You can put an if
statement inside another if
statement.
This code is correctly indented, but ugly and hard to read. It also can go very far to the right if there are many tests.
if (score < 35) g.setColor(Color.magenta); else if (score < 50) g.setColor(Color.red); else if (score < 60) g.setColor(Color.orange); else if (score < 80) g.setColor(Color.yellow); else g.setColor(Color.green);
If you use braces, there is no problem with deciding which
else
goes with which if
For example,
if (age < 24) { if (height > 200) { c = Color.red; } } else { c = Color.blue; }
Because the true and false parts are both single statements, you might want to leave out the braces and write:
if (age < 24) if (height > 200) c = Color.red; else // DANGER: which 'if' goes with this 'else' c = Color.blue;
But this is WRONG, because 'else' always goes with the nearest 'if' when there are no braces. This code is the same as:
if (age < 24) { if (height > 200) c = Color.red; else c = Color.blue; }
if
statementsThese kinds of errors are very hard to find. This is another good reason to always use braces.
Why does the following code always say it thinks the user is lying?
String ageStr = JOptionPane.showInputDialog(null, "How old are you?"); int age = Integer.parseInt(ageStr); if (age > 120 || age < 0); System.out.println("I think you're lying about your age!");
It's the semicolon! if you put a semicolon directly after the condition
in an if
statement, Java thinks it's finished with the body
of the statement. The indentation of the next line, which is so important
to human readers, is ignored by Java.
This is another error that's harder to make if you always follow the condition by an opening brace.