public class Main { public static void main(String[] args) { try (BufferedReader br = new BufferedReader(new InputStreamReader(System.in))) { String input = br.readLine(); System.out.print("Input…

Question

Options

• ASystem.out is the standard output stream. The stream is open only when System.out is called
• BSystem.in cannot reassign the other stream.
• CSystem.err is printstream and java.OutputStream by default.
• DSystem.in is the standard input stream. The stream is already open.

• A
  8% (3)
• B
  14% (5)
• C
  6% (2)
• D
  72% (26)

Explanation

System.in is a static field of the java.lang.System class representing the standard input stream - it is always open from JVM startup, which is why wrapping it in a BufferedReader works immediately without any explicit open call, as the code demonstrates.

Why the distractors are wrong:

• A is false because System.out is always open too - it's not opened on-demand when called; it's a pre-opened PrintStream available from JVM startup.
• B is false because System.in can be reassigned using System.setIn(InputStream), which replaces the standard input with another stream.
• C is partially misleading - System.err is indeed a PrintStream, but PrintStream extends FilterOutputStream which extends OutputStream, not java.io.OutputStream directly as a separate interface; more importantly, the phrasing "by default" is vague and the statement conflates inheritance with instantiation in a way that makes it incorrect as written.

Memory tip: Think of the three standard streams (System.in, System.out, System.err) as always-on pipes - they're wired up before your main method runs and stay open for the JVM's lifetime, just like stdin/stdout/stderr in any Unix process.

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