An exception is an object that signals a runtime error and interrupts the normal flow. You handle it with try / catch / finally and raise it with throw. Checked exceptions (Exception) must be declared or handled; unchecked ones (RuntimeException) do not require it. Do not swallow them silently.
Example
try {
Integer.parseInt(texte);
} catch (NumberFormatException e) {
System.out.println("Invalid number");
}