arraylist | 易学教程

Java: Best way to remove duplicated list in a list [duplicate]

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问题 This question already has answers here : How do I remove repeated elements from ArrayList? (38 answers) Closed 2 years ago . I have a list of list: List<List<Integer>> myList = new ArrayList<>(); What would be the best way to remove the duplicated list in myList? For example, in the following list of list: [[-1,0,1],[-1,-1,2],[-1,0,1]] I would like to reduce it to: [[-1,0,1],[-1,-1,2]] Thanks! 回答1: The easiest way is to copy it into an order-preserving set (or, more generally, any kind of set

Displaying the values of an Arraylist with a JTable

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问题 I created a class named EmployeeGUI that is able to create any amount of user Employee objects and add them to an arraylist. The problem i have is that i have a JTable at the bottom of my GUI that i want to display all the objects that i've created but in my case the GUI Creates a new Table Object each time it goes through a for loop with the details of an object but as the for loop goes on the new details overwrites the old details rather than being added to the bottom of a jtable. Can

how to access Dictionary data within an Arraylist in Java?

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问题 I am creating Dictionary and an ArrayList such as this. Dictionary testDict, testDict2 = null; ArrayList al = new ArrayList(); testDict.put ("key1", dataVar1); testDict.put ("key2", dataVar2); testDict2.put ("key1", dataVar1); testDict2.put ("key2", dataVar2); al.add(testDict); al.add(testDict2); now my issue here is, how can I access the data within the dictionaries? Like for example how would I retrieve key1 from testDict using al? Many thanks in advance :) 回答1: As you can read in the Java

Getting value from Nested HashMap into another Map

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问题 Hi, I wanted to store key and value of a nested Map that looks like this: Map<ArrayList <String>, Map<String, Integer>> NestedMap = new HashMap<ArrayList<String>, Map<String, Integer>(); into another variable let say getKeyFromInsideMap and getValueFromInsideMap. So it would be the values of the inside Map String and Integer that am interested in accessing. How do I this in a code? I tried several examples here in the forum but I don't know how the syntax would look like. Could you please

sorting integers in a arraylist of objects

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问题 I'm starting with Java, and my problem is that I have an Arraylist of objects("Articulos", means Articles), and this object has properties (like name, price, etc...). I want to sort the Arraylist by the price of each object. Here's what I've tried. First, I fill the Arraylist manually: public static void Introducir_Articulo(){ Articulo a=new Articulo(); System.out.println("Codigo del articulo: "+(art.size()+1)); if(a.codArt==0){ a.codArt++; } else { a.codArt+=art.size(); } System.out.println(

Why can't I use my ArrayList variable outside FacebookCallback

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问题 Hi I am trying to implement Facebook login and getting friends list. I am storing my Friends'name and profile picture url into ArrayList<TaggedFriends> Where TaggedFriends class will have set and get methods. I am now working in Fragment class named MainFragment. Here, I am storing values into taggableFriends variable inside a FacebookCallback Session. But I can't access it to any other places I am trying to store it into SharedPreferences but when I try to store, it returning null value.

Java convert ArrayList to int array

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问题 I want to convert my arraylist to a double array[]. Why can't I cast with this method, what is wrong? public static void convert(ArrayList list, double array[]) { array = new double [list.size()]; for (int x = 0; x < list.size(); x++) { array[x]=(double) list.get(x); } } I get this error message String cannot be cast to java.lang.Double I have this peace of code that does not work if I change fropm raw type ArrayList to Double, maybe suggestions to change this code? getTest().addAll(Arrays

How to pass ArrayList<Custom_Object> from one activity to another in Android?

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问题 I am trying to send a custom object from one activity to another activity, but it's crashing when I call the start activity. Below is the snippet I used. My Activity implements Serializable ArrayList<CUSTOM_OBJECT> Cus_Obje_arraylist = new ArrayList<CUSTOM_OBJECT>(); Here is my intent : Intent inte = new Intent(getApplicationContext(), ListActivity.class); ` inte.putExtra("list",Cus_Obje_arraylist);` startActivity(inte); Please let me know why it's crashing or what alternate way I can use?

结对作业——WordCount进阶版

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结对作业——WordCount进阶版标签（空格分隔）：软件工程 Task1：Fork仓库的码云地址博客作业要求地址：https://www.cnblogs.com/happyzm/p/9626779.html 结对项目码云地址：https://gitee.com/holmec/PairProject-Java/tree/master/ 结队伙伴：201621123033 姚雯婷博客地址 Task2:PSP表格 PSP2.1 个人开发流程预估耗费时间（分钟）实际耗费时间（分钟） Planning 计划 10 20 · Estimate 明确需求和其他相关因素，估计每个阶段的时间成本 20 20 Development 开发 420 300 · Analysis 需求分析 (包括学习新技术) 60 30 · Design Spec 生成设计文档 20 25 · Design Review 设计复审 20 20 · Coding Standard 代码规范 40 10 · Design 具体设计 20 26 · Coding 具体编码 120 150 · Code Review 代码复审 20 25 · Test 测试（自我测试，修改代码，提交修改） 100 70 Reporting 报告 80 110 · 测试报告 20 25 · 计算工作量 10 15 ·

Manage strings in Map

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问题 I'm already first time using Map on java. I'm creating a project on the console where I create Strings with this structure: String = word1 word2 word3, code; //This code is a number, can be the same as the // Map's key. Then, each time I create a String like this, I save it into a Map. After creating and saving into the map one or more Strings, I have to be able to show them in the console, or to delete one of them. The problem I'm getting is that when adding one String to the map, is