I'm very new to Java, and I want to make a very simple login Java-program. Don't think about security issues and such in this example, I just need help to get it right. My "Account informations" has to be stored in an Array.  This is my code: -- MAIN --  import java.util.Scanner; public class BATM {  public static void main(String[] args) {     Scanner input = new Scanner(System.in);      String username;     String password;      System.out.println("Log in:");     System.out.println("Indtast username: ");     username = input.nextLine();      System.out.println("Indtast password: ");     password = input.nextLine();      users check = new users(username, password);      if(check.auth())          System.out.println("You are logged in");    }  }   -- users ---  public class users { private String username; private String password; private String[][] accounts = {{"jesper", "abc123"},{"christian", "abc123"}};  public users(String user, String pass){     username = user;     password = pass; }  public boolean auth(){     if((username == accounts[0][0]) &amp;&amp; (password == accounts[0][1]))         return true;     else         return false; }  }   I guess this should be a quite simple function, but for some reason the if-statment will never return "true".   What am I doing wrong?  Jesper.
93
I've been using the == operator in my program to compare all my strings so far. However, I ran into a bug, changed one of them into .equals() instead, and it fixed the bug.  Is == bad? When should it and should it not be used? What's the difference?
81621
If I write the following class:  public class Example {        int j;       int k;        public Example(int j, int k) {            j = j;            k = k;       }        public static void main(String[] args) {            Example exm = new Example(1,2);            System.out.println(exm.j);            System.out.println(exm.k);       }  }   The program compiles, but when I run the program, the main method will print out two 0s. I know that in order to say that I want to initialize the instance variables in the constructor I have to write:  this.j = j; this.k = k;   But if I don't write it, then which variable is evaluated (or considered) in the constructor (on the left and on the write hand side of the expressions)? Is is the argument or the instance variable? Does it make a difference?  Are there other cases where the use of this is obligatory?
38112
Here's the scenario...    if (entry.Properties["something"].Value != null)   attribs.something = entry.Properties["something"].Value.ToString();   While effective and working correctly, this looks ugly to me.  If I don't check for a null before performing the ToString() then it throws an exception if the property was null.  Is there a better way to handle this scenario?  Much appreciated!
83735
private void activateRecords(long[] stuff) {     ...     api.activateRecords(Arrays.asList(specIdsToActivate));   }   Shouldn't this call to Arrays.asList return a list of Longs?  Instead it is returning a List&lt;long[]&gt;  public static &lt;T&gt; List&lt;T&gt; asList(T... a)   The method signature is consistent with the results, the varargs throws the entire array into the list.  It's the same as new ArrayList(); list.add(myArray)  And yes, I know it's meant to be used like this: Arrays.asList(T t1, T t2, T t3)  I guess what I'm getting at, is instead of the varargs form, why can't I just have my old asList method (at least I think this is how it used to work) that would take the contents and put them individually into a list?  Any other clean way of doing this?
22625
MyClass[] array; List&lt;MyClass&gt; list;   What are the scenarios when one is preferable over the other? And why?
7172
What would be the best way to look in a string[] to see if it contains a element. This was my first shot at it. But perhaps there is something that I am overlooking. The array size will be no larger than 200 elements.  bool isStringInArray(string[] strArray, string key) {     for (int i = 0; i &lt;= strArray.Length - 1; i++)         if (strArray[i] == key)             return true;     return false; }
24218
Is this functionality going to be put into a later Java version?  Can someone explain why I can't do this, as in, the technical way Java's switch statement works?
12184
I'm trying to get an understanding of what the the java keyword this actually does. I've been reading Sun's documentation but I'm still fuzzy on what this actually does.
34548
I'm trying to make a class that will execute any one of a number of stored procedures with any amount of variables  Im using php and mysqli   My class enumerates an array and constructs a string based on the number of elements if any giving something like this CALL spTestLogin(?,?) for example I now need to bind the input from my array using somethin like this:  $stmt->bind_param($this->paramTypes,$this->paramValues);//paramValues is my array   Then if that works I can work on getting my results  Any ideas
9051
Check out the below program.   try {     for (String data : Files.readAllLines(Paths.get("D:/sample.txt"))){         String[] de = data.split(";");         System.out.println("Length = " + de.length);     } } catch (IOException e) {     e.printStackTrace(); }   Sample.txt:   1;2;3;4 A;B;; a;b;c;   Output:   Length = 4 Length = 2 Length = 3   Why second and third output is giving 2 and 3 instead of 4. In sample.txt file, condition  for 2nd and 3rd line is should give newline(\n or enter) immediately after giving delimiter for the third field. Can anyone help me how to get length as 4 for 2nd and 3rd line without changing the condition of the sample.txt file and how to print the values of de[2] (throws  ArrayIndexOutOfBoundsException)?
