arraylist | 易学教程

Erroneous update of ArrayList records when a new record is added

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问题 I am trying to create a table of tasks and manipulate its contents. I am tackling with a bug I don't understand, and be very thankful for help. I applogoze for the length of the question, but trying to bring as much details as possible. The class tasksRepository stores the records, which are constructed in the class taskDef , as array list. The setTask () and getTask methods contains the add() and get() methods of the ArrayList class. The taskDef object's parameters are created using local

Writing data to jTable using file i/o

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问题 can you please look at my code and explain why my program is writing more entries to the array list? package pkg842994_ranganathan_vocabtrainerdossier; import javax.swing.JLabel; import javax.swing.JFrame; import java.util.ArrayList; import javax.swing.JOptionPane; public class EditLibraryUI extends javax.swing.JFrame { //Declare array list as public static because it needs to be accessed //in other classes public static ArrayList<VocabWord> LibraryWordsList = new ArrayList<VocabWord>(); int

removing duplicates from list of lists and preserving lists

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问题 I have an arrayList of arrayLists. Each inner arraylist contains some objects with the format (name.version) . { {a.1,b.2,c.3} , {a.2,d.1,e.1} , {b.3,f.1,z.1}....} For example a.1 implies name = a and version is 1. So i want to eliminate duplicates in this arraylist of lists. For me , two objects are duplicate when they have the same name So essentially my output should be { { a.1,b.2,c.3},{d.1,e.1} ,{f.1 ,z.1} } Note that i want the output in the exact same form (That is , i dont want a

Why is this array list removal code failing?

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问题 I'm trying to remove specific values from a listbox by passing the corresponding text, looking for it in the listbox, and removing that item. With this code: private void UpdateGUIAfterTableSend(String listboxVal) { ExceptionLoggingService.Instance.WriteLog("Reached frmMain.UpdateGUIAfterTableSend"); try { listBoxWork.DataSource = null; // <= It seems necessary to set this to null to circumvent "Value does not fall within the expected range" for (int i = listBoxWork.Items.Count - 1; i >= 0; -

why assign ArrayList to new ArrayList temp

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问题 I am looking at the code for Permutations problem on leetcode. For example, [1,2,3] have the following permutations: [1,2,3], [1,3,2], [2,1,3], [2,3,1], [3,1,2], and [3,2,1]. And I found there is one sentence ArrayList<Integer> temp = new ArrayList<Integer>(l); I have no idea why here needs to assign the "l" to "temp". And I tried current.add(l) direclty but gave me the wrong answer. Can you help me with this? public class Solution { public ArrayList<ArrayList<Integer>> permute(int[] num) {

How to display records in a JTable from an arraylist .TXT file in java MVC?

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问题 Currently, this is my main screen: ( ) I have 2 files: “patient.txt” and “treatment.txt” which hold records of multiple patients and treatments. What I’m trying to do is to display all of those records in a nice JTable whenever I click “Display Treatments” or “Display Patients”, in a screen like so: I am using an MVC model for this Hospital Management System (with HMSGUIModel.java, HMSGUIView.java, HMSGUIController.java, HMSGUIInterface.java files), and add records using the following code:

Java Web Services and returning Vector<Vector<Object>>

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问题 Little different from my previous question. I want to keep these as 2 individual questions (as the other one was answered). I have a web service which I want to pass back a Vector<Vector<Object>> or ArrayList<ArrayList<Object>> to the client. For this I have created a simple POJO class (thanks Abhisek Bose) for this called VectorWS . The implementation using the Vector is as follows: public class VectorWS { private Vector vector; public VectorWS() { } public VectorWS(Vector v) { vector = v; }

泛型真的会降低性能吗？

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在《 .NET,你忘记了么？（八）—— 从dynamic到特性误用》一文中，飞林沙同学提到，使用泛型会略微降低程序性能，因此在程序中使用List<Object>是不合理的行为，应该使用ArrayList。这一点和老赵平时的观点相悖，老赵一直提倡，在.NET 2.0之后，要尽可能使用List<T>，情愿是List<Object>也不要使用ArrayList。不过个中原因与性能无关，我们稍候再叙述。飞同学的文章让我有了将泛型与非泛型进行性能比较的想法。这个比较非常容易，不过也得出了一些非常有意思的结论。泛型容器与非泛型容器的性能比较首先，我们来比较一种最“纯粹”的泛型容器，它的目的是避免程序的其他方面对性能的影响。因此，这里我们构造两个最简单的容器，就是简单的模仿ArrayList和List<T>： public class MyArrayList { public MyArrayList(int length) { this.m_items = new object[length]; } public object[] m_items; public object this[int index] { get { return this.m_items[index]; } set { this.m_items[index] = value; } } public

Is it possible to add an array of images to canvas and then delete them?

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问题 Is it possible to add an array of images to a canvas and then delete individual images?So lets say I declare an ArrayList and add my images to it. I then draw them on the canvas.How can i delete just one image instead of them all?Is this possible? ArrayList<Integer> myImageList = new ArrayList<Integer>(); myImageList.add(R.drawable.image1); myImageList.add(R.drawable.image2); myImageList.add(R.drawable.image3); canvas.drawBitmap(myImageList[0], 300, 400, null); canvas.drawBitmap(myImageList[1

How to set the ArrayList<custom> data in to the ListView in another fragment which extends listView?

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问题 How to set the ArrayList data in to the ListView in another fragment which extends listView? Help will be much appreciated from you experts out there. Custom ArrayList takes int, string, string. I get the user input from two EditText's and add them to this ArrayList. When user re-enters, it should keep adding it to the ArrayList. Objective is to get all the entries from user and show it in a ListView in the next fragment. But only the two Strings from the ArrayList into String array for the