EN
Java - 4 different ways to generate random float in range
4 points
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public static float nextFloatBetween(float min, float max) {2
return (ThreadLocalRandom.current().nextFloat() * (max - min)) + min;3
}Example:
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System.out.println(nextFloatBetween(4.0f, 8.0f)); // 4.28421642
System.out.println(nextFloatBetween(100.0f, 900.0f)); // 457.321083
System.out.println(nextFloatBetween(-6.5f, -3.5f)); // -4.848301xxxxxxxxxx1
public static float nextFloatBetween2(float min, float max) {2
return (new Random().nextFloat() * (max - min)) + min;3
}Example:
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System.out.println(nextFloatBetween2(4.0f, 8.0f)); // 6.4549872
System.out.println(nextFloatBetween2(100.0f, 900.0f)); // 518.712043
System.out.println(nextFloatBetween2(-6.5f, -3.5f)); // -3.6078863xxxxxxxxxx1
public static float nextFloatBetween3(float min, float max) {2
// java 8 + DoubleStream + cast to float3
return (float) new Random().doubles(min, max).limit(1).findFirst().getAsDouble();4
}Example:
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System.out.println(nextFloatBetween3(4.0f, 8.0f)); // 4.0267762
System.out.println(nextFloatBetween3(100.0f, 900.0f)); // 542.03563
System.out.println(nextFloatBetween3(-6.5f, -3.5f)); // -5.739404xxxxxxxxxx1
public static float nextFloatBetween4(float min, float max) {2
return (float) (Math.random() * (max - min)) + min;3
}Example:
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System.out.println(nextFloatBetween4(4.0f, 8.0f)); // 6.4549872
System.out.println(nextFloatBetween4(100.0f, 900.0f)); // 518.712043
System.out.println(nextFloatBetween4(-6.5f, -3.5f)); // -3.6078863Generate 2000 float numbers in range 2.0f and 4.0fSort them in asc order.
Print all 2000 floats in sorted order and verify that all of the numbers at the beginning are around 2.0f and at the end around of 4.0f.
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public static void testFloatInRange() {2
List<Float> list = new ArrayList<>();3
for (int i = 0; i < 2000; i++) {4
//float rand = nextFloatBetween(2.0f, 4.0f);5
//float rand = nextFloatBetween2(2.0f, 4.0f);6
//float rand = nextFloatBetween3(2.0f, 4.0f);7
float rand = nextFloatBetween4(2.0f, 4.0f);8
list.add(rand);9
}10
list.sort(Float::compareTo);11
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// print 2000 sorted floats in asc order13
list.forEach(System.out::println);14
}15
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public static void main(String[] args) {17
testFloatInRange();18
}Output (only first 5 x floats and last 5 x floats):
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2.00019962
2.00111343
2.00217774
2.0068525
2.00914346
...7
3.99701218
3.99754529
3.997820910
3.998258611
3.9999447ThreadLocalRandom - Java docs
Math - Java docs
Random - Java docs
DoubleStream - Java docs