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Do any JVM's JIT compilers generate code that uses vectorized floating point instructions?
Let's say the bottleneck of my Java program really is some tight loops to compute a bunch of vector dot products. Yes I've profiled, yes it's the bottleneck, yes it's significant, yes that's just how the algorithm is, yes I've run Proguard to optimize the byte code, etc.
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Any implementation of Ordered Set in Java?
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Take a look at LinkedHashSet class
From Java doc:
Hash table and linked list implementation of the Set interface, with predictable iteration order. This implementation differs from HashSet in that it maintains a doubly-linked list running through all of its entri...
What are .dex files in Android?
...l Machine (the workhorse under the Android system) is that it does not use Java bytecode. Instead, a homegrown format called DEX was introduced and not even the bytecode instructions are the same as Java bytecode instructions.
Compiled Android application code file.
Android programs are compiled...
Reverse a string in Java
...lder(hi).reverse().toString()
Or, for versions earlier than JDK 1.5, use java.util.StringBuffer instead of StringBuilder — they have the same API. Thanks commentators for pointing out that StringBuilder is preferred nowadays when there is no concurrency concern.
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Why would a static nested interface be used in Java?
...were public, or if the class were hand-assembled or compiled from some non-Java language, etc. The Java compiler, however, checks the access modifier on the enclosing class even when the resulting bytecode would not refer to that enclosing class.
– Jesse Glick
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Best way to convert an ArrayList to a string
...tring);
In fact, a string concatenation is going to be just fine, as the javac compiler will optimize the string concatenation as a series of append operations on a StringBuilder anyway. Here's a part of the disassembly of the bytecode from the for loop from the above program:
61: new #13; //...
Does java.util.List.isEmpty() check if the list itself is null? [duplicate]
Does java.util.List.isEmpty() check if the list itself is null , or do I have to do this check myself?
8 Answers
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Set environment variables on Mac OS X Lion
...ust add, one per line, the variable name and its value as follows:
export JAVA_HOME=/Library/Java/Home
export JRE_HOME=/Library/Java/Home
etc.
If you are modifying your "PATH" variable, be sure to include the system's default PATH that was already set for you:
export PATH=$PATH:/path/to/my/stuf...
Checking if a string is empty or null in Java [duplicate]
...tring which consists of spaces or special characters eg " " empty too. See java.lang.Character.isWhitespace API
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How do I instantiate a Queue object in java?
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java.util.Queue is an interface. You can't instantiate interfaces. You need to create an instance of a class implementing that interface. In this case a LinkedList is such a class.
– Mihai Toader
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