Given the contents of the Test.java file: class MyClass { private int var1 = 100; public int var2 = 200; public void doCalc() { var1 = 100 2; var2 = 200 2; } } public class Test { public static void…

The correct answer is C. A compilation error occurs at line n2. Option C is correct because var1 is declared private in MyClass, meaning it can only be accessed from within that class - attempting to read x.var1 directly in Test.main() (line n2) violates access control and causes a compilation error. Option A ("200 : 400") and D ("100…

Object-Oriented Programming Principles

Question

Given the contents of the Test.java file:
class MyClass {
private int var1 = 100;
public int var2 = 200;
public void doCalc() {
var1 = 100 * 2;
var2 = 200 * 2;
}
}
public class Test {
public static void main(String[] args) {
MyClass x = new MyClass();
x.doCalc();
System.out.println (x.var1 + " " + x.var2); // line n2
}
}
What is the result?

Options

A200 : 400
BA compilation error occurs at line n1.
CA compilation error occurs at line n2.
D100 : 400

How the community answered

(40 responses)

A
5% (2)
B
8% (3)
C
85% (34)
D
3% (1)

Explanation

Option C is correct because var1 is declared private in MyClass, meaning it can only be accessed from within that class - attempting to read x.var1 directly in Test.main() (line n2) violates access control and causes a compilation error.

Option A ("200 : 400") and D ("100 : 400") are wrong because the code never compiles in the first place - runtime output is impossible. Option B is wrong because doCalc() is public, so calling x.doCalc() is perfectly legal; no error occurs before line n2.

Memory tip: The rule is "private = class-only." If you see x.someField or x.someMethod() used outside the class where it's defined, ask yourself: "Is it private?" If yes, it's a compile-time error, not a runtime one.

Topics

#Access Modifiers#Private Keyword#Field Visibility#Encapsulation

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