java.util.Random#nextInt ( )源码实例Demo

public void assign(DelegateTask task) throws Exception {
	if (null == userId) {
		LOG.warn("处理人选择器(资源中随机分配)用户编号表达式为空 ! 节点编号：" + task.getNodeId());
		return;
	}
	// 获取待分配的用户
	List<String> userIds = AssigneeUtil.executionExpressionObj(userId);
	if (userIds.size() == 1) {
		task.setAssignee(StringUtil.trim(userIds.get(0)));
	} else {
		// 随机产生
		Random random = new Random();
		int index = random.nextInt(userIds.size());
		task.setAssignee(StringUtil.trim(userIds.get(index)));
	}
	
}
 

@Override
public void update(TimeStep timeStep, ParticleData particles) {
    this.spawnTimer.update(timeStep);
    if(this.spawnTimer.isOnFirstTime()) {
        particles.emitter.resetUpdaters();
        
        Random rand = particles.emitter.getRandom();
        if(this.maxSpawnTime > this.minSpawnTime) {
            long timer = this.minSpawnTime + rand.nextInt((int)(this.maxSpawnTime - this.minSpawnTime));                
            this.spawnTimer.setEndTime(timer);
            this.spawnTimer.reset();
            
            particles.reset();                
        }
        
        for(int i = 0; i < this.batchSize; i++) {
            int index = particles.spawnParticle();
            if(index > -1) {                    
                updateSingleParticles(index, timeStep, particles);
            }
        }
    }
}
 

@Override
public String getPreAdj(Random rand) {
	String str = "";
	switch(rand.nextInt(2)) {
		case 0:
			str = "Healing";
			break;
		case 1:
			str = "Rejuvenating";
			break;
		case 2:
			str = "Holy";
			break;
	}
	return str;
}
 

/**
 * Task to get the target node for vm crash
 */
protected ClientVmInfo getTargetNodeToKill(Region region) {
  if (region instanceof PartitionedRegion) {
    List otherVMs = new ArrayList(ClientVmMgr.getOtherClientVmids());
    if (ExecuteExceptionBB.getBB().getSharedMap().get(CACHE_CLOSED_VM) != null) {
      Integer cacheClosedVmId = (Integer)ExecuteExceptionBB.getBB()
          .getSharedMap().get(CACHE_CLOSED_VM);
      otherVMs.remove(cacheClosedVmId);
    }
    return new ClientVmInfo((Integer)otherVMs.get(0));
  }
  else {
    List endpoints = BridgeHelper.getEndpoints();
    Random rand = new Random();
    int index = rand.nextInt(endpoints.size() - 1);
    BridgeHelper.Endpoint endpoint = (BridgeHelper.Endpoint)endpoints
        .get(index);
    ClientVmInfo target = new ClientVmInfo(endpoint);
    return target;
  }
}
 

@Test
void removeAllWithIteratorTest() {
    final Random rng = new Random(RAND_SEED);
    final LongHopscotchSet hopscotchSet = new LongHopscotchSet(HHASH_NVALS);
    for (int valNo = 0; valNo != HHASH_NVALS; ++valNo) {
        final long longVal = ((long) rng.nextInt()) & ~Long.MIN_VALUE;
        hopscotchSet.add(longVal);
    }
    final LongIterator itr = hopscotchSet.iterator();
    while (itr.hasNext()) {
        final long next = itr.next();
        itr.remove();
        Assert.assertFalse(hopscotchSet.contains(next));
    }
    Assert.assertEquals(hopscotchSet.size(), 0);
}
 

