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.

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.

Level of Abstraction

Block-based program
High-level program (Java)class Triangle {
     ‚Ķ
     double area(float  b, float h)
     { return b*h/2;    }
     ...
 }
Low-level programLOAD r1, b
LOAD r2, h
MUL r1, r2
DIV r1, #2
RET
Executable Machine code0000100101010001010001010
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); 
}

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