1packagecn.itcast.demo01.demo01.demo05;2importjava.util.ArrayList;3importjava.util.Random;4importjava.util.Scanner;5publicclassDemo05person {6publicstaticvoidmain(String[] args) {7// 创建一个ArrayList集合,集合名字是list8ArrayList<String> list =newArrayList<>();9// 打印ArrayList集合的名字list,...
利用这个方法,可以先打乱List中元素的顺序,然后取出第一个元素作为随机取出的元素。 importjava.util.Collections;importjava.util.List;publicclassRandomListElement{publicstatic<T>TgetRandomElement(List<T>list){Collections.shuffle(list);returnlist.get(0);}publicstaticvoidmain(String[]args){List<String>fruits...
importjava.util.ArrayList;importjava.util.List;importjava.util.Random;publicclassLotteryWithWeights{staticclassCandidate{ String name;intweight;// 权重publicCandidate(String name,intweight){this.name = name;this.weight = weight; } }publicstaticvoidmain(String[] args){ List<Candidate> candidates =new...
下面是使用 Java Stream 实现随机取一条数据的代码示例: importjava.util.List;importjava.util.Random;importjava.util.stream.Collectors;importjava.util.stream.Stream;publicclassRandomStreamDemo{publicstaticvoidmain(String[]args){List<String>data=List.of("apple","banana","orange","grape","watermelon")...
{ArrayList<String>list=newArrayList<>();//类型推断,用左边推断右边int[]arr={1,2,3,4};//类型推断,用左边推断右边}//语法格式四:Lambda 若只需要一个参数时,参数的小括号可以省略@Testpublicvoidtest4(){//未使用Lambda表达式Consumer<String>con=newConsumer<String>(){@Overridepublicvoidaccept(String s...
{ Random rand = new Random(); List<String> givenList = Arrays.asList("one", "two", "three", "four"); int numberOfElements = 2; for (int i = 0; i < numberOfElements; i++) { int randomIndex = rand.nextInt(givenList.size()); String randomElement = givenList.get(randomIndex...
原来是 String 重写了 Object 的 equals 方法,把引用比较改成了值比较。 「总结」:== 对于基本类型来说是值比较,对于引用类型来说是比较的是引用;而 equals 默认情况下是引用比较,只是很多类重新了 equals 方法,比如 String、Integer 等把它变成了值比较,所以一般情况下 equals 比较的是值是否相等。
It has JDK-compatible List, Set and Map implementations with a rich API, additional types not found in the JDK like Bags, Multimaps and set of utility classes that work with any JDK compatible Collections, Arrays, Maps or Strings. The iteration protocol was inspired by the Smalltalk collection...
import java.util.ArrayList; import java.util.LinkedList; import java.util.List; import java.util.RandomAccess; public class RandomAccessDemo { public static void main(String[] args) { List<String> list1 = new ArrayList<>(); list1.add("Apple"); list1.add("Banana"); list1.add("Orange...
random-string Generate random strings based on a pattern. Synopsis RandomStringGeneratorgenerator=newRandomStringGenerator();// generates random string (e.g. "aB4@X.Ç")StringrandomString=generator.generateFromPattern("cCn!.sb"); RandomStringGeneratorgenerator=newRandomStringGenerator();// generates...