Scratch to Java (Part-1)

Transitioning from block coding to text can be challenging. In this post, we’ll look into the 1:1 code comparison of Scratch and Java. In the next post, we’ll take a Scratch project and code it in Java.

Common challenges of transitioning from Scratch to Java:

• All code blocks are visible on Scratch. However, for Java, students will have to look up the Java syntax and commands from documentation websites or by searching online. 
• Scratch doesn’t produce syntax errors. Java on the other hand has strict syntax rules and the wrong syntax will result in errors.
• Scratch produces visual results and animations. Students may find Java less engaging at first. 

Block-based program
High-level program (Java)	class Triangle {      …      double area(float  b, float h)      { return b*h/2;    }      …  }
Low-level program	LOAD r1, b LOAD r2, h MUL r1, r2 DIV r1, #2 RET
Executable Machine code	0000100101010001010001010 1000101010000110101001100 0101001000100010010101000 1010001010100010101000…

Scratch to Java Code Examples

Output

System.out.println("Hello World!");

Instantiating a variable

int a = 5; int b = 3;

Operators

int a = 5; int b = 3; System.out.println(a + b);

Conditional Statements

if (a > 50) { System.out.println("Great!"); }else{ System.out.println("Try again!"); }

For loop

int a = 0; for (int i = 0; i < 3; i++){ a = a + 1; }

Getting user input

import java.util.Scanner; public class Test { public static void main(String[] args){ Scanner scanObj = new Scanner(System.in); System.out.println("What's your name?"); String name = scanObj.nextLine(); System.out.println("Hi "+ name); } }

Function and function call

public static void main(String[] args){ hello("Julia"); } public static void hello(String name){ System.out.println("Hello " + name); }

Related Links:

• Scratch to Java Part-2
• FTCE Prep course