JAVA PROGRAM • LEVEL 01 — BASICS & INPUT/OUTPUT
Read an Integer in Java
Learn read an integer in java with a complete, compiler-ready Java 17 example.
PROBLEM UNDERSTANDING
Input and expected output
42
Value = 42
COMPLETE JAVA 17 PROGRAM
Complete Java 17 implementation
class Main {
public static void main(String[] args) throws Exception {
java.util.Scanner input = new java.util.Scanner(System.in);
int value = input.nextInt();
System.out.println("Value = " + value);
}
}CURRENT STEP
Select Start to walk through the important lines.
SELECTED LINE
No line selected
EXPECTED OUTPUT FOR THE SAMPLE
Value = 42
PROGRAM EXPLANATION
Algorithm and explanation
- Read the sample input and convert it into the Java values required for read an integer in java.
- Apply Scanner and nextInt() in the order shown by the program.
- Print the final result and compare it with the documented sample output.
This Java 17 example demonstrates Scanner and nextInt() 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
Create one Scanner for System.in, read values in the documented order, and use the correct next... method for each type.
Use Scanner 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.