尝试读取多行 cmd 输入

Question

I'm trying to write a method that:

• Prints out a message (Something like: "Paste your input: ")
• Waits that the user presses enter.
• Reads all the lines, that got pasted and adds them up in one String.

(An empty line can be used to determine the end of the input.)

The first syso does the printing part and also the first line gets read correctly, but then it never exits the while loop. Why? There has to be an end?

public static String readInput(String msg) {
    System.out.print(msg);
    String res = "";
    try (BufferedReader buffer = new BufferedReader(new InputStreamReader(System.in))) {
        String line;
        while ((line = buffer.readLine()) != null && !line.isBlank())
            res += "\n" + line;
    } catch (IOException e) {
        e.printStackTrace();
    }
    return res;
}

Ive already seen the following sites, but they all didn't help:

• How to read input with multiple lines in Java
• https://www.techiedelight.com/read-multi-line-input-console-java/
• Make the console wait for a user input to close

Edit:

The same bug applies for:

public static String readInput(String msg) {
        System.out.print(msg);
        String res = "";
        try (BufferedReader buffer = new BufferedReader(new InputStreamReader(System.in))) {
            res = buffer.lines().reduce("", (r, l) -> r + "\n" + l);
            System.out.println(res);
        } catch (IOException e) {
            e.printStackTrace();
        }
        return res;
    }

Edit 2: I've tried this code in my actual project and in a new test-project, but with different results. Here is a video of that test.

Answer 1

Why wouldn't use this statement?

 while (!(line = buffer.readLine()).isEmpty())

In this case sending empty line will exit the loop.

Although, if you insert large text with empty lines (for example, the beginning of a new paragraph, or a space between them) will terminate the program.