Passing Unknown Type To A Method And Returning It
Feb 20, 2014
So I want to know how in Java you can pass a unkown type into a method (type can be an int, double, or a user defined object) and return that unkown type.
example of what I want:
Java Code:
public (unknowntype)[] method2 ((unknowntype)[])
//Process Data
//unknowntype.process();
return (unknowntype);
} mh_sh_highlight_all('java');
I know in C you can use void pointers and in c++ we have templates but I do not know how java handles this. Also I want to know if it is possible to call a method in the unknowntype.
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Mar 5, 2014
Which method is used while passing or returning a java object from the native method?
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Feb 17, 2015
I'm a independent IT contractor. On 2 systems this week I've experienced an issue when attempting to download JAVA the file is of an unknown type in IE. See attached. Alternative browsers on the same machine function properly.
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Jun 5, 2014
I am totally new to Java. What is the purpose of this method?
Flow of the int x=3; like where does the 3 go step by step?
Passing Primitive Data Type Arguments (from oracle java tutorials)
Primitive arguments, such as an int or a double, are passed into methods by value. This means that any changes to the values of the parameters exist only within the scope of the method. When the method returns, the parameters are gone and any changes to them are lost. Here is an example:
public class PassPrimitiveByValue {
public static void main(String[] args) {
int x = 3;
// invoke passMethod() with
// x as argument
passMethod(x);
[Code] ....
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Oct 21, 2012
Primitive arguments, such as an int or a double, are passed into methods by value. This means that any changes to the values of the parameters exist only within the scope of the method. When the method returns, the parameters are gone and any changes to them are lost.
Reference data type parameters, such as objects, are also passed into methods by value. This means that when the method returns, the passed-in reference still references the same object as before. However, the values of the object's fields can be changed in the method, if they have the proper access level.For example, consider a method in an arbitrary class that moves Circle objects:
public void moveCircle(Circle circle, int deltaX, int deltaY) {
// code to move origin of
// circle to x+deltaX, y+deltaY
circle.setX(circle.getX() + deltaX);
circle.setY(circle.getY() + deltaY);
// code to assign a new
// reference to circle
circle = new Circle(0, 0);
}
Let the method be invoked with these arguments: moveCircle(myCircle, 23, 56)
Inside the method, circle initially refers to myCircle. The method changes the x and y coordinates of the object that circle references (i.e., myCircle) by 23 and 56, respectively. These changes will persist when the method returns. Then circle is assigned a reference to a new Circle object with x = y = 0. This reassignment has no permanence, however, because the reference was passed in by value and cannot change. Within the method, the object pointed to by circle has changed, but, when the method returns, myCircle still references the same Circle object as before the method was called.
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Apr 29, 2014
I'm new to Java and I have a problem with a method, I can't see the code of the method, I just have a jar, but it should return a boolean, something like this:
boolean band = false;
band = TestClass.testMethod("blabla");
// band = false
The problem is that the method seems that is returning nothing (band remain false), and if I initialize band to true:
boolean band = false;
band = TestClass.testMethod("blabla");
// band = true
band remain true, in other words, the value of band is never modified, the question is, how is this possible? because it should return the same value on both calls, true or false, no matter the initial value of the variable that is receiving the returning value of the method.
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Sep 25, 2014
I am working on a project which manages an airport's airplanes and flights based on user input. The method printFlights() - lines 133-134 - is returning null and I can't figure out why. The method is supposed to print information about each flight. The logic is identical to the printPlanes() method which is working successfully.
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Nov 18, 2014
Now that I have figured out how to return a single variable from a method I am on to the next step, I need to return 2 or 3 variables from a method. I have searched the internet on how to do this to no avail (am I doing the wrong search? I do not know) but what I need to do is return a second (and eventually a third variable)
Here is what I have
private static String Engine() {
String engine = "";
int enginePrice = 0;
System.out.println("Choose a engine size:");
System.out.println("[4] cylinder");
[Code] .....
Which does not work.
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May 20, 2014
I'm using apache POI to input data from a excel database. I have a method that is supposed to count the number of rows containing data so I can use that number to initialize an object array. It's returning one more than the actual number of rows and I can't figure out why.
public int getDataRange() throws IOException{
int rowCount = 0;
Iterator<Row> rows = sheet.rowIterator();
while(rows.hasNext()){
HSSFRow row = (HSSFRow) rows.next();
rowCount++;
[Code] .....
I get an array index out of bounds exception at the highlighted line.
