Java
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Java does not recognize elements in ArrayList?
I have a program where I make an ArrayList to save some cab objects I always get an error. What I get from the message…… -
Java – cannot save integers in an object array
I want to parse the string in object [] into integer and save it in the same place, as shown below: public class ArrPa…… -
Java – the special behavior of ArrayList remove () – why?
When we delete - 1 and empty the ArrayList, it will throw concurrentmodificationexception. When we delete 0 from the s…… -
Java – how to create different classes for database connections
I am developing a spring startup application. I need a general class to provide me with database connections for all c…… -
Java – cut and stack arrays
I have an int array as input The length of the array is always 2 ^ n. I want to cut the array in half and stack it Rep…… -
How does the Java – XOR (^) exchange algorithm work?
This is a way to swap a and B without requiring a third variable I understand whether XOR means "true" or "false" in t…… -
How to prevent Java from separating JSON strings passed as command-line parameters into single subunits of args []
I want to pass this JSON string to the Java class through command - line arguments However, in each space, the string …… -
Why if comparison doesn’t work in Java
I create a hash table in Java This is part of my code while (table[pos]!=null) { if (table[pos]==key) { …… -
Java – is it better to use inline local variables or chain methods?
If I have a series of method calls, each value for the next call, I should store them in local variables, as follows: …… -
How to create a general placeholder function in Java and use the function as a parameter later?
I don't know how to express my question, but it's simple I want to create a generic placeholder function that takes a …… -
Java – @ before / @ beforeclass doesn’t seem to work, and the object represents null
I was learning JUnit and had a problem at the beginning At the beginning, I want to initialize the object that will be…… -
java. Lang.unsupported operationexception: cannot resolve property at index 13: typedvalue {t = 0x2 / D = 0x7f010046 a = – 1}
I work for Android attrs XML file adds an attribute for different color shades In styles In the XML file, I give these…… -
I should put Java stream Is the map function used with the switch statement?
I want to stream objects to different objects according to type Stream<Animal> animals = Arrays.stream(Arrays.as…… -
Java – (floating point value, integer value, long value) how to give unexpected results?
import java.util.*; import java.util.*; import java.lang.*; class Main { public static void main (String[] args) …… -
Why does the java compiler generate strange local variables and stack mapping frames? How can they be used to reliably determine variable types?
With the help of ASM framework, I create a Java bytecode detection tool, which needs to determine and possibly change …… -
How to retrieve parent objects by filtering from child objects in a Java stream
People are my root poja, and I have a list of phone numbers for my children String firstName; String lastName; Long …… -
Java – an alternative to if else statements when using double precision
According to the salary, I need to assign a specific tax rate to the employee object Salary is defined by annual salar…… -
Compilation of generic class using generic interface failed
As far as I know, the following code should run without any compilation errors However, when I run this program, I get…… -
Java – performance analysis using IntelliJ and debug in visualvm
I want to describe the test application launched by IntelliJ For analysis, I used visual VM I use the parameter - j-do…… -
Java – is the order of variables important in packet change read / write operations in Parcelable?
I have the following implementation of a Parcelable class: public class DemoModel implements Parcelable { private …… -
Java lambda – finds whether any string element of a list matches any element part of another list
I have two string lists A = {"apple","mango","pineapple","banana",... } B = {"app","framework",...} What I'm looking …… -
Java – algorithm – the largest left sub array with smaller elements
I'm developing a program. I need to get the index of elements in the integer array, so that all elements on the right …… -
Java – what is the difference between these generic statements?
See the English answer > is this raw type assignment type safe? List = new ArrayList(); 1 Map<String,Intege…… -
Java 8 option list collection list compilation error
I can't understand the difference Stream<Optional<Integer>> optionalStream = Stream.of( Op…… -
java – /google-play-services_ lib/AndroidManifest. XML parser exception: premature end of file
I'm trying to import Google play services into eclipse_ Lib, as they said in this tutorial（ http://developer.android.…… -
Traditionally, where do you store Java Class file?
I have a Java SRC folder where I store my Java file Then I use terminal to compile them and finally get them in the sa…… -
Java – replace the list of arrayadapters
I have a custom arrayadapter that uses ArrayList < orderedproductitem > For my listview In this listview, I have…… -
Java – how to protect yourself from parameter misalignment
Suppose I have this important method: int generateId(int clientCode,int dataVersion) { return clientCode * 2 + dat…… -
Java – JPA entities with collections return false to the contains method on detached members
I have two JPA entity classes, group and user Group. java： @Entity @Table(name = "groups") public class Group { …… -
Java – use jodatime to UTC to local time in milliseconds
I try to use jodatime to display transactions in a specific time period Our server requires the start date and end dat…… -
Java – unable to parse the import org. Org springframework. test. context. junit4. SpringRunner
I'm trying to solve this problem from now on But I still haven't solved it I just got out of spring IO downloads a spr…… -
Java – Android spinner has a different background for each line
I know this topic has been solved many times. I have found several such problems, but I can't meet my needs I want a l……