Method calling in Java - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to call the method greet.

Java

public class Main {
    public static void greet() {
        System.out.println("Hello!");
    }
    public static void main(String[] args) {
        [1];
    }
}

Drag options to blanks, or click blank then click option'

Agreet()

Bgreet

Ccall greet()

DSystem.greet()

Attempts:

3 left

💡 Hint

Common Mistakes

Forgetting the parentheses when calling the method.

Trying to call the method with System.greet() which is incorrect here.

To call a method in Java, you use its name followed by parentheses, like greet().

2fill in blank

medium

Complete the code to call the method add with arguments 5 and 3.

Java

public class Calculator {
    public static int add(int a, int b) {
        return a + b;
    }
    public static void main(String[] args) {
        int result = [1];
        System.out.println(result);
    }
}

Drag options to blanks, or click blank then click option'

Aadd{5, 3}

Badd 5, 3

Cadd[5, 3]

Dadd(5, 3)

Attempts:

3 left

💡 Hint

Common Mistakes

Using square brackets or curly braces instead of parentheses.

Omitting parentheses around the arguments.

To call a method with arguments, use the method name followed by parentheses enclosing the arguments separated by commas.

3fill in blank

hard

Fix the error in calling the method printMessage.

Java

public class Messenger {
    public static void printMessage(String msg) {
        System.out.println(msg);
    }
    public static void main(String[] args) {
        [1];
    }
}

Drag options to blanks, or click blank then click option'

AprintMessage{Hello World}

BprintMessage("Hello World")

CprintMessage['Hello World']

DprintMessage msg

Attempts:

3 left

💡 Hint

Common Mistakes

Using spaces instead of parentheses for arguments.

Using square or curly brackets instead of parentheses.

Not quoting the string argument.

Method calls require parentheses around arguments. Use printMessage("Hello World") to pass the string argument.

4fill in blank

hard

Fill both blanks to call the method multiply with arguments 4 and 7 and store the result.

Java

public class MathOps {
    public static int multiply(int x, int y) {
        return x * y;
    }
    public static void main(String[] args) {
        int product = [1];
        System.out.println([2]);
    }
}

Drag options to blanks, or click blank then click option'

Amultiply(4, 7)

Bmultiply(7, 4)

Cproduct

Dx * y

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping arguments in the method call.

Printing the method call instead of the stored variable.

Call multiply(4, 7) to get the product, then print the variable product.

5fill in blank

hard

Fill all three blanks to call concat method with two strings and print the result.

Java

public class StringOps {
    public static String concat(String a, String b) {
        return a + b;
    }
    public static void main(String[] args) {
        String result = [1];
        System.out.println([2]);
        System.out.println([3]);
    }
}

Drag options to blanks, or click blank then click option'

Aconcat("Hello, ", "World!")

Bresult

C"Done"

Dconcat("Hi", " there")

Attempts:

3 left

💡 Hint

Common Mistakes

Not using quotes around string arguments.

Printing the method call instead of the stored variable.

Forgetting to print the final "Done" string.

Call concat with two strings to get result, print result, then print "Done".

Practice

1. What does calling a method in Java do?
myMethod();

easy

A. Runs the instructions inside the method named myMethod.

B. Creates a new method called myMethod.

C. Deletes the method myMethod from the program.

D. Prints the name myMethod on the screen.

Solution

1. Step 1: Understand what a method call does

   Calling a method means running the code inside that method.

2. Step 2: Analyze the example myMethod();

   This runs the instructions saved inside the method named myMethod.

3. Final Answer:

   Runs the instructions inside the method named myMethod. -> Option A

4. Quick Check:

   Method call = run method code [OK]

Hint: Method call runs code inside method name() [OK]

Common Mistakes:

• Thinking method call creates or deletes methods
• Confusing method call with printing text
• Assuming method call changes method definition

2. Which of the following is the correct way to call a method named displayMessage in Java?

easy

A. run displayMessage();

B. call displayMessage();

C. displayMessage;

D. displayMessage();

Solution

1. Step 1: Recall Java method call syntax

   In Java, you call a method by writing its name followed by parentheses.

2. Step 2: Check each option

   Only displayMessage(); matches the correct syntax for calling a method.

3. Final Answer:

   displayMessage(); -> Option D

4. Quick Check:

   Method call syntax = name() [OK]

Hint: Method call needs parentheses after name [OK]

Common Mistakes:

• Omitting parentheses when calling methods
• Adding extra words like 'call' or 'run'
• Using semicolon without parentheses

3. What is the output of this Java code?

public class Test {
  public static void sayHi() {
    System.out.println("Hi there!");
  }
  public static void main(String[] args) {
    sayHi();
  }
}

medium

A. sayHi()

B. No output

C. Hi there!

D. Compilation error

Solution

1. Step 1: Identify the method call in main

   The main method calls sayHi(), which prints "Hi there!".

2. Step 2: Understand what sayHi() does

   It prints the text "Hi there!" to the screen.

3. Final Answer:

   Hi there! -> Option C

4. Quick Check:

   Method prints text = output text [OK]

Hint: Method prints text, so output is printed string [OK]

Common Mistakes:

• Confusing method name with output
• Expecting no output without print statement
• Thinking method call causes error

4. Find the error in this Java code snippet:

public class Demo {
  public static void greet() {
    System.out.println("Hello!");
  }
  public static void main(String[] args) {
    greet;
  }
}

medium

A. Incorrect method name.

B. Missing parentheses when calling method greet.

C. Missing semicolon after greet.

D. Method greet is not defined.

Solution

1. Step 1: Check method call syntax in main

   The code uses greet; which is missing parentheses.

2. Step 2: Understand correct method call

   Method calls require parentheses even if no arguments: greet();.

3. Final Answer:

   Missing parentheses when calling method greet. -> Option B

4. Quick Check:

   Method call needs () [OK]

Hint: Always use () to call methods, even if empty [OK]

Common Mistakes:

• Forgetting parentheses on method calls
• Thinking semicolon alone calls method
• Assuming method call without () is valid

5. Given this Java code:

public class Calculator {
  public static int add(int a, int b) {
    return a + b;
  }
  public static void main(String[] args) {
    int result = add(5, 3);
    System.out.println(result);
  }
}

What will be printed when the program runs?

hard

A. 8

B. 53

C. add(5, 3)

D. Compilation error

Solution

1. Step 1: Understand method add parameters and return

   The method add takes two integers and returns their sum.

2. Step 2: Analyze the call add(5, 3)

   It returns 5 + 3 = 8, which is stored in result.

3. Step 3: Check the output statement

   System.out.println(result); prints the value 8.

4. Final Answer:

   8 -> Option A

5. Quick Check:

   Sum of 5 and 3 = 8 [OK]

Hint: Method returns sum; print shows result [OK]

Common Mistakes:

• Concatenating numbers as strings instead of adding
• Expecting method name printed instead of result
• Confusing return value with method call syntax