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May 18, 2015
I am trying to return an array and I keep getting a null error. The below class sets the material numbers into an array and should return that array if called :
public class Jobs {
private int[] materialsNumber;
//change to parts and create another class that gets the materials for the parts
public int[] job1() {
materialsNumber[0] = 11960120;
[Code] ....
I later try to call the method. The program executes but stops after I println "test in loop"
public class PurchaseOrdersToParts {
private Jobs job = new Jobs();
int[] getPartsForPurchaseOrder(BigDecimal purchaseOrder) {
System.out.println("inside getparts");
BigDecimal testNum = new BigDecimal(123.0);
[Code] ....
This is the method that is calling the method in the GenerateOrdersToParts class
private PurchaseOrdersToParts purchaseOrdersToParts = new PurchaseOrdersToParts();
@Inject
PoRepository poRepository;
public GenerateShopJobTickets() {
[Code] .....
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Nov 18, 2014
So i have used the "remove()" method in conjunction with an iterator to remove an object from a HashSet in my program, and part of my exercise requires me to return said object. What I can do to return an object that has been removed using "remove()" method?
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May 8, 2014
Does the following code pass a value into a method?
/code
lnValue[x][y] = computelnValue();
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Nov 3, 2014
Can we pass more than one array in a method?
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Dec 25, 2014
I need to write a method that will consume string representation of Object type and will return one object of this type. How to set return type for the method in this case?
Here is exmaple :
public <?> identifyType(String typeString){
if (typesString.matches("String")){
return new String("");
}else if (typeString.matches("Integer")){
return new Integer(0);
}
//....etc..}
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Feb 28, 2014
Passing Information to a Method or a Constructor
They show a line of code that goes like this:
public Polygon polygonFrom(Point[] corners) {
// method body goes here
}
So from what I understand this is a constructor method for a Polygon object from the Polygon class. What I dont get is the name of the method polygonFrom()
Shouldn't a constructor for a Polygon just have the same name as the class? Because from earlier examples in the tutorial it seems to me that this is what has been done
For example:
public Bicycle(int startCadence, int startSpeed, int startGear) {
gear = startGear;
cadence = startCadence;
speed = startSpeed;
}
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Jan 30, 2015
Java SE Runtime Environment build 1.8.0..This is part of the code:
public static int addAddress (String[] number, boolean[] front, double[] total) {
int num = 0;
double ffee = 0;
/*boolean value = false;*/
[code]...
I have tried using the line of code commented out, /*boolean value = false;*/. However, another error is displayed. The compiler shows the following...
Inspection.java:33: error: incompatible types: boolean cannot be converted to boolean[]
front[num]= defineFront(num, value);
^
Note: Some messages have been simplified; recompile with -Xdiags:verbose to get full output error...I know that boolean values are by default stored as false, once you create the array. However, I'm having trouble passing the variable to the method.
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Oct 29, 2014
I am working on an independent project it is a simple little text based rpg that will run in a counsel window. I have an object for Character that is creating during a CreateCharacter method. I want the play to be able to enter a character that will open up a menu that displays things like the name and health and stuff of the character from the object created in CreateCharacter, but because I have it in a different class I don't know how to reference the object made in CreateCharacter.
I have it in 6 files
Character --- Object with getters/setters for things like name, age, race, class, ect
MainMenu --- Displays title and promts for new game and quit
CreateCharacter --- Walks through and sets all values in Character
Stats --- Keeps the players stats (health, attack, ect) in an array
Intro --- Beginning demo thing (not really important for this question)
Menu --- Displays all current user stats (Having issues with this one)
Example I have this in Menu
System.out.println("Name: " + ????.getName());
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Apr 22, 2014
How to pass the methods listed below.
public ArrayList<Person> findPerson(String searchFor)
^ this method is suppose to search an array and find whatever you search (numerical or alphabetical)
I have this
public ArrayList<Person> findPerson(String searchFor) {
Main.handleSearchPerson(keyboard, searchFor);
ArrayList<Person> matches = new ArrayList<>();
for (Person p : personList) {
boolean isAMatch = false;
[Code] .....
I am not sure if how i am searching the method is correct or how to pass that to another class to put it inside of a switch statement.
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Apr 22, 2014
How to pass the methods listed below.
public ArrayList<Person> findPerson(String searchFor)
^ this method is suppose to search an array and find whatever you search (numerical or alphabetical)
i have this
public ArrayList<Person> findPerson(String searchFor) {
Main.handleSearchPerson(keyboard, searchFor);
ArrayList<Person> matches = new ArrayList<>();
for (Person p : personList) {
boolean isAMatch = false;
if (p.getFirstName().equalsIgnoreCase(searchFor)) {
isAMatch = true;
[Code] ....