@Test
public void testString()
    throws IOException {
  // use arbitrary cardinality and avg string length
  // we will test with complete randomness
  int initialCapacity = 5;
  int estimatedAvgStringLength = 30;
  try (VarByteSingleColumnSingleValueReaderWriter readerWriter =
      new VarByteSingleColumnSingleValueReaderWriter(_memoryManager, "StringColumn",  initialCapacity, estimatedAvgStringLength)) {
    int rows = 1000;
    Random random = new Random();
    String[] data = new String[rows];

    for (int i = 0; i < rows; i++) {
      // generate a random string of length between 10 and 100
      int length = 10 + random.nextInt(100 - 10);
      data[i] = RandomStringUtils.randomAlphanumeric(length);
      readerWriter.setString(i, data[i]);
    }

    for (int i = 0; i < rows; i++) {
      Assert.assertEquals(readerWriter.getString(i), data[i]);
    }
  }
}
 

/**
 * permutes the elements of a given array.
 *
 * @param v       the array to permute
 * @param random  the random number generator.
 */
protected void permute( int v[], Random random ) {

  for(int i = v.length - 1; i > 0; i-- ) {
    int j = random.nextInt( i + 1 );
    if( i != j ) {
      int tmp = v[i];
      v[i] = v[j];
      v[j] = tmp;
    }
  }
}
 

/**
 * Generates a string with given length containing random upper case characters ([A-Z]).
 * @param len length of the generated string
 * @return random upper case characters ([A-Z])
 */
public static String generateData(final int len) {
  Random random = new Random();
  StringBuilder b = new StringBuilder(len);
  for (int j = 0; j < len; j++) {
    final char c = (char) ('A' + random.nextInt('Z' - 'A' + 1));
    b.append(c);
  }
  return b.toString();
}
 

@SuppressWarnings("SameParameterValue")
public static String csRandomAlphaNumericString(int numChars) {
	SecureRandom secRand = new SecureRandom();
	Random rand = new Random();
	char[] buff = new char[numChars];

	for (int i = 0; i < numChars; ++i) {
		// reseed rand once you've used up all available entropy bits
		if ((i % 10) == 0)
			rand.setSeed(secRand.nextLong()); // 64 bits of random!

		buff[i] = VALID_CHARACTERS[rand.nextInt(VALID_CHARACTERS.length)];
	}
	return new String(buff);
}
 

/**
 * Returns a string filled with (deterministic) random characters to get a string that won't
 * compress to a tiny size.
 */
private String generateLongRandomString() {
  StringBuilder sb = new StringBuilder();
  Random random = new Random(0);
  for (int i = 0; i < 16 * 1024; ++i) {
    char c = (char) random.nextInt(128);
    sb.append(c);
  }
  return sb.toString();
}
 

public static String[] getRandomShortName(String name)
{
    String[] fileAndExtension = new String[2];
    String strStep1 = name.replaceAll("\\s+", "");
    boolean first = false;
    StringBuilder strStep2Builder = new StringBuilder(strStep1);
    for(int i=strStep1.length()-1;i>=0;i--)
    {
        if(strStep1.charAt(i) == '.' && !first)
        {
            first = true;
        }else if(strStep1.charAt(i) == '.' && first)
        {
            strStep2Builder.deleteCharAt(i);
        }
    }

    String[] strStep3 = strStep2Builder.toString().split("\\.");
    if(strStep3.length > 1)
    {
        if(strStep3[1].length() > 3)
            strStep3[1] = strStep3[1].substring(0, 3);
        fileAndExtension[1] = strStep3[1];
    }else
        fileAndExtension[1] = "";

    String shortName = "";
    Random r = new Random();
    for(int i=0; i<=5;i++)
    {
        char c = (char)(r.nextInt(26) + 'a');
        shortName += String.valueOf(c);
    }

    shortName += "~";
    shortName += String.valueOf((int) (Math.random() * 10));
    fileAndExtension[0] = shortName;
    return fileAndExtension;
}
 

private static String randomString(Random rnd, int minLength, int maxLength, int percentNonAscii) {

    final StringBuilder sb = new StringBuilder(maxLength - minLength + 1);
    int remaining = minLength + rnd.nextInt(maxLength - minLength + 1);
    while (remaining > 0) {
      if (percentNonAscii == 0 || rnd.nextInt(100) > percentNonAscii) {
        sb.appendCodePoint((rnd.nextInt(0x7F) + 1));
      } else {
        sb.appendCodePoint(rnd.nextInt(Character.MAX_CODE_POINT) + 1);
      }
      remaining--;
    }

    return sb.toString();
  }
 

private static int nextDate(Random random)
{
    return MIN_GENERATED_DATE + random.nextInt(MAX_GENERATED_DATE - MIN_GENERATED_DATE);
}
 

