String Concatenation and Console Output

Java reads an expression with + strictly left to right, and it decides what + means one operation at a time based on what it has built so far. If both operands at that step are numbers, + adds them. The moment one operand is a String, + concatenates: it turns the other operand into text and joins the characters. That decision doesn't reset partway through a line. Once a String enters the chain, every later + in that same expression concatenates, even if the operands after it look like numbers.

This is why int total = a + b; followed by System.out.println(total + " items"); still does real addition first. total is a plain int variable, computed and stored before println ever runs. Only inside the println call does the + meet a String, so that one addition becomes concatenation with the word items.

println and print both send text to the console, but println adds a line break afterward and print does not. Call print three times in a row and all three outputs sit glued together on one line; call println three times and each one starts fresh on its own line. This matters once you start chaining several output statements, since forgetting which one you used is a common source of console output that looks wrong even though the values themselves are correct.