I am not sure if how i am searching the method is correct or how to pass that to another class to put it inside of a switch statement.
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Jun 13, 2014
Here I am taking response data from JSON using jackson API.I found a feature like using Jackson the properties can be set to bean properties.
private static String readUrl(String urlString) throws Exception {
BufferedReader reader = null;
try {
URL url = new URL(urlString);
reader = new BufferedReader(new InputStreamReader(url.openStream()));
[Code] ....
I got the correct output here. But now I want to generalize my method into a utility class so that I can reuse the same method for setting response data directly to respective beans as given below:-
My question is how will I pass the bean object in my utility class?
public static Object getResponseData(String response,[b]String bean[/b]) throws Exception {
ObjectMapper mapper = new ObjectMapper();
mapper.configure(DeserializationConfig.Feature.FAIL_ON_UNKNOWN_PROPERTIES, false);
JsonNode root = mapper.readTree(response);
[Code] ....
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Aug 12, 2014
I have a log in page accessed by: localhost/Security/Login.jsp
When I click a log in button, doPost() method is executed from Login.java and displays the contents from main.jsp.
However,its url on my browser is localhost/Security/Login.
Generally, the pattern is the address of Login servlet.
So if I click a button from main.jsp, error occurs because it is trying to locate a servlet from /Security/[Servlet name].
What I want is to change the url as I go to main.jsp to localhost/Home/main.jsp.
Is this possible?
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May 12, 2015
I need to pass advanced object into controller from JSP page, but I always get null result.It's a controller method:
Java Code:
@RequestMapping(value="admin-user-edit", method=RequestMethod.POST)
public ModelAndView editUser(@ModelAttribute(value="user") UsersEntity user)
{
if (null == user)System.out.println("User is null");
else
System.out.println("User name = " + user.getName() + " | Users id = " + user.getId());
ModelAndView view = new ModelAndView();
return view;
} mh_sh_highlight_all('java');
And this is a JSP page snippet. I need to choose some user from user list and pass it to controller.
XML Code:
<c:forEach var="user" items="${user_list}">
<tr>
<td><c:out value="${user.id}" /></td>
<td><c:out value="${user.name}" /></td>
<td><c:out value="${user.login}" /></td>
<td><c:out value="${user.status}" /></td>
[code]...
I tried to pass it through HttpServletRequest argument but all the same.
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Jan 24, 2014
I just kinda get stuck when it comes to passing values into constructors, using main method or static method functionality. In theory i kind of understand how it work but when i type it, it's totally different! I have to have a junit test too but i guess i could do that in the end.
I have attached the assignment. So, how to proceed with this:
public class Flight {
int flight_number, capacity, number_of_seats_left;
String origin, destination;
String departure_time;
double original_price;
[Code] ....
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Jun 18, 2014
currently I am doing my java web application project ,and it has following steps 1) Upload the txt files 2) java servlet gets the txt file's url , read the data and do the calculation 3) pass the results
I almost finished the second step , and working on the first step .Since there are so many input files at a given time , i have to use drag and drop method to get the file's location.how to pass file's path to servlet.( servlet code can read the data from the given txt file path )software used - tomcat and netbeans 8.0
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May 21, 2015
I stumbled upon a method that im not sure how to handle (yet).Below the code:
public DateTime() {
this.day = day(milliseconds);
this.month = month(milliseconds);
this.year = year(milliseconds);
this.hour = hour(milliseconds);
this.minute = minute(milliseconds);
[code]...
The two last methods stumped me. The return type to each is "DateTime", according to JUnit complaints.I know that I can use the "this" keyword to reference to the object. But how do I get these two methods to return the correct result?
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May 26, 2015
I have a problem with my code with Junit:
"The method infinityNorm(double[) is undefined for the Type Vektor."
This error pops up for both the euclidian norm and the manhattan norm.
Here is the code:
package de.ostfalia.gdp.ss15;
public class Vektor {
public static void main(String[] args) {
double[] array = {1, 2, 3, 4, 5, 6, 7, 8, 9};
System.out.println("Euclidian Norm: " + euclidianNorm(array));
System.out.println("Manhattan Norm: " + manhattanNorm(array));
euclidianNorm(array);
[code]...
What is the problem here?
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