Frank Mi

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since Aug 19, 2020
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Recent posts by Frank Mi

Md Zuanyeed Kamal wrote:However, if we have regular expression on only one side "[a-z].*" , or ".*[a-z]" , then what would it mean in general ? or how would you explain that ?

"[a-z].*" : starts with a lower case letter (whatever after the first character doesn't matter)
".*[a-z]" : ends with a lower case letter (whatever before the last character doesn't matter)
".*[a-z].*" : contains a lower case letter (a string has a lower case letter in the middle, whatever before or after it doesn't matter)
14 hours ago
In regular expression, .* matches any string sequences (in a same line of course). When you have .* on both side, that means the string can start and end with anything before and after [a-z]. That is to say, if a string has [a-z] in it, no matter what other characters before and after it, the regular expression matches.

".*[a-z].*" matches if: the string CONTAINS (at least one) lower case letter.
".*[A-Z].*" matches if: the string CONTAINS (at least one) upper case letter.
".*[0-9].*" matches if: the string CONTAINS (at least one) number.
"[a-zA-Z0-9]*" matches: all characters in the string are letters and numbers.
1 day ago
I just recalled another one, how do you pronounce "ArrayDeque"? Most of the time, I heard "Array Deck", but sometimes I also heard "Array Dee Queue". Somebody would argue that "Array Deck" doesn't sound like a queue.
1 day ago
It's very interesting that, though I still don't know how to pronounce "varargs", I learned how to pronounce "Gloucester" here.  
3 days ago
Great answer! It's very clear, thank you, Stephan! I will try it later.
3 days ago
It makes sense. This format is good enough. Thank you.

3 days ago
Sorry, I didn't make my question clear. My question is actually why doesn't it take unlimited numbers of key-value pairs like varargs.
3 days ago
Why Map.of() method takes up to 10 value pairs as input parameter?
3 days ago
Why the keySet() method of HashMap returns a Set<K> rather than a HashSet<K>? And why the values() method returns a Collection<V> rather than a more concrete type?
3 days ago
Do you pronounce it as two separate words like "var  args"? Or do you pronounce it as a single word, say, something like "vəˈrɑːrgs"?
3 days ago

Stephan van Hulst wrote:Types that implement Constable can express their values as a ConstantDesc. In short, if a class implements Constable, you can store its values in the JVM's constant pool and you can compile symbolic references to these constants into the class file. I suppose the purpose of all of this is that it allows Java to use compiled constants of types other than primitives and strings.

Does it mean, in this way, I can define my own constant variable types? Say, I can use my own class type in switch case expression?
3 days ago
Welcome to the Ranch.  

The difference is because your last print statement uses the print() method instead of the println() method.

System.out.println("") prints a new line, while System.out.print("") prints nothing.
4 days ago
I found that, from Java 12, Integer and other number classes also implement the Constable and ConstantDesc interface. What are they used for? How do they affect our programming?
4 days ago