I still remember the first time one of my Java programs stopped dead with a red message saying ArrayIndexOutOfBoundsException. It was a loop going through an array of grades, and I was convinced the code was perfect: I had written i <= grades.length. I came from Python, where a mistake like that would have given…
My first method with an if / else if gave me missing return statement, and I spent a good while staring at it, because to me the two conditions covered every case: either it’s greater than or equal to 5, or it’s less than 5. What else is there? Turns out the compiler doesn’t do…
My first program with methods was a calculator where I had written every operation inside main… and then, when I added subtraction, I copy-pasted the addition block and just changed the sign. When I wanted to change how decimals were displayed, I had to edit it in four places, and I forgot one. That’s when…
The first time I saw a method in Java, I remember staring at the first line before even understanding what the method did: public static int calculateAverage(int a, int b). In Python, a function starts with def and that’s it. Here there were four words before even reaching the name, and each one seemed to…
When I wrote my first nested loop, it froze. It wasn’t an infinite loop from forgetting the condition — I had that part under control — it was that I updated the outer loop’s counter inside the inner loop, so the outer one never moved forward. I had to force-close the terminal. If something similar…
There’s an FP2 lab exercise that looks trivial until you actually try it: counting how many vowels a sentence has. In Python it was for c in text: and that’s it, no further thought needed. In Java, the first thing you instinctively write is for (char c : text), and the compiler throws back an…
In the practice you combined Scanner, if/else and switch in programs that looked like real things. Now it’s your turn to solve on your own. All three exercises circle back to the same idea you already saw: validating input, making decisions based on several conditions and controlling a loop that depends on what the user…
There’s a very specific moment in the FP2 lab that almost everyone goes through the same way. You’ve spent half an hour on a program that asks for several pieces of input, everything compiles, everything looks fine… and suddenly the program skips a question. No error. It just carries on as if you had already…
In the practice article we deliberately triggered the three classic variable surprises in Java. Now it’s time to solve on your own — but with a twist: the exercises here won’t focus on exactly the same things as the practice. Integer division, casting and == will appear, but as tools to solve something, not as…
There’s a moment in the first Java lab that happens to almost everyone. You’ve been writing code for a while, you get to a division, you run the program and the result is… 3. Not 3.5. Not 3.33. Three. A whole number. The number you expected was right there on paper, but Java decided to…