Posts by Victor Stafusa • 63,338 points
1,321 posts
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7
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answers1621
viewsA: Difference between AWT and Swing in component rendering
There are two types of components involved, the components Heavyweight and the lightweight. The components Heavyweight rely heavily on details implemented in native code to work (i.e., C and C++)…
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3
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answer41
viewsA: Encapsulating instance structure
I don’t know if this is what you need exactly, but to achieve the purpose you ask, I would do the following: Filing cabinet "object.h": typedef struct obj_instance obj_instance; typedef struct…
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10
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answer372
viewsA: What formats are used to represent values (color, contrast, brightness) in digital images?
For in-memory images, there are several possible formats, basically according to the number of bits per pixel, which in general can range from 1 (black or white) up to 32 (8 for red, 8 for green, 8…
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answers1299
viewsA: build-impl.xml:930: The following error occurred while executing this line:
[From here I started to write as a comment, but I saw that maybe it serves as an answer]. I’ve seen Netbeans give out strange bugs when it corrupts its cache. Netbeans maintains a file cache so that…
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answer66
viewsA: Different values between variable without value and variable with null value?
The name of this is initialization. So you initialize the variable: int sum = 0; That is, initialization occurs when you declare a variable already assigning it an initial value. Already this way,…
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answer64
viewsA: Error inserting data with Hibernate
The problem seems to be the spaces in column names. If your database contains columns with spaces in names, use the ` to escape them. I mean, your XML looks like this: <?xml version="1.0"…
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answer577
viewsA: Query in Mysql does not order correctly
Let’s start with this consultation here: select id_plataforma from game_plataforma order by id DESC; Note that you are selecting a field while ordering for another field. This should not be what you…
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answer128
viewsA: Why do I have to run this code twice to rotate the 3d object?
Your question is not clear, but as I’ve handled Unity3d, I saw that’s what you’re talking about, not just C#. Let’s explain the code, line by line: var device3d = helixViewport3D.Children[0]; I…
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answers481
viewsA: Doubt with float
The number that comes after the % and before the . is the number of characters minimum that the number goes into the resulting string. For example: #include <stdio.h> int main(void) {…
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answer104
viewsA: Mapping active and disconnecting users to exceed 3 users
First, let’s assume you have a class IdUsuario representing (as the name says), the id of some user. This class must be immutable and must implement the methods equals and hashCode properly. If you…
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answers66
viewsA: Storing data that can be accessed outside the database itself, goes against the 1st Normal Form?
Not. The first normal way dictates that you can’t have multivariate columns, and that’s not what you’re having. Relevant topic for further clarification: What is database normalization? Once you…
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answer2562
viewsA: Target Unreachable, Identifier 'usuarios' resolved to null
Your mistake is here: <p:password id="senha" maxlength="8" size="10" value="#{usuarios.senha}" required="true" requiredMessage="O campo 'Senha' é obrigatório" validatorMessage="Informe uma senha…
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answers2310
viewsA: I cannot disable a checkbox with enable = false
The correct name of the property is checked for marked/unmarked and disabled for disabled/enabled. See and test in the example below: function teste1() { document.getElementById('teste').checked =…
javascriptanswered Victor Stafusa 63,338 -
5
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answer264
viewsA: Database column named with alias not found in WHERE clause
This is your original query, formatted in a more readable way: SELECT DISTINCT CONTAS.contas_id AS contas_id, CONTAS.contastipodetalhe AS contastipodetalhe, CONTAS.contas_nome AS contas_nome,…
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answers167
viewsA: How do I pass an array of structure pointers to a function?
