使用Java Collections.singletonList快速创建一个只包含一个元素的List Java中的 Collections 类是集合框架的一部分,该类提供了许多实用的方法来操作集合类对象。其中,单例列表(singletonList)是一个非常有用的方法,可以创建一个只包含一个元素的不可修改列表。这篇文章将介绍 singletonList
importjava.util.ArrayList;importjava.util.Collections;importjava.util.List;publicclassMain{publicstaticvoidmain(String[]args){List<String>list=newArrayList<>(Arrays.asList("one","two","three"));List<String>unmodifiableList=Collections.unmodifiableList(list);// 尝试修改不可变列表将抛出UnsupportedOperationE...
项目中有遇到过对Arrays.asList生成的ArrayList进行add操作时报出UnsupportedOperationException异常。这是因为此ArrayList并非彼ArrayList。 这里生成的ArrayList是Arrays的私有静态内部类。 与java.util.ArrayList非常类似,都继承自AbstractList。但是仅重写了toArray、get、set、in... ...
Allofthecollectionclassesdiscussedherecanbefoundinpackagejava.util TheCollectionLandscape Wildcards •ClassesandinterfacesinthecollectionframeworkcanhaveparametertypespecificationsthatdonotfullyspecifythetypepluggedinforthetypeparameterBecausetheyspecifyawiderangeofargumenttypes,theyareknownaswildcards publicvoid...
Java Collections JavaCollectionsFramework ApresentationbyEricFabricant Whatisit?“TheCollectionsFrameworkprovidesawell-designedsetofinterfacesandclassesforstoringandmanipulatinggroupsofdataasasingleunit,acollection.”-java.sun.com Sowhat?Well,TheframeworkprovidesaconvenientAPItomanyoftheabstractdatatypesfamiliartocomputer...
(require '[clojure.java.io :as io]) (defn- print-usage [] #1 (println "Usage: copy 'file-name' 'to-location' ['work-dir']")) (defn- copy #2 ([in out] (copy in out "./")) ([in out dir] (io/copy (io/file (str dir in)) (io/file out))) (defn -main [& args]...
importjava.util.ArrayList;importjava.util.Scanner;publicclassStudentManage {staticScanner sc =newScanner(System.in);//list表示存储学生信息的集合staticArrayList<Student> list =newArrayList<>();//set(int index, ele)publicstaticvoidmain(String[] args) {while(true){ ...
10 Creating an ArrayList object in the constructor In Java versions prior to version 7 files = new ArrayList ( ); Java 7 introduced ‘diamond notation’ files = new ArrayList ( ); where the type parameter can be inferred from the variable it is being assigned to myMusic: MusicOrganizer ...
Java Collections Framework JavaCollectionsFramework Liang,IntroductiontoJavaProgramming,SeventhEdition,(c)2009PearsonEducation,Inc.Allrightsreserved.0136012671 1 Objectives TodescribetheJavaCollectionsFrameworkhierarchy(§22.1).Tousethecommonmethodsdefinedinthe...
例题2(PPT 上例题) import java.util.*; class AlgorithmExample1 { public static void main(String args[]) { List<Integer> link = new ArrayList<Integer>(); link.add(new Integer(10)); link.add(new Integer(35)); link.add(new Integer(23)); link.add(new Integer(54)); link.add(new In...