JAVA PROGRAM • LEVEL 01 — BASICS & INPUT/OUTPUT
Read Input with BufferedReader in Java
Learn read input with bufferedreader in java with a complete, compiler-ready Java 17 example.
PROBLEM UNDERSTANDING
Input and expected output
7
49
COMPLETE JAVA 17 PROGRAM
Complete Java 17 implementation
class Main {
public static void main(String[] args) throws Exception {
java.io.BufferedReader reader = new java.io.BufferedReader(new java.io.InputStreamReader(System.in));
int number = Integer.parseInt(reader.readLine());
System.out.println(number * number);
}
}CURRENT STEP
Select Start to walk through the important lines.
SELECTED LINE
No line selected
EXPECTED OUTPUT FOR THE SAMPLE
49
PROGRAM EXPLANATION
Algorithm and explanation
- Read the sample input and convert it into the Java values required for read input with bufferedreader in java.
- Apply BufferedReader and Integer.parseInt() in the order shown by the program.
- Print the final result and compare it with the documented sample output.
This Java 17 example demonstrates BufferedReader and Integer.parseInt() through a complete, executable program. The values are intentionally small so students can trace each statement, verify the output, and then modify the example safely in the online compiler.
EFFICIENCY
Time and space complexity
O(1)
O(1)
DEBUGGING CHECKLIST
Common mistakes
Keep the class name Main and the entry method signature public static void main(String[] args) when using the online compiler.
Use BufferedReader with compatible Java types; Java checks types and method signatures at compile time.
Java is case-sensitive, and every statement that requires a semicolon must end with one.