Just change the preenche(&lista[5],5); for preenche(lista, 5);. Ah, I think in your scanf("%d",&(lista[j])->notas[j]); you really wanted to scanf("%d", &(lista[i])->notas[j]);. I…
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answers924
viewsA: Format String
You can do it like this: import java.util.Map; import java.util.HashMap; import java.util.Set; import java.util.TreeSet; class Main { public static void main(String[] args) { String templateTexto =…
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answer270
viewsA: Threaded barriers - Output snippet code
There are three threads in your program, the main, the b1 and the b2. The main thread starts the program by creating the other two. Note that the main thread invokes the constructor for the object…
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answer996
viewsA: GROUP BY - Display grouped result using WHERE as a condition in the same table - Mysql
First, creating a table per room is silly. Think about it, you could add a column containing the number of the room and with that would be enough a single table. In addition, the column…
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answers310
viewsA: Problem on condition when checking if user typed "n", "N", "s" or "S"
First, remember that identation is of fundamental importance in Python. Without using the correct identation, your program will not work. According to, if pergunta == "s" or "S" should be if…
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answer668
viewsA: Maximum number of options within the JSTL <c:Choose> tag
The number of clauses within the <c:choose> is, for practical purposes, unlimited. But you don’t seem to understand the idea of <c:choose>. It works in a similar way to a if full of else…
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answers446
viewsA: WEB Service in Java
Use @FormParam in place of @PathParam. With this, you can put JSON in the body of the request, since this is a POST.
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answer1021
viewsA: I would like to understand the use of an DTO with an Entity
In my view, your application is correct. Traffic an instance of Entity out of the Controller it is not usually a good idea to allow code to be written that tries to change it in an inappropriate way…
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answers1171
viewsA: Entitymanager or Session? What to use?
Hibernate first appeared in 2001. Among the object-relational mapping frameworks that emerged in Java, it was probably the most famous, complete and successful. It uses the Session. However,…
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answers176
viewsA: Termination of a Thread
When a Thread ends, it "dies" automatically, no action being required to finish it.
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answers89
viewsA: How to make a regex capture a large variation of a term? (HOUSE, House)
You can use the flag of CASE_INSENSITIVE. Behold this example working on ideone: import java.util.regex.Pattern; public class Main { public static void main(String[] args) { Pattern p =…
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answer79
viewsA: Code works sometimes yes and sometimes no
The srand(time(NULL)) should only be called once, in the main. In his randomized_partition, what happens if r and p are the same? The interval will be zero and will give division by zero. That’s…
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answer356
viewsA: Database Locked Sqlite/Java error
Are you opening the Connection and the PreparedStatement but you’re not closing them properly. If they are dropped and forgotten open, they are likely to end up causing errors like the one you are…
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answer1316
viewsA: How to Make Select Self Relationship N:N
SQL is like this: SELECT DISTINCT a.* FROM usuario a INNER JOIN usuario_has_usuario h ON a.idusuario = h.aluno INNER JOIN usuario r ON r.idusuario = h.responsavel WHERE r.cpf = '12345678910'; For…
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answers576
viewsA: Problem when performing Join in tables with generalization
A generalization relationship can be modeled in many ways. The way I think will serve you best is as follows:: The most generic table has some primary key. The most specific tables have the same…
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answer76
viewsA: Query with Java 8 parameter to generate random numbers using Collectors.toList()
Try to do so: private static int gerarNumeroAleatorio() { return (int) (1 + Math.random() * 60); } public static List<Integer> gerarAleatorio() { return…
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answers11298
viewsQ: How does Try-with-Resources work?
In Java 7, the concept of Try-with-Resources was added in the language. What is the Try-with-Resources? How does it work? What does it serve? How is it used? What problem does it aim to solve?…
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answers11298
viewsA: How does Try-with-Resources work?