@Test
public void testRandomPolynomialsFirstDerivative() {

    Random random = new Random(0x570803c982ca5d3bl);

    for (int i = 0; i < 100; ++i) {

        int maxDegree = 0;
        PolynomialFunction[] p      = new PolynomialFunction[5];
        PolynomialFunction[] pPrime = new PolynomialFunction[5];
        for (int k = 0; k < p.length; ++k) {
            int degree = random.nextInt(7);
            p[k]      = randomPolynomial(degree, random);
            pPrime[k] = p[k].polynomialDerivative();
            maxDegree = FastMath.max(maxDegree, degree);
        }

        HermiteInterpolator interpolator = new HermiteInterpolator();
        for (int j = 0; j < 1 + maxDegree / 2; ++j) {
            double x = 0.1 * j;
            double[] values      = new double[p.length];
            double[] derivatives = new double[p.length];
            for (int k = 0; k < p.length; ++k) {
                values[k]      = p[k].value(x);
                derivatives[k] = pPrime[k].value(x);
            }
            interpolator.addSamplePoint(x, values, derivatives);
        }

        for (double x = 0; x < 2; x += 0.1) {
            DerivativeStructure[] y = interpolator.value(new DerivativeStructure(1, 1, 0, x));
            Assert.assertEquals(p.length, y.length);
            for (int k = 0; k < p.length; ++k) {
                Assert.assertEquals(p[k].value(x), y[k].getValue(), 1.0e-8 * FastMath.abs(p[k].value(x)));
                Assert.assertEquals(pPrime[k].value(x), y[k].getPartialDerivative(1), 4.0e-8 * FastMath.abs(p[k].value(x)));
            }
        }

        PolynomialFunction[] result = interpolator.getPolynomials();
        for (int k = 0; k < p.length; ++k) {
            checkPolynomial(p[k], result[k]);
        }

    }
}
 

@Test
public void testSplitableCodecs() throws Exception {
  final Job job = Job.getInstance(defaultConf);
  final Configuration conf = job.getConfiguration();

  // Create the codec
  CompressionCodec codec = null;
  try {
    codec = (CompressionCodec)
    ReflectionUtils.newInstance(conf.getClassByName("org.apache.hadoop.io.compress.BZip2Codec"), conf);
  } catch (ClassNotFoundException cnfe) {
    throw new IOException("Illegal codec!");
  }
  Path file = new Path(workDir, "test"+codec.getDefaultExtension());

  int seed = new Random().nextInt();
  LOG.info("seed = " + seed);
  Random random = new Random(seed);

  localFs.delete(workDir, true);
  FileInputFormat.setInputPaths(job, workDir);

  final int MAX_LENGTH = 500000;
  FileInputFormat.setMaxInputSplitSize(job, MAX_LENGTH / 20);
  // for a variety of lengths
  for (int length = 0; length < MAX_LENGTH;
       length += random.nextInt(MAX_LENGTH / 4) + 1) {

    LOG.info("creating; entries = " + length);

    // create a file with length entries
    Writer writer =
      new OutputStreamWriter(codec.createOutputStream(localFs.create(file)));
    try {
      for (int i = 0; i < length; i++) {
        writer.write(Integer.toString(i * 2));
        writer.write("\t");
        writer.write(Integer.toString(i));
        writer.write("\n");
      }
    } finally {
      writer.close();
    }

    // try splitting the file in a variety of sizes
    KeyValueTextInputFormat format = new KeyValueTextInputFormat();
    assertTrue("KVTIF claims not splittable", format.isSplitable(job, file));
    for (int i = 0; i < 3; i++) {
      int numSplits = random.nextInt(MAX_LENGTH / 2000) + 1;
      LOG.info("splitting: requesting = " + numSplits);
      List<InputSplit> splits = format.getSplits(job);
      LOG.info("splitting: got =        " + splits.size());

