Java Questions and Answers
FAQ
Copyright © Tony Morris 2005, 2006
Category: FAQ
FAQ #1
Where can I download the Sun Java Development Kit (JDK) or the Java Runtime Environment (JRE)?
Category: FAQ
FAQ #2
What is the difference between the Java Development Kit (JDK) and the Java Software Development Kit (SDK)?
Category: FAQ
FAQ #3
What is Java 2 Standard Edition? I hear of these other version names 1.1, 1.2, 1.3, 1.4, 1.5 alongside. Where did the 2 come from in Java 2?
Category: FAQ
FAQ #4
Do I want the Java Development Kit or the Java Runtime Environment?
Category: FAQ
FAQ #5
I have downloaded the JDK and I want to develop my own Java application. Where do I start?
Category: FAQ
FAQ #6
How do I install the Java Development Kit (JDK) or the Java Runtime Environment (JRE)?
Category: FAQ
FAQ #7
How do I set the PATH environment variable?
Category: FAQ
FAQ #8
How do I set the CLASSPATH environment variable?
Category: FAQ
FAQ #9
What is the Java 2 Standard Edition API Specification (aka Javadoc)?
Category: FAQ
FAQ #10
What does this mean 'Exception in thread "main" java.lang.NullPointerException'?
Category: FAQ
FAQ #11
What does this mean 'Exception in Thread "main" java.lang.NoClassDefFoundError <something>'?
Category: FAQ
FAQ #12
What does this mean 'variable <something> might not have been initialized'?
Category: FAQ
FAQ #13
What does this mean 'unreported exception <something>; must be caught or declared to be thrown'?
Category: FAQ
FAQ #14
What does this mean 'Note: <something> uses or overrides a deprecated API. Note: Recompile with -deprecation for details.'?
Category: FAQ
FAQ #15
How do I generate a random number between x and y?
Category: FAQ
FAQ #16
What is method overloading?
Category: FAQ
FAQ #17
Is the latest version of Java 1.5 or 5.0?
Category: FAQ
FAQ #18
What is method overriding?
Category: FAQ
FAQ #19
Can static methods be overridden?
Category: FAQ
FAQ #20
Does Java pass method parameters by reference, by value, both or neither?
Category: FAQ
FAQ #21
Can Java applications leak memory?
Category: FAQ
FAQ #22
Can I invoke the garbage collector?
Category: FAQ
FAQ #23
Can I convert my Java application into a Windows executable (.exe)?
Category: FAQ
FAQ #24
How do I convert a .class file back to a .java source file?
Category: FAQ
FAQ #25
How do I clear the console screen?
Category: FAQ
FAQ #26
How do I create a
String that represents a double (or float) value with only 2 decimal places?
Category: FAQ
FAQ #27
Does Java support multiple inheritance?
Category: FAQ
FAQ #28
How do I make a
javax.swing.JTextArea scroll to the end?
Category: FAQ
FAQ #29
Can I execute a system command?
Category: FAQ
FAQ #30
Can I reference the subclass from a superclass?
Category: FAQ
FAQ #31
Is it possible to prevent a thread of execution from executing for a specified period of time?
Category: FAQ
FAQ #32
Why shouldn't an Integrated Development Environment (IDE) be used for learning Java?
Category: FAQ
FAQ #33
When should I use java.util.Vector/java.util.Hashtable?
Category: FAQ
FAQ #34
Is it possible to increase efficiency by using less import statements?
Category: FAQ
FAQ #35
Can I start my
java.lang.Thread more than once?
Category: FAQ
FAQ #36
What's the difference between javaw.exe and java.exe?
Category: FAQ
FAQ #37
How do I exit my application?
Category: FAQ
FAQ #38
Why is my GUI application broken if I set the layout to null?
Category: FAQ
FAQ #39
Why shouldn't I use floating-point types for representing monetary values (or any value that demands accuracy)?
Category: FAQ
FAQ #40
What's the difference between Java and J++ and J# and Javascript?
Category: FAQ
FAQ #41
How do I access an outer class member/method from an inner class?
Category: FAQ
FAQ #42
What is the newline character?
Category: FAQ
FAQ #43
Does Java support multi-dimensional arrays?
Category: FAQ
FAQ #44
What is the difference between a nested class, an inner class, a local class, an anonymous class and a member class (or interface)?
Category: FAQ
FAQ #45
Are String constants objects? If so, are they garbage collected?
Category: FAQ
FAQ #46
What do I see the following compiler warning?
Note: <something>.java uses unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.
Category: FAQ
FAQ #47
How do I create a splash screen (or a peerless window) for my application?
Category: FAQ
FAQ #48
How do I convert a String to a primitive type?
Category: FAQ
FAQ #49
Is it JAVA, java or Java?
Category: FAQ
FAQ #50
What is the difference between an object and an object reference?
Category: FAQ
FAQ #51
How can I invoke the Constructor.newInstance method without generating a compile-time warning when using -source 1.5?