1. Create a list collection and Random object. Write a while loop to put the randomly generated random number in the set (before putting it in, you need to judge whether the generated random number exists in the set, if it exists, give up, if it does not exist, put it in the set)
import java.util.ArrayList; import java.util.Arrays; import java.util.List; import java.util.Random; public class Test { public static void main(String[] args) { //调用函数，此次需求为：生成范围为[0,100)的10个随机数 System.out.println(getRandomNumList(10,0,100)); } //定义生成随机数并且装入集合容器的方法 //方法的形参列表分别为：生成随机数的个数、生成随机数的值的范围最小值为start(包含start)、值得范围值为end(不包含end) 可取值范围可表示为[start,end) public static List getRandomNumList(int nums,int start,int end){ //1.创建集合容器对象 List list = new ArrayList(); //2.创建Random对象 Random r = new Random(); //循环将得到的随机数进行判断，如果随机数不存在于集合中，则将随机数放入集合中，如果存在，则将随机数丢弃不做操作，进行下一次循环，直到集合长度等于nums while(list.size() != nums){ int num = r.nextInt(end-start) + start; if(!list.contains(num)){ list.add(num); } } return list; } }
2. Math.radom will randomly generate numbers greater than or equal to 0.0 and less than 1.0. Note that 1 still cannot be generated here.
package a; //不需要导入任何包 public class a { public static void main(String[] args) { int min=10,max=100; for(int i=0;i<10;i++) { int num=(int)(Math.random()*(max-min+1))+min; System.out.println(num); } //其余的不在一一列举 } }
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