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1 Answer
Simon Coates
28,694 PointsIf it isn't handled immediately, it jumps up the call stack, until it finds code to handle it (a try/catch for the appropriate exception). I don't think you need to know the terminology, just how exceptions behave.
If methodOne called methodTwo, and methodTwo calls methodThree, then an exception in methodThree will bubble up to methodTwo unless it's handled. If methodTwo doesn't handle it, it will bubble up to methodOne. So you have options on where to handle the exception (methodTwo or methodOne), or whether you want to handle it in multiple places (catch, attempt partial recovery and rethrow it so that the calling method is notified).
case 1: CRASHES WHOLE APP
class Main {
public static void main(String[] args) {
methodOne();
System.out.println("I will not run");
}
public static void methodOne() {
methodTwo();
System.out.println("I will not run");
}
public static void methodTwo() {
methodThree();
System.out.println("I will not run");
}
public static void methodThree() {
String shortString = "a";
shortString.charAt(45); //causes an exception
}
}
case2: Handle exception at a higher level
class Main {
public static void main(String[] args) {
methodOne();
System.out.println("I will run");
}
public static void methodOne() {
try {
methodTwo();
System.out.println("I will not run");
} catch(StringIndexOutOfBoundsException e){
System.out.println("Run code to recover from exception");
}
}
public static void methodTwo() {
methodThree();
System.out.println("I will not run");
}
public static void methodThree() {
String shortString = "a";
shortString.charAt(45); //causes an exception
}
}
Case 3: Handle, throw and Rehandle
class Main {
public static void main(String[] args) {
try {
methodOne();
System.out.println("I will not run");
} catch(Exception e){
System.out.println("Run code to recover from exception");
}
}
public static void methodOne() throws Exception {
try {
methodTwo();
System.out.println("I will not run");
} catch(StringIndexOutOfBoundsException e){
System.out.println("Run code to recover from exception and rethrow");
throw e;
}
}
public static void methodTwo() {
methodThree();
System.out.println("I will not run");
}
public static void methodThree() {
String shortString = "a";
shortString.charAt(45); //causes an exception
}
}