Console input using character streams

To read console data in Java efficiently and in a character-friendly way (ideal for internationalization), it is recommended to use character streams instead of byte streams. Since System.in is a stream of bytes, it must be encapsulated in a Reader. The recommended class for this task is BufferedReader, which uses InputStreamReader to convert bytes to characters.

The process works as follows:

Create an InputStreamReader associated with System.in:

InputStreamReader fluxoEntrada = new InputStreamReader(System.in);

Then pass this InputStreamReader to the BufferedReader constructor:

BufferedReader br = new BufferedReader(fluxoEntrada);

This way, br is a character-based input stream connected to the console.

Methods for reading characters and strings

• read(): Reads a single Unicode character and returns -1 at the end of the stream.
• readLine(): Reads a complete line as a String until the user presses ENTER, returning null at the end of the stream.

Example of use:
The following code reads characters from the console up to the character . be typed:

char c;
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
System.out.println("Enter characters, period to quit.");
do {
  c = (char) br.read();
  System.out.println(c);
} while(c != '.');

Another example allows you to read lines of text until the word "stop" is inserted:

String str;
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
System.out.println("Enter lines of text.");
System.out.println("Enter 'stop' to quit.");
do {
  str = br.readLine();
  System.out.println(str);
} while(!str.equals("stop"));

These approaches make keyboard data entry more convenient and structured, especially for programs that require support for different character encodings.

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