OnJava8-Examples/exceptions/StormyInning.java at master · CSapprenticeWT/OnJava8-Examples · GitHub

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// exceptions/StormyInning.java

// We make no guarantees that this code is fit for any purpose.

// Visit http://OnJava8.com for more book information.

// Overridden methods can throw only the exceptions

// specified in their base-class versions, or exceptions

// derived from the base-class exceptions

class BaseballException extends Exception {}

class Foul extends BaseballException {}

class Strike extends BaseballException {}

abstract class Inning {

Inning() throws BaseballException {}

public void event() throws BaseballException {

// Doesn't actually have to throw anything

}

public abstract void atBat() throws Strike, Foul;

public void walk() {} // Throws no checked exceptions

}

class StormException extends Exception {}

class RainedOut extends StormException {}

class PopFoul extends Foul {}

interface Storm {

void event() throws RainedOut;

void rainHard() throws RainedOut;

}

public

class StormyInning extends Inning implements Storm {

// OK to add new exceptions for constructors, but you

// must deal with the base constructor exceptions:

public StormyInning()

throws RainedOut, BaseballException {}

public StormyInning(String s)

throws BaseballException {}

// Regular methods must conform to base class:

//- void walk() throws PopFoul {} //Compile error

// Interface CANNOT add exceptions to existing

// methods from the base class:

//- public void event() throws RainedOut {}

// If the method doesn't already exist in the

// base class, the exception is OK:

@Override public void rainHard() throws RainedOut {}

// You can choose to not throw any exceptions,

// even if the base version does:

@Override public void event() {}

// Overridden methods can throw inherited exceptions:

@Override public void atBat() throws PopFoul {}

public static void main(String[] args) {

try {

StormyInning si = new StormyInning();

si.atBat();

} catch(PopFoul e) {

System.out.println("Pop foul");

} catch(RainedOut e) {

System.out.println("Rained out");

} catch(BaseballException e) {

System.out.println("Generic baseball exception");

}

// Strike not thrown in derived version.

try {

// What happens if you upcast?

Inning i = new StormyInning();

i.atBat();

// You must catch the exceptions from the

// base-class version of the method:

} catch(Strike e) {

System.out.println("Strike");

} catch(Foul e) {

System.out.println("Foul");

} catch(RainedOut e) {

System.out.println("Rained out");

} catch(BaseballException e) {

System.out.println("Generic baseball exception");

}

OnJava8-Examples/exceptions/StormyInning.java at master · CSapprenticeWT/OnJava8-Examples · GitHub

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