| Displaying Page (3) of (5) | Total FAQ's Found : (135) |
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| 61) | Is a class a subclass of itself? |
| | A class is a subclass of itself. |
| 62) | What is the highest-level event class of the event-delegation model? |
| | The java.util.EventObject class is the highest-level class in the event-delegation class hierarchy.
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| 63) | What event results from the clicking of a button? |
| | The ActionEvent event is generated as the result of the clicking of a button. |
| 64) | How can a GUI component handle its own events? |
| | A component can handle its own events by implementing the required event-listener interface and adding itself as its own event listener.
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| 65) | How are the elements of a GridBagLayout organized? |
| | The elements of a GridBagLayout are organized according to a grid. However, the elements are of different sizes and may occupy more than one row or column of the grid. In addition, the rows and columns may have different sizes. |
| 66) | What advantage do Java's layout managers provide over traditional windowing systems? |
| | Java uses layout managers to lay out components in a consistent manner across all windowing platforms. Since Java's layout managers aren't tied to absolute sizing and positioning, they are able to accomodate platform-specific differences among windowing systems.
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| 67) | What is the Collection interface? |
| | The Collection interface provides support for the implementation of a mathematical bag - an unordered collection of objects that may contain duplicates.
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| 68) | What modifiers can be used with a local inner class? |
| | A local inner class may be final or abstract.
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| 69) | What is the difference between static and non-static variables? |
| | A static variable is associated with the class as a whole rather than with specific instances of a class. Non-static variables take on unique values with each object instance. |
| 70) | What is the difference between the paint and repaint methods? |
| | The paint method supports painting via a Graphics object. The repaint method is used to cause paint to be invoked by the AWT painting thread.
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| 71) | What is the purpose of the File class? |
| | The File class is used to create objects that provide access to the files and directories of a local file system. |
| 72) | Can an exception be rethrown? |
| | Yes, an exception can be rethrown. |
| 73) | Which Math method is used to calculate the absolute value of a number? |
| | The abs method is used to calculate absolute values. |
| 74) | How does multithreading take place on a computer with a single CPU? |
| | The operating system's task scheduler allocates execution time to multiple tasks. By quickly switching between executing tasks, it creates the impression that tasks execute sequentially. |
| 75) | When does the compiler supply a default constructor for a class? |
| | The compiler supplies a default constructor for a class if no other constructors are provided. |
| 76) | When is the finally clause of a try-catch-finally statement executed? |
| | The finally clause of the try-catch-finally statement is always executed unless the thread of execution terminates or an exception occurs within the execution of the finally clause.
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| 77) | Which class is the immediate superclass of the Container class? |
| | Component |
| 78) | If a method is declared as protected, where may the method be accessed? |
| | A protected method may only be accessed by classes or interfaces of the same package or by subclasses of the class in which it is declared.
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| 79) | How can the Checkbox class be used to create a radio button? |
| | By associating Checkbox objects with a CheckboxGroup.
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| 80) | Which non-Unicode letter characters may be used as the first character of an identifier? |
| | The non-Unicode letter characters $ and _ may appear as the first character of an identifier.
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| 81) | What restrictions are placed on method overloading? |
| | Two methods may not have the same name and argument list but different return types. |
| 82) | What happens when you invoke a thread's interrupt method while it is sleeping or waiting? |
| | When a task's interrupt method is executed, the task enters the ready state. The next time the task enters the running state, an InterruptedException is thrown.
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| 83) | What is casting? |
| | There are two types of casting, casting between primitive numeric types and casting between object references. Casting between numeric types is used to convert larger values, such as double values, to smaller values, such as byte values. Casting between object references is used to refer to an object by a compatible class, interface, or array type reference.
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| 84) | What is the return type of a program's main method? |
| | A program's main method has a void return type. |
| 85) | What is the difference between a field variable and a local variable? |
| | A field variable is a variable that is declared as a member of a class. A local variable is a variable that is declared local to a method.
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| 86) | Under what conditions is an object's finalize method invoked by the garbage collector? |
| | The garbage collector invokes an object's finalize method when it detects that the object has become unreachable. |
| 87) | How are this and super used with constructors? |
| | this is used to invoke a constructor of the same class. super is used to invoke a superclass constructor.
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| 88) | What is the relationship between a method's throws clause and the exceptions that can be thrown during the method's execution? |
| | A method's throws clause must declare any checked exceptions that are not caught within the body of the method. |
| 89) | What is the difference between the JDK 1.02 event model and the event-delegation model introduced with JDK 1.1? |
| | The JDK 1.02 event model uses an event inheritance or bubbling approach. In this model, components are required to handle their own events. If they do not handle a particular event, the event is inherited by or bubbled up to the component's container. The container then either handles the event or it is bubbled up to its container and so on, until the highest-level container has been tried..
In the event-delegation model, specific objects are designated as event handlers for GUI components. These objects implement event-listener interfaces. The event-delegation model is more efficient than the event-inheritance model because it eliminates the processing required to support the bubbling of unhandled events.
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| 90) | How is it possible for two String objects with identical values not to be equal under the == operator? |
| | The == operator compares two objects to determine if they are the same object in memory. It is possible for two String objects to have the same value, but located indifferent areas of memory.
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