Yarixxx Голосов: 1 Адрес блога: http://y3x.ru Добавлен: 2010-12-17 00:20:50 блограйдером yarix

ClassCastException on Queue

2015-06-15 19:29:27 (читать в оригинале)

ClassCastException happens when we are trying to add element which cannot be casted to intended type. Here is a simple code which leads to ClassCastException. Queue q = new ArrayBlockingQueue(3); Object s = "a"; System.out.println(q.offer((Integer)s)); it throws exception which starts with the following stacktrace. java.lang.ClassCastException: java.lang.String cannot be cast to java.lang.Integer

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Java Predicates

2015-06-15 18:48:26 (читать в оригинале)

There is a useful class in Java Collections: Predicate. It allows to validate verify elements. The following Predicate checks if String is shorter than 3 letters: Predicate LINES_SHORTER_THAN_3 = new Predicate() { @Override public boolean test(String s) { return s.length() < 3; } }; Another one checks if String starts with H letter. Predicate STARTS_WITH_H […]

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NoSuchElementException on Queue

2015-06-15 17:53:02 (читать в оригинале)

This exception could happen if queue is empty. System.out.println(q.remove(“4″)); In fact, my experience shows, that: Queue q = new PriorityQueue(2); System.out.println(q.remove()); will fail in the following way: java.util.NoSuchElementException at java.util.AbstractQueue.remove(AbstractQueue.java:117) ...

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NullPointerException on Queue

2015-06-15 17:40:51 (читать в оригинале)

Another experiment shows that attempt to add null to a queue: Queue q = new PriorityQueue(); System.out.println(q.add(null)); will throw NullPointerException: java.lang.NullPointerException at java.util.PriorityQueue.offer(PriorityQueue.java:335) at java.util.PriorityQueue.add(PriorityQueue.java:321) ...

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IllegalStateException on Queue

2015-06-15 17:36:30 (читать в оригинале)

My experiment shows that the following code: Queue q = new ArrayBlockingQueue(2); System.out.println(q.add(1)); System.out.println(q.add(2)); System.out.println(q.add(3)); will print true twice and then will fall down: java.lang.IllegalStateException: Queue full at java.util.AbstractQueue.add(AbstractQueue.java:98) at java.util.concurrent.ArrayBlockingQueue.add(ArrayBlockingQueue.java:312) ...