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java random examples

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This commit is contained in:
eugenp 2014-07-21 22:08:24 +03:00
parent 706ec1d67d
commit 04f7919eb3
1 changed files with 50 additions and 6 deletions
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56
core-java/src/test/java/org/baeldung/java/CoreJavaRandomUnitTest.java
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@ -2,6 +2,7 @@ package org.baeldung.java;
import java.util.Random; import java.util.Random;
import org.apache.commons.lang3.RandomStringUtils;
import org.apache.commons.math3.random.RandomDataGenerator; import org.apache.commons.math3.random.RandomDataGenerator;
import org.junit.Test; import org.junit.Test;
@ -99,17 +100,17 @@ public class CoreJavaRandomUnitTest {
} }
@Test @Test
public void givenUsingPlainJava_whenGeneratingRandomDoubleBounded_thenCorrect() { public void givenUsingApache_whenGeneratingRandomDoubleUnbounded_thenCorrect() {
final double leftLimit = 1D; final double generatedDouble = new RandomDataGenerator().getRandomGenerator().nextDouble();
final double rightLimit = 10D;
final double generatedDouble = leftLimit + new Random().nextDouble() * (rightLimit - leftLimit);
System.out.println(generatedDouble); System.out.println(generatedDouble);
} }
@Test @Test
public void givenUsingApache_whenGeneratingRandomDoubleUnbounded_thenCorrect() { public void givenUsingPlainJava_whenGeneratingRandomDoubleBounded_thenCorrect() {
final double generatedDouble = new RandomDataGenerator().getRandomGenerator().nextDouble(); final double leftLimit = 1D;
final double rightLimit = 10D;
final double generatedDouble = leftLimit + new Random().nextDouble() * (rightLimit - leftLimit);
System.out.println(generatedDouble); System.out.println(generatedDouble);
} }
@ -123,4 +124,47 @@ public class CoreJavaRandomUnitTest {
System.out.println(generatedDouble); System.out.println(generatedDouble);
} }
// tests - random String
@Test
public void givenUsingPlainJava_whenGeneratingRandomStringUnbounded_thenCorrect() {
final byte[] array = new byte[7]; // length is bounded by 7
new Random().nextBytes(array);
final String generatedString = new String(array);
System.out.println(generatedString);
}
@Test
public void givenUsingPlainJava_whenGeneratingRandomStringBounded_thenCorrect() {
final int leftLimit = 97; // letter 'a'
final int rightLimit = 122; // letter 'z'
final int targetStringLength = 10;
final StringBuilder buffer = new StringBuilder(targetStringLength);
for (int i = 0; i < targetStringLength; i++) {
final int randomLimitedInt = leftLimit + (int) (new Random().nextFloat() * (rightLimit - leftLimit));
buffer.append((char) randomLimitedInt);
}
final String generatedString = new String(buffer);
System.out.println(generatedString);
}
@Test
public void givenUsingApache_whenGeneratingRandomStringUnbounded_thenCorrect() {
final String generatedString = RandomStringUtils.random(10);
System.out.println(generatedString);
}
@Test
public void givenUsingApache_whenGeneratingRandomStringBounded_thenCorrect() {
final int length = 10;
final boolean useLetters = true;
final boolean useNumbers = false;
final String generatedString = RandomStringUtils.random(length, useLetters, useNumbers);
System.out.println(generatedString);
}
} }