      // check each split
      BitSet bits = new BitSet(length);
      for (int j = 0; j < splits.size(); j++) {
        LOG.debug("split["+j+"]= " + splits.get(j));
        TaskAttemptContext context = MapReduceTestUtil.
          createDummyMapTaskAttemptContext(job.getConfiguration());
        RecordReader<Text, Text> reader = format.createRecordReader(
          splits.get(j), context);
        Class<?> clazz = reader.getClass();
        MapContext<Text, Text, Text, Text> mcontext =
          new MapContextImpl<Text, Text, Text, Text>(job.getConfiguration(),
          context.getTaskAttemptID(), reader, null, null,
          MapReduceTestUtil.createDummyReporter(), splits.get(j));
        reader.initialize(splits.get(j), mcontext);

        Text key = null;
        Text value = null;
        try {
          int count = 0;
          while (reader.nextKeyValue()) {
            key = reader.getCurrentKey();
            value = reader.getCurrentValue();
            final int k = Integer.parseInt(key.toString());
            final int v = Integer.parseInt(value.toString());
            assertEquals("Bad key", 0, k % 2);
            assertEquals("Mismatched key/value", k / 2, v);
            LOG.debug("read " + k + "," + v);
            assertFalse(k + "," + v + " in multiple partitions.",bits.get(v));
            bits.set(v);
            count++;
          }
          if (count > 0) {
            LOG.info("splits["+j+"]="+splits.get(j)+" count=" + count);
          } else {
            LOG.debug("splits["+j+"]="+splits.get(j)+" count=" + count);
          }
        } finally {
          reader.close();
        }
      }
      assertEquals("Some keys in no partition.", length, bits.cardinality());
    }

  }
}
 

void build(int[] a, int m, Random random) {
    for (int i = 0; i < a.length; i++) {
        a[i] = random.nextInt(m);
    }
}
 

@Override
public CharType getRandom(Random rnd) {
	return new CharType((char) rnd.nextInt(10000));
}
 

public static void checkBlockHeaderCheckPoint(EleConn conn)
  throws Exception
{
  
  //int blk_n = 109;
  //int cp = 32911;
  Random rnd = new Random();

  for(int i=0; i<20; i++)
  {
    JSONArray params = new JSONArray();
    int cp = rnd.nextInt(630000)+10;
    int blk_n = rnd.nextInt(cp);
    //cp = 5;
    //blk_n = 2;

    params.add(blk_n);
    params.add(cp);

    JSONObject msg = conn.request("blockchain.block.header", params);
    JSONObject result = (JSONObject) msg.get("result");

    String header = (String) result.get("header");
    
    if (header.length() != 160) throw new Exception("Header not 160 chars"); 
    JSONArray branch = (JSONArray) result.get("branch");

    String header_hex = (String) result.get("header");

    
    String root = (String) result.get("root");
    validateMerkle(HexUtil.hexStringToBytes(header_hex), branch, blk_n, cp, root);

  }
  

  
}
 

/**
  * Generates a basic dense vector in Polar form
  *
  * @return Dense representation of vector in Polar form.
  */

 public ComplexVector generateRandomVector(int dimension, Random random) {
   
if (getDominantMode().equals(Mode.HERMITIAN))
	return generateHermitianRandomVector(dimension, random);


ComplexVector randomVector = new ComplexVector(dimension, Mode.POLAR_DENSE);

   for (int d = 0; d < randomVector.phaseAngles.length; d++)
     randomVector.phaseAngles[d] = (short) random.nextInt(CircleLookupTable.PHASE_RESOLUTION);

   return randomVector;
 }
 

/**
 * 获取伪随机 int 值
 * @param random Random
 * @return 随机 int 值
 */
public static int nextInt(final Random random) {
    return random != null ? random.nextInt() : new Random().nextInt();
}