Java
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java. Lang. outofmemoryerror: Java heap space error when executing millions of queries
In my application, I need to perform millions of queries on MySQL database The code is as follows: for (int i=0; i<…… -
Java run static method in new thread
I just started learning Java, and I encountered a slight obstacle involving threads I have a static method. I want to …… -
Java EE – GlassFish: name of driver class missing data source
(scroll to the end to find possible errors related to this.) This connection pool seems to be correct, at least Ping i…… -
Java: how to assign variables if the result is null?
This works: String address1 = HtmlUtil.escape(rs.getString("address1")); ... but I don't want to show "null" So I trie…… -
Java – array null pointer exception error
I continued my school project and seemed to have encountered another mistake So what happens is basically that I get a…… -
How does this java code work?
I have this code class NumberMachine { public static void main(String [] args) { Integer wi1 = new Integer("…… -
java – studio. SH denies open permission for Android studio in Ubuntu
I downloaded an Android studio for Linux, and then tried to run the studio according to the 'bin' directory in the ins…… -
Measure the size / length of a single linked list in Java?
I need help making int size(); The method of single linked list in Java This is me so far, but it doesn't return the c…… -
Java – deletes the last line from StringBuilder without knowing the number of characters
I wonder if there is a simple way to delete the last line from the StringBuilder object without knowing the number of …… -
Java – the best way to initialize ArrayList and HashMap?
Suppose I want to create an ArrayList for numbers The way I learn it is this: private static List<Integer> numbe…… -
java. Lang. numberformatexception: for input string: “23” [copy]
See English answers > what is a numberformatexception and how can I fix it? 9 PS I tried to solve the "Chef and str…… -
You need to display the date in the format yyyy / mm / DD in Java
I'm using nebulla datechoosercombo I use it as datechooserfrom getText();. It produces results such as 7 / 31 / 2011 i…… -
R: Delete the numbers at the beginning and end of the string
I have the following vectors: words <- c("5lang","kasverschil2","b2b") I want to delete "5" in "5lang" and "2" in "…… -
Java – database write lock entity in spring
When I am using its child entity, I need to write lock the parent entity so that it is not allowed to modify (or spars…… -
Java promotes the exact value of N from n to n
I have this simple question Sample input: Enter a 95.123 Enter two 12 Raising the first input to the second input must…… -
Java file to binary conversion
How to convert files to binary? I just need it for my project I need to encrypt the file through its binary file Solut…… -
Java – check in scope precondition
I like the premise of guava, but what I really need is another way - check whether the number is in the range SMT like…… -
How to deny that a value is the same as the value in Java [integer. Min_value]
How are these values the same in Java? -Integer.MIN_VALUE == Integer.MIN_VALUE The values are: -2147483648 : -21474836…… -
Java – the declaration of variable name declares the type of value to be stored? A prank?
Therefore, I have this true / false question in my computer science class (we use Java): (the word "type" in the quest…… -
Java, convert date to string and return the date that generated the error
I tried to convert date to string and then back to date But I find that the last date is different from the original d…… -
Java – sort arrays by time
First, I use an array to get such information: // Tuesday array[2][1] = "tuesday"; array[2][2] = "20:00"; // Wednesda…… -
Java – how to parse strings safely?
We know that using string join to form SQL query will make the program vulnerable to SQL injection attack I usually us…… -
How to check whether ArrayList contains 2 values?
Is there a way to check whether a collection contains one or more values and has better performance than using the con…… -
Java – propertynotfoundexception when using JSTL with Boolean value
I have a filebean that renames Boolean variables It has the following code public class FileBean { private boolea…… -
Java – resteasy @ path with zero or more path parameters
I use resteasy. Com in API development My website is http: / / localhost: 8080 / project / player / m or http: / / loc…… -
Java garbage collection scenario
I'm going through the Java garbage collection process and different scenarios for GC The following is what I am confus…… -
Java – provides multiple types of sorting for objects
Suppose I have a Java object with multiple string fields public class Person { private String field1 // keeps …… -
Java,UnsupportedClassVersionError. How can I solve this problem
I was doing my homework during the solar eclipse. It didn't report an error or even a warning When I tried to compile …… -
Clojure – why can’t let be used with vector?
replace (let [x 1] (my-expression)) I'm trying to use: (let (vector x 1) (my-expression)) Don't ask why, I prefer ordi…… -
Java – returns the primary activity from any activity on the Android application
I'm developing an Android application with an action bar and a dashboard When the user clicks the "application logo" b…… -
Java – how to handle tags in Android
I've been looking for some time and haven't been able to find the right answer for this one To make a long story short…… -
Java – builder pattern: why do we need it build()？
When studying the builder pattern, the standard pattern is as follows: new SandwichBuilder().salami().pastrami().cat()……