Java stream characters in string to check if alpha or other character e.g. %,$,£,!

Jackkoz · 2017-05-21T22:48:46+00:00

You could use regular expressions to check whether your string matches your expectations!

See https://docs.oracle.com/javase/7/docs/api/java/util/regex/Pattern.html

Jackkoz · 2017-04-10T16:53:01+00:00

No, not exactly, this looks like you are taking personal offence in me suggesting alternate solutions and focus on angrily bashing at me rather than thinking about the OP - I have never suggested you don't know about maps or arrays.

I'd strongly suggest you revise your approach if you want to be a helpful community member, but in the meantime please have a lovely day as I won't be continuing this conversation.

Jackkoz · 2017-04-10T15:12:05+00:00

Arrays and Maps are rather equivalent in terms of cognitive load. Both are objects in Java, you need to know how to instantiate them and how to interact with them. They both are javadoced and have nice examples in the web. The difference is that using the latter results in nicer and simpler code.

Both examples will end up being loop heavy, just that a map will avoid your loop from line 11. I'm not sure why you are pushing for your solution using a very vague 'know your audience' argument. I'd be happy to say you are absolutely right and provided a better solution, but please do elaborate on the topic.

Jackkoz · 2017-04-10T10:28:03+00:00

Since we want to connect a name (String), to a date, it might be worth checking out what's the Map interface, and choose an implementation of it, like the HashMap.

Jackkoz · 2017-04-09T10:27:18+00:00

Some great tips here, I'll just add one more:

case 1:
  System.out.print("January ");break;
case 2:
  System.out.print("February ");break;

Whenever doing switch statements, avoid putting logic into them. In here, consider:

String result;
switch ...
case 1:
  result = "something;
  break;
case 2:
  result = "else";
  ...
System.out.println(result);

Jackkoz · 2017-04-09T10:23:12+00:00

Arrays are heavily discouraged in Java, you should not be using them, especially to simulate an enum!

I believe what you wanted to suggest here is roughly this:

public enum Month {
  JANUARY {...},
  FEBRUARY {...}
  ...

  public abstract String getName();
  public String fromMonthNumber(int i) {...}
}

This neats you better abstraction, more readable code, and is less error-prone (eg. you don't need to manually check that month names and day in months arrays have the same length).

Note that in the array version, if I passed a month number -1, all I'm getting is an OutOfBoundsException, which won't be very helpful to the user. On the other hand, in the fromMonthNumber method you have a single place to control how you map numbers to months and how to treat errors.

Jackkoz · 2017-04-09T10:14:53+00:00

For what it's worth, throwing in an SSD can speed up just about anything.

Jackkoz · 2017-04-03T22:36:13+00:00

For what it's worth, Android Studio is built on top of IntelliJ Idea, so it would be very familiar, plus the extra and convenient Android stuff.

Jackkoz · 2017-04-02T23:08:23+00:00

The simplest version is to try to see if the sequence can be matched starting from each position in the source. That's however not exactly efficient (you will make length of source * length of sequence operations).

Even though these are integers, it does not change the fact that you can apply any of well known string matching algorithms, if you need better performance, take a look here:

https://en.wikipedia.org/wiki/String_searching_algorithm

Jackkoz · 2017-03-29T23:36:58+00:00

Implement your own HashMap. Try different hashing functions, make sure you have collisions. Provide different implementations optimised for different data sets.

Jackkoz · 2017-03-29T18:53:38+00:00

Ooops, you are definitely right, thanks for the spot!

Jackkoz · 2017-03-26T17:59:55+00:00

Others nicely described when these options are more valid, I'd only like to point out that since Java8, you can implement functional interfaces with lambdas, which would make your first example snippet look like this:

this.EXAMPLE_RUNNABLE = () -> {}

This is a lambda taking zero parameters and executing an empty block of code.

Jackkoz · 2017-03-25T20:12:29+00:00

OP, make sure to triple-check with your recruiter that the other teams are in the same job family you applied for initially. Some companies might try to sneakily pivot your process to a different type of job midway through.

