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    <p>Right now, you're seeding the RNG and pulling the entire sequence every time you want a number. You don't need to do that. Instead, give <code>rand</code> a wider scope. That way you can reuse it each time you want to get a number.</p> <p>This makes things simpler because you don't need to iterate over the list each time, so you don't have to build the list <em>at all</em>. That means you no longer have to loop in <code>pickNumber()</code>, and most of what you have in <code>selectObject()</code> is obsolete also. </p> <p>Not only is this <em>simpler</em>, but it's also <em>faster</em>. Instead of looping/generating the whole list each time, you only have to grab a couple numbers until you have a good one. On average, this will be <code>4/3</code> tries per call, since about a third will be duplicates.</p> <p>Try something like this instead:</p> <pre><code>public class UniqueRandomObjectSelector { int seed = 11231; int prev = -1; int range = 3; Random rand; int[] values; int maxIndex = 1000; public static void main(String[] args) { /// to generate value 37 on the fly System.out.println("37th value is " + selectObject(37)); /// to print 1000 in order (and store them in an array) rand = new Random(seed); list = new int[maxIndex+1]; for (int i = 0; i &lt;= maxIndex; i++) { values[i] = getRandomNonRepeating(); System.out.println(i + "th random value is " + values[i]); } /// to get value 37 from values[] System.out.println("37th value is " + values[37]); } static int selectObject(int index){ rand = new Random(seed); int value = -1; for(int i=0; i&lt;=index; i++) value = getRandomNonRepeating(); return value; } static int getRandomNonRepeating() { int next = -1; while(next == prev || next &lt; 0){ next = rand.nextInt(range); } prev = next; return next; } } </code></pre>
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    1. POSequence of random selection with no two consecutive objects same
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    1. USGeobits
    1. USGeobits
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    1. COThis is indeed clean however the only reason I have to re-generate the whole sequence everytime because I need a master function which just takes the sequence number and gives me the random number associated with it. My Ultimate goal is to call selectObject(int index) as part of webservice which takes the index as query parameter. My program will not have a main function like above to generate all the numbers at same go.
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      1. USSoulMan
    2. COAh, I see. Well, you can still do that more efficiently. Basically your `selectObject(index)` will just loop exactly like the `main()` does above, but return the last one instead of printing them all. Let me update the code sample.
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    3. COAlternatively, if you know `index` will not go above a certain value, you could just precompute them(up to max) into an array and persistently store it. Then it's as simple as retrieving one number each time.
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