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W3spoint99
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Asked: 2025-01-24T14:42:33+00:00 In:

How to generate random integers within a specific range in Java?

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How to generate random integers within a specific range in Java?

How to generate a random int value in a specific range?

The following methods have bugs related to integer overflow:

randomNum = minimum + (int)(Math.random() * maximum);
// Bug: `randomNum` can be bigger than `maximum`.

Random rn = new Random();
int n = maximum - minimum + 1;
int i = rn.nextInt() % n;
randomNum =  minimum + i;
// Bug: `randomNum` can be smaller than `minimum`.
integersJavarandom
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1 Answer

  1. Saralyn
    Teacher

    There are several differences between HashMap and Hashtable in Java:

    1. Hashtable is synchronized, whereas HashMap is not. This makes HashMap better for non-threaded applications, as unsynchronized Objects typically perform better than synchronized ones.
    2. Hashtable does not allow null keys or values. HashMap allows one null key and any number of null values.
    3. One of HashMap’s subclasses is LinkedHashMap, so in the event that you’d want predictable iteration order (which is insertion order by default), you could easily swap out the HashMap for a LinkedHashMap. This wouldn’t be as easy if you were using Hashtable.

    Since synchronization is not an issue for you, I’d recommend HashMap. If synchronization becomes an issue, you may also look at ConcurrentHashMap.

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