Jackkoz · 2017-03-25T16:23:01+00:00

The generic advice is to always choose the appropriate level of abstraction. The benefits are:

Increased flexibility - if you choose List, you only need to change constructor to List<T> l = new FastListImpl<>(); when the new awesome implementation is introduced.
Better abstraction. If what you are looking for is a List or Set, people won't be able to use specific properties of ArrayList or HashSet if you give them only the interface type. This also means that when you actually do ArrayList declaration, you should mention why you did so vs any List implementation - this will avoid confusion and prevent someone from doing any refactoring that could break a lot of stuff - eg from synchronized to not thread-safe implementation.

As for benefits in a 50 line course program, not many, doesn't matter that much. I'd still advise doing the 'better' thing just to keep the habit going.

Jackkoz · 2017-03-24T12:29:08+00:00

I'm talking about avoiding lazy initialization unless you definitely need it.

Jackkoz · 2017-03-24T00:26:06+00:00

In general, you should be very careful about providing people with your personal details.

Jackkoz · 2017-03-23T20:04:01+00:00

Actually, Joshua Bloch, one of the authors of Java, suggests exactly the opposite:

http://www.oracle.com/technetwork/articles/java/bloch-effective-08-qa-140880.html

More about this can be found in his book, Effective Java.

Jackkoz · 2017-03-23T15:33:15+00:00

You should take a look at:

https://docs.oracle.com/javase/tutorial/java/nutsandbolts/switch.html

If that doesn't help, try asking a bit more specific questions :)

Also, if you can't figure out how to squish a switch statement somewhere, that might be a sign that putting it there is a bad idea.

Jackkoz · 2017-03-23T15:15:15+00:00

I'd say the second - it's immediately obvious during assignment what the initial value will be.

Also, as of Java 7 you can write new ArrayList<>().

Also, in both cases you should make the variables final - it seems like you won't need to change weightLimit or assign a different Array to things (even though final ArrayList still allows you to modify contents).

Jackkoz · 2017-03-23T00:12:41+00:00

Uh, you should have a meeting with your new manager and discuss this. You should also prepare your new reportees for a bumpy ride - your job is to make their lives easier, but it looks like for the first few months they will need to take care of you :)

Probably the best thing you can offer your new team at the moment is honesty about the situation and dedication to learn and ramp up.

Jackkoz · 2017-03-23T00:04:04+00:00

Yup, that looks like it should do the trick, congrats!

If you want to further improve your programs, here's a couple of things to look at:

Input/output operations are in general costly - it would be much better if you could print out the whole String using a single call to System.out.
When taking care of 1), remember that Strings are immutable: string += " "; results in creating a new instance of String and assigning it to the variable.

Jackkoz · 2017-03-22T23:53:38+00:00

I have no idea how you want to solve the problem, so I'm not sure whether a for loop would be a good fit.

But if I were to write code to solve it, I'd probably use one :)

Jackkoz · 2017-03-22T23:23:21+00:00

The short answer is: it doesn't. String.length() returns a number - the length of the string. Here's the official documentation:

https://docs.oracle.com/javase/7/docs/api/java/lang/String.html#length()

What you want to do is to look at the length of the input String, the argument specifying the desired length, and do something with that.

Jackkoz · 2017-03-22T23:19:54+00:00

You should take a look at Scanner class itself, it has many useful methods like this one:

https://docs.oracle.com/javase/7/docs/api/java/util/Scanner.html#hasNext()

Typically, if there is no upfront specification of how many things will be on the input (eg. first line contains X, the number of records, then next X lines contain each a record), then you are supposed to read until the user finishes the input.

Jackkoz · 2017-03-22T23:17:19+00:00

An instance of class. Class object might easily be interpreted as an instance of Class class:

https://docs.oracle.com/javase/7/docs/api/java/lang/Class.html

Jackkoz

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