In this post I'll explain some syntactical differences between JavaScript and Java.

Declaring and assigning a variable

// JAVASCRIPTlet watermelon = "good";// JAVAString watermelon = "good";

In JavaScript, you can declare a variable withlet,const orvar. You do not need to specify the variable's data type, like you do in Java. In the Java example above, we need to say thewatermelon variable will point to theString,"good".

Printing/logging/outputting something

// JAVASCRIPTconsole.log("tomatoes are gross");// JAVASystem.out.println("tomatoes are gross");

There is just a minor difference between printing in JavaScript vs. Java. Printing the contents of an array works a bit differently in Java compared to JavaScript, which I'll cover later in this post.

Variable interpolation

// JAVASCRIPTlet fruit = "blueberry";console.log(`My favorite fruit is the ${fruit}`);// JAVAString fruit = "blueberry";System.out.println(  String.format("My favorite fruit is the %s", fruit));

To put a variable in a string:

• In JavaScript, inside theconsole.log, write your string with back ticks; insert${variableName} where you want your variable to go.

• In Java, inside theSystem.out.println, useString.format() to write your string; insert%s where you want your variable to go; after the ending quotation mark of the string, place a comma then write your variable name.

Declaring, invoking, and printing the return value of a function/method

// JAVASCRIPTconst isEven = (num) => {  // do something with num and return the result  return (num % 2 === 0) ? true : false;}console.log(isEven(4));// JAVApublic class Main {  static boolean isEven(int num) {    // do something with num and return the result    return (num % 2 == 0) ? true : false;  }  public static void main(String[] args) {    System.out.println(isEven(4));  }}

In both languages, we're passing an integer of4 to theisEven function/method. Then, we determine whether the remainder of the integer divided by 2 is 0. If it is, it's an even number so we returntrue; else, the integer is not even so we returnfalse.

In JavaScript, you can declare and invoke a function with the following general syntax:

// declare a function called functionNameconstfunctionName=(parameter1,parameter2,...)=>{// return something}// invoke the function called functionNamefunctionName(argument1,argument2,...);

However, in Java, every method needs to be declared within a class (in the above example, the class isMain). Every parameter to a method needs to have a data type. If the method returns something, you need to specify the return value's data type (void means nothing is returned). Every method must be invoked within themain method (The Java compiler will look for amain method before it executes any other code).

The following is the general syntax for declaring and invoking a method in Java:

publicclassMain{// declare a function called functionNamestaticreturnValueDataTypefunctionName(parameterOneDataTypeparameterOne,parameterTwoDataTypeparameterTwo,...){// return something}publicstaticvoidmain(String[]args){// invoke the function called functionNamefunctionName(argument1,argument2,...);}}

Declaring and printing an array

// #"strawberry", "orange", "lemon"];console.log(array);// JAVA:public class Main {  public static void main(String[] args) {    String[] array = {"strawberry", "orange", "lemon"};    for (int i = 0; i < array.length; i++) {      System.out.println(array[i]);    }  }}

In JavaScript, the elements in an array go inside of square [] brackets. In Java, the elements in an array go inside curly {} braces. Also in Java, you need to specify what data type the elements in the array will be. This is why we writeString[] above. TheString tells Java the array elements will beStrings. The[] tells Java you're creating an array.

Since Java doesn't natively print out the contents of an array withSystem.out.println(arrayName), you need to loop through the array, printing each element for each iteration. This is why the above example uses afor loop to print each element in the array.