line == null) {
            System.out.println("line is null");
        }
        while (line != null) {
            if (line.contains("version=")) {
                String oldVersion = line;
            }
            oldContent = oldContent + line + System.lineSeparator();
            line = reader.readLine();
        }

        if (oldContent.isEmpty()) {
            System.out.println("file is empty");
        }
    }
    catch(Exception e) {
        e.printStackTrace();
    }