在Java（Android）中使用扫描仪有什么意义

Question

Let me explain in detail, I kept googling about scanners and I can't fully understand what are scanners exactly. I read many articles but all of them say

The java.util.Scanner class is a simple text scanner which can parse primitive types and strings using regular expressions

quoted from the official website, most websites took it and non of them said what a scanner is in english

Let me illustrate.

I have 3 views, a Button , EditText , TextView . I wanted to take the text from the EditView and put it in the TextView and I have 2 approaches, my question is what is the difference between them.

ALL THIS CODE GOES INTO THE ONCLICK LISTENER.

 Scanner sc = new Scanner(editText.getText().toString());
 String a = sc.next();
 txv.setText(a);

and this txv.setText(editText.getText().toString());

I got the data and it worked exactly the same in both cases and I can't seem to find anything useful.

Answer 1

You shouldn't be using Scanner here, you should be using StringTokenizer, or just split("\\\\s+")[0] on the string.

But sc.next() will read the first consecutive non-whitespace characters of the Scanner's input string into the variable a , which gets set to the next textview.

For example

Scanner sc = new Scanner("hello world");
String s = sc.next(); // == "hello"

---

Otherwise, in CLI applications Scanner is used for interactive inputs. Doesn't have much other use cases in production code that I can think of. Even for reading files, BufferedReader or the NIO API would be preferred