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Java 8 NullPointerException in Collectors.toMap
The Java 8 Collectors.toMap throws a NullPointerException if one of the values is 'null'. I don't understand this behaviour, maps can contain null pointers as value without any problems. Is there a good reason why values cannot be null for Collectors.toMap ?
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Algorithm to implement a word cloud like Wordle
...some N. Assign each word a font size proportional to its count. Generate a Java2D Shape for each word, using the Java2D API.
Each word "wants" to be somewhere, such as "at some random x position in the vertical center". In decreasing order of frequency, do this for each word:
place the word where ...
Difference in System. exit(0) , System.exit(-1), System.exit(1 ) in Java
I'd like to know the difference between the following in Java
11 Answers
11
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Naming conventions for java methods that return boolean(No question mark)
...sing question mark at the end of method/function names in other languages. Java doesn't let me do this. As a workaround how else can I name boolean returning methods in Java? Using an is , has , should , can in the front of a method sound okay for some cases. Is there a better way to name such ...
Why are you not able to declare a class as static in Java?
Why are you not able to declare a class as static in Java?
14 Answers
14
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How do I cast a variable in Scala?
... you get the result of this pattern matching cast into a variable? like in java if it was String a = (String) b; what would the scala equivalent be?
– James McMahon
Jul 19 '12 at 3:58
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Copying a HashMap in Java
...ashmap
Program for copy all elements from one hashmap to another
import java.util.HashMap;
public class CloneHashMap {
public static void main(String a[]) {
HashMap hashMap = new HashMap();
HashMap hashMap1 = new HashMap();
hashMap.put(1, "One");
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Is it safe to get values from a java.util.HashMap from multiple threads (no modification)?
... accessed (via get(key) only) from multiple threads. Is it safe to use a java.util.HashMap in this way?
12 Answers
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Importing two classes with same name. How to handle?
...n omit the import statements and refer to them using the entire path. Eg:
java.util.Date javaDate = new java.util.Date()
my.own.Date myDate = new my.own.Date();
But I would say that using two classes with the same name and a similiar function is usually not the best idea unless you can make it re...
What does a just-in-time (JIT) compiler do?
...guage but yes, purely interpreted code (without any JITting) is slow. Even Java bytecode without a JITter is really slow.
– Mark Cidade
Sep 18 '08 at 22:07
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