day18/MathDemo1.java

本文详细介绍了Java中几种生成随机数的方法,包括Math类的random()方法、Random类的nextInt(int n)方法以及Collections工具类的shuffle方法。通过具体实例展示了如何使用这些方法来生成不同范围内的随机数。
/*
Math工具类中的 随机数方法:
Math.random();

java.lang包		Math工具类(静态方法)			Math.random()

java.uitl包		Random类(非静态方法)			对象.nextInt(int n)//返回一个伪随机数,它是取自此随机数生成器序列的、在 0(包括)和指定值(不包括)之间均匀分布的 int 值。

java.util包		Collections工具类(静态方法)		Collections.shuffle(List<?> list)

*/
class MathDemo1 
{
	public static void sop(Object obj)
	{
		System.out.println(obj);
	}
	public static void main(String[] args) 
	{
		for(int x=0;x<10;x++)
		{
			double d = Math.random();//返回带正号的 double 值,该值大于等于 0.0 且小于 1.0。(包含0不包含1)
			sop(d);
		}

		for(int x=0;x<10;x++)
		{
			int d = (int)(Math.random()*6+1);//强行取整,1-6之间,随机骰子
			sop(d);
		}
	}	
}

发生了这样的错误org.junit.platform.commons.PreconditionViolationException: Classpath resource [/com/main/nextDay.csv] does not exist at java.base/java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:215) at java.base/java.util.ArrayList$ArrayListSpliterator.forEachRemaining(ArrayList.java:1709) at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:570) at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:560) at java.base/java.util.stream.ForEachOps$ForEachOp.evaluateSequential(ForEachOps.java:151) at java.base/java.util.stream.ForEachOps$ForEachOp$OfRef.evaluateSequential(ForEachOps.java:174) at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:265) at java.base/java.util.stream.ReferencePipeline.forEach(ReferencePipeline.java:636) at java.base/java.util.stream.ReferencePipeline$7$1FlatMap.accept(ReferencePipeline.java:294) at java.base/java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:215) at java.base/java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:215) at java.base/java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:215) at java.base/java.util.ArrayList$ArrayListSpliterator.forEachRemaining(ArrayList.java:1709) at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:570) at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:560) at java.base/java.util.stream.ForEachOps$ForEachOp.evaluateSequential(ForEachOps.java:151) at java.base/java.util.stream.ForEachOps$ForEachOp$OfRef.evaluateSequential(ForEachOps.java:174) at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:265) at java.base/java.util.stream.ReferencePipeline.forEach(ReferencePipeline.java:636) at java.base/java.util.stream.ReferencePipeline$7$1FlatMap.accept(ReferencePipeline.java:294) at java.base/java.util.ArrayList$ArrayListSpliterator.forEachRemaining(ArrayList.java:1709) at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:570) at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:560) at java.base/java.util.stream.ForEachOps$ForEachOp.evaluateSequential(ForEachOps.java:151) at java.base/java.util.stream.ForEachOps$ForEachOp$OfRef.evaluateSequential(ForEachOps.java:174) at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:265) at java.base/java.util.stream.ReferencePipeline.forEach(ReferencePipeline.java:636) at java.base/java.util.ArrayList.forEach(ArrayList.java:1597) at java.base/java.util.ArrayList.forEach(ArrayList.java:1597) Suppressed: org.junit.platform.commons.PreconditionViolationException: Configuration error: You must configure at least one set of arguments for this @ParameterizedTest at java.base/java.util.stream.AbstractPipeline.close(AbstractPipeline.java:355) at java.base/java.util.stream.ReferencePipeline$7$1FlatMap.accept(ReferencePipeline.java:289) ... 9 more
03-24
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