Examples of java.util.Random.nextDouble()

java.util.Random.nextDouble()
Returns the next pseudorandom, uniformly distributed {@code double} value between {@code 0.0} and{@code 1.0} from this random number generator's sequence.
The general contract of {@code nextDouble} is that one{@code double} value, chosen (approximately) uniformly from therange {@code 0.0d} (inclusive) to {@code 1.0d} (exclusive), ispseudorandomly generated and returned.
The method {@code nextDouble} is implemented by class {@code Random}as if by:
```
  {@code}public double nextDouble()  return (((long)next(26) << 27) + next(27)) / (double)(1L << 53); }}
```
The hedge "approximately" is used in the foregoing description only because the {@code next} method is only approximately an unbiasedsource of independently chosen bits. If it were a perfect source of randomly chosen bits, then the algorithm shown would choose {@code double} values from the stated range with perfect uniformity.
[In early versions of Java, the result was incorrectly calculated as:
```
  {@code return (((long)next(27) << 27) + next(27)) / (double)(1L << 54);}
```
This might seem to be equivalent, if not better, but in fact it introduced a large nonuniformity because of the bias in the rounding of floating-point numbers: it was three times as likely that the low-order bit of the significand would be 0 than that it would be 1! This nonuniformity probably doesn't matter much in practice, but we strive for perfection.] @return the next pseudorandom, uniformly distributed {@code double}value between {@code 0.0} and {@code 1.0} from thisrandom number generator's sequence @see Math#random

                Random rnd = new Random(9);
                int len = ARRAY_TEST_LENGTHS[i-1];
                data = new double[len];
                for (int ix = 0; ix < len; ++ix) {
                    // Need to scale: nextDouble is [0.0, 1.0[
                    double value = rnd.nextDouble();
                    if (rnd.nextBoolean()) {
                        value = (value * rnd.nextLong());
                    }
                    if (rnd.nextBoolean()) {
                        value = -value;

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        if (wiringProbability > 0) {
            for (int i = 0; i < numberOfNodes - 1 && !cancel; i++) {
                NodeDraft node1 = nodeArray[i];
                for (int j = i + 1; j < numberOfNodes && !cancel; j++) {
                    NodeDraft node2 = nodeArray[j];
                    if (random.nextDouble() < wiringProbability) {
                        EdgeDraft edgeDraft = container.factory().newEdgeDraft();
                        edgeDraft.setSource(node1);
                        edgeDraft.setTarget(node2);
                        container.addEdge(edgeDraft);
                    }

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          if (rand.nextBoolean()) {
            final byte[] value = Bytes.toBytes("value_for_row_" + iRow +
                "_cf_" + Bytes.toStringBinary(cf) + "_col_" + iCol + "_ts_" +
                ts + "_random_" + rand.nextLong());
            put.add(cf, qual, ts, value);
          } else if (rand.nextDouble() < 0.8) {
            del.deleteColumn(cf, qual, ts);
          } else {
            del.deleteColumns(cf, qual, ts);
          }
        }

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  private void testRandomTrieAndClassicRangeQuery(int precisionStep) throws Exception {
    final Random rnd=newRandom();
    String field="field"+precisionStep;
    int termCountT=0,termCountC=0;
    for (int i=0; i<50; i++) {
      int lower=(int)(rnd.nextDouble()*noDocs*distance)+startOffset;
      int upper=(int)(rnd.nextDouble()*noDocs*distance)+startOffset;
      if (lower>upper) {
        int a=lower; lower=upper; upper=a;
      }
      // test inclusive range

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    final Random rnd=newRandom();
    String field="field"+precisionStep;
    int termCountT=0,termCountC=0;
    for (int i=0; i<50; i++) {
      int lower=(int)(rnd.nextDouble()*noDocs*distance)+startOffset;
      int upper=(int)(rnd.nextDouble()*noDocs*distance)+startOffset;
      if (lower>upper) {
        int a=lower; lower=upper; upper=a;
      }
      // test inclusive range
      NumericRangeQuery<Integer> tq=NumericRangeQuery.newIntRange(field, precisionStep, lower, upper, true, true);

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  private void testRangeSplit(int precisionStep) throws Exception {
    final Random rnd=newRandom();
    String field="ascfield"+precisionStep;
    // 50 random tests
    for (int i=0; i<50; i++) {
      int lower=(int)(rnd.nextDouble()*noDocs - noDocs/2);
      int upper=(int)(rnd.nextDouble()*noDocs - noDocs/2);
      if (lower>upper) {
        int a=lower; lower=upper; upper=a;
      }
      // test inclusive range

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    final Random rnd=newRandom();
    String field="ascfield"+precisionStep;
    // 50 random tests
    for (int i=0; i<50; i++) {
      int lower=(int)(rnd.nextDouble()*noDocs - noDocs/2);
      int upper=(int)(rnd.nextDouble()*noDocs - noDocs/2);
      if (lower>upper) {
        int a=lower; lower=upper; upper=a;
      }
      // test inclusive range
      Query tq=NumericRangeQuery.newIntRange(field, precisionStep, lower, upper, true, true);

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    final Random rnd=newRandom();
    String field="field"+precisionStep;
    // 10 random tests, the index order is ascending,
    // so using a reverse sort field should retun descending documents
    for (int i=0; i<10; i++) {
      int lower=(int)(rnd.nextDouble()*noDocs*distance)+startOffset;
      int upper=(int)(rnd.nextDouble()*noDocs*distance)+startOffset;
      if (lower>upper) {
        int a=lower; lower=upper; upper=a;
      }
      Query tq=NumericRangeQuery.newIntRange(field, precisionStep, lower, upper, true, true);

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    String field="field"+precisionStep;
    // 10 random tests, the index order is ascending,
    // so using a reverse sort field should retun descending documents
    for (int i=0; i<10; i++) {
      int lower=(int)(rnd.nextDouble()*noDocs*distance)+startOffset;
      int upper=(int)(rnd.nextDouble()*noDocs*distance)+startOffset;
      if (lower>upper) {
        int a=lower; lower=upper; upper=a;
      }
      Query tq=NumericRangeQuery.newIntRange(field, precisionStep, lower, upper, true, true);
      TopDocs topDocs = searcher.search(tq, null, noDocs, new Sort(new SortField(field, SortField.INT, true)));

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        break;
      case 'F':
        result.add(r.nextFloat());
        break;
      case 'D':
        result.add(r.nextDouble());
        break;
      case 'S':
      case 'K':
        result.add(nextString(r, extractInt(cs)));
        break;

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