Answer: TreeSet and class hierarchy : Questions « Utility Classes « SCJP

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8.31.12.Answer: TreeSet and class hierarchy
Exception in thread "main" java.lang.ClassCastException: Dog cannot be cast to java.lang.Comparable
	at java.util.TreeMap.put(TreeMap.java:542)
	at java.util.TreeSet.add(TreeSet.java:238)
	at MainClass.main(MainClass.java:17)
8.31.Questions
8.31.1.Which collection allows you to grow or shrink its size and provides indexed access to its elements, but whose methods are not synchronized?
8.31.2.Answer: collection
8.31.3.What is the result(PriorityQueue)?
8.31.4.Answer: PriorityQueue
8.31.5.What is the output(TreeSet and sub set)?
8.31.6.Answer: TreeSet and sub set
8.31.7.What is the output(TreeMap and ceiling keys)?
8.31.8.Answer: TreeMap and ceiling keys
8.31.9.Which, inserted independently at line 9, will compile? (Choose all that apply.)
8.31.10.Answer: generic and hierarchy
8.31.11.What is the result(TreeSet)?
8.31.12.Answer: TreeSet and class hierarchy
8.31.13.What is the output(implements Comparator)?
8.31.14.Answer: implements Comparator
8.31.15.Instances of which class(es) can be serialized?
8.31.16.Answer: serizlizable objects
8.31.17.What is the output(NumberFormat)?
8.31.18.Answer: NumberFormat
8.31.19.What is the result(pattern matching)?
8.31.20.Answer: pattern matching
8.31.21.What is the result(Scanner)?
8.31.22.Answer: Scanner
8.31.23.Which of the following suggested changes will allow the method to compile?
8.31.24.Answer: Boolean and if statement
8.31.25.You must initialize java.lang.System class if you want to use the System.err output(True/False).
8.31.26.Answer: java.lang.System
8.31.27.The System.arraycopy method works only with arrays of primitives(True/False).
8.31.28.Answer: System.arraycopy method
8.31.29.The System.exit method takes an int primitive parameter(True/False).
8.31.30.Answer: System.exit method
8.31.31.There is a Runtime method to request that the JVM start garbage collection(True/False).
8.31.32.Answer: Runtime method
8.31.33.long avail = Runtime.getRuntime().freeMemory() returns the approximate amount of free memory available to the JVM(True/False)
8.31.34.Answer: Runtime.getRuntime().freeMemory()
8.31.35.A Vector can hold object references or primitive values(True/False).
8.31.36.Answer: Vector and primitive values
8.31.37.A Vector maintains object references in the order they were added(True/False).
8.31.38.Answer: Vector and inserted order
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