Opening and closing resources in Java, up to Java 6, was a very tedious task to do and very error-prone. Close open resources (calling the method close()) often it is something that either ends up…
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answer1191
viewsA: Reading XLS in Java
Let’s divide the problem into two parts: Transform the spreadsheet into an array of Strings. Draw an array of Strings using System.out.println. Follows the resulting code: public String[][]…
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answer1144
viewsA: Find the angle between 2 vectors in 3d
The size (or magnitude) of a vector is calculated by the Pythagoras formula, i.e., the square root of the sum of the squares of each component of the vector. The scalar product of two vectors is…
luaanswered Victor Stafusa 63,338 -
10
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answer503
viewsA: Questions about Mysql integration with Java
It is necessary to create the class Conexaoand the classes DAO manually or there is some functionality in Netbeans that can configure the program’s connection to the database using the graphical…
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answer2446
viewsA: Find strings within *.txt files in C
What you need is: Open the input file. Determining the file size. Put all file contents in a string in memory. Look for Nome: in that string, finding the appropriate position. Separate the name in…
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answers221
viewsA: Error in CRUD UPDATE command - java.sql.Sqlexception: No value specified for Parameter 8
There’s no point in using the StringBuilder to build a String each time each method is called, always the same String will be built. Use a String Pre-made fixed is much better and simpler. Note that…
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answers383
viewsA: How do I manipulate the order of the files in an Arraylist?
Solution idea First, you have to see that the file names have the format prefix + suffix, where the suffix is a number. With this, we can arrange your files, first by prefix and then by suffix.…
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answer226
viewsA: Mapping an enumeration
Let’s assume that what you want to map is that the genera are from food. That is, an entity Alimento contains a List<Generos>. Try to do something like this: @ElementCollection(targetClass =…
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answers511
viewsA: Wsimport of multiple equal services with various unnecessary operations
To btafarelo response helped me a lot, but it still wasn’t the ideal solution. Also, this answer Soen’s helped me a lot, although it was not yet the complete solution. First, I took one of the Wsdls…
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answers511
viewsQ: Wsimport of multiple equal services with various unnecessary operations
In Java, I am using the wsimport tool. The process works. However there are some problems. I have to wsimport into the services of several different suppliers (all of them third parties, I have no…
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6
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answers29835
viewsA: What do I need to fix? [Error] Ld returned 1 Exit status
Your code has a lot of errors. First, the scanf takes a memory address as the second parameter. For example, this is right: scanf("%d", &peso); That’s not: scanf("%d", peso); Remember that in C,…
canswered Victor Stafusa 63,338 -
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answers93
viewsA: When I use this permission an error occurs in the WHOLE. What do I do?
Watch this: return TODO; Who is TODO? What is this? What do you eat? Where do you live? The answer is that TODO comes from the English to do which means "to make". That is, this is something that…
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answers451
viewsA: Difficulty in relating the SNIS municipalities to those of IBGE
There are several Brazilian municipalities that have the same name, I thought there were few, but the check the list of all of them, I’ve seen a lot of cases. I think the worst case is Bom Jesus,…
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answers558
viewsA: Save Image with Better Resolution
Try to replace that: foto = Bitmap.createScaledBitmap(foto, 200, 200, false); That’s why: foto = Bitmap.createScaledBitmap(foto, 1000, 1000, false); Alternatively, just remove this line and fail to…
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answers1673
viewsA: How to resolve this 'java.lang.Illegalargumentexception: Unknown Entity' when running this simple application?
The error is in your class User here: import org.hibernate.annotations.Entity; That would be right: import javax.persistence.Entity; And just for the record, I already had this same problem in 2010.…
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answers1688
viewsA: Execute PROMPT / CMD commands in Java
I think this place is wrong: comando_01 = "attrib -R -A -S -H /S /D" + caminho + "\\*.*"; I think that should be it: comando_01 = "attrib -R -A -S -H /S /D " + caminho + "\\*.*"; Observe the space…
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answer31
viewsA: Class variable in Java have the same behavior as in Ruby?
In Java, class variables are declared with static. In this case, the object to which this variable refers will be the same for all instances of the class. Effectively, variables declared with static…
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answer148
viewsA: Truncate tables with Cache
The on delete cascade should only be used in some instructions DDL (data Definition language), and not in instructions DML (data Manipulation language). That is, it is to use only where there is…
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answer574
viewsA: getch python returning without using
Your syntax is wrong at first: Instead of: from msvcrt import getch key = msvcrt.getch() Should be: from msvcrt import getch key = msvcrt.getch() Besides, this piece is suspicious: print(getch()) I…