this.keyword = keyword;

MyThisTest.java

public class MyThisTest {

  private int a;

  public MyThisTest() {
    this(42); // calls the other constructor
  }

  public MyThisTest(int a) {
    this.a = a; // assigns the value of the parameter a to the field of the same name
  }

  public void frobnicate() {
    int a = 1; // refers to the local variabla a

    System.out.println("Local variable a = " + a); // refers to the local variable a
    System.out.println("This field a = " + this.a); // refers to the field a
    System.out.println(this + "\n"); // refers to this entire object
  }

  @Override
  public String toString() {
    return "This entire object a = " + a; // refers to the field a
  }
}

MyThisTestTest.java

import java.util.Random;
import java.util.Scanner;

public class MyThisTestTest{
    public static void main(String[] args){
        MyThisTest test1 = new MyThisTest();
        test1.frobnicate();
        
        Scanner scanner = new Scanner(System.in);
        System.out.print("Enter a number: ");
        String userInput = scanner.nextLine();
        int a = 27;
        if (!userInput.equals("")){
            a = Integer.parseInt(userInput);
        } else {
            System.out.println("OK, random it is.");
            Random random = new Random();
            a = random.nextInt(99);
        }
        MyThisTest test2 = new MyThisTest(a);
        test2.frobnicate();
    }
}