26106
I have webservice which is passed an array of ints. I'd like to do the select statement as follows but keep getting errors. Do I need to change the array to a string?  [WebMethod] public MiniEvent[] getAdminEvents(int buildingID, DateTime startDate) {         command.CommandText = @"SELECT id,                             startDateTime, endDateTime From                             tb_bookings WHERE buildingID IN                             (@buildingIDs) AND startDateTime &lt;=                             @fromDate";      SqlParameter buildID = new SqlParameter("@buildingIDs", buildingIDs); }
104197
When i create new User Account and login with that credentials, it gives me this problem if admin doesnt have set thier values yet !!!**  AllotmentList = [select id, Days_Remaining__c from PTO_Allotment__c where Year__c =:year and Employee__c=:EmployeeList[0].id LIMIT 100]; //access only Current user Allotment details                 //to handle Listoutof Bound Exception wrote if-else          if(AllotmentList.size()&gt;0)         {         requests.PTO_Allotment__c=AllotmentList[0].id;         requests.Days_Remaining__c=AllotmentList[0].Days_Remaining__c;         }         else         {             //write a code when AllotmentList is empty ....         }
93369
I'm trying to figure out how to make a function that can take an array as a parameter and sort it. I think it is done with positional variables, but I'm not sure.
43400
So far I've been using public void run() {} methods to execute my code in Java. When/why might one want to use main() or init() instead of run()?
79063
I have an ArrayList of objects in Java.  The objects have four fields, two of which I'd use to consider the object equal to another.  I'm looking for the most efficient way, given those two fields, to see if the array contains that object.  The wrench is that these classes are generated based on XSD objects, so I can't modify the classes themselves to overwrite the .equals.    Is there any better way than just looping through and manually comparing the two fields for each object and then breaking when found?  That just seems so messy, looking for a better way.  Edit: the ArrayList comes from a SOAP response that is unmarshalled into objects.
16473
Consider the class below that represents a Broker:  public class Broker {     public string Name = string.Empty;     public int Weight = 0;      public Broker(string n, int w)     {         this.Name = n;         this.Weight = w;     } }   I'd like to randomly select a Broker from an array, taking into account their weights.  What do you think of the code below?  class Program     {         private static Random _rnd = new Random();          public static Broker GetBroker(List&lt;Broker&gt; brokers, int totalWeight)         {             // totalWeight is the sum of all brokers' weight              int randomNumber = _rnd.Next(0, totalWeight);              Broker selectedBroker = null;             foreach (Broker broker in brokers)             {                 if (randomNumber &lt;= broker.Weight)                 {                     selectedBroker = broker;                     break;                 }                  randomNumber = randomNumber - broker.Weight;             }              return selectedBroker;         }           static void Main(string[] args)         {             List&lt;Broker&gt; brokers = new List&lt;Broker&gt;();             brokers.Add(new Broker("A", 10));             brokers.Add(new Broker("B", 20));             brokers.Add(new Broker("C", 20));             brokers.Add(new Broker("D", 10));              // total the weigth             int totalWeight = 0;             foreach (Broker broker in brokers)             {                 totalWeight += broker.Weight;             }              while (true)             {                 Dictionary&lt;string, int&gt; result = new Dictionary&lt;string, int&gt;();                  Broker selectedBroker = null;                  for (int i = 0; i &lt; 1000; i++)                 {                     selectedBroker = GetBroker(brokers, totalWeight);                     if (selectedBroker != null)                     {                         if (result.ContainsKey(selectedBroker.Name))                         {                             result[selectedBroker.Name] = result[selectedBroker.Name] + 1;                         }                         else                         {                             result.Add(selectedBroker.Name, 1);                         }                     }                 }                   Console.WriteLine("A\t\t" + result["A"]);                 Console.WriteLine("B\t\t" + result["B"]);                 Console.WriteLine("C\t\t" + result["C"]);                 Console.WriteLine("D\t\t" + result["D"]);                  result.Clear();                 Console.WriteLine();                 Console.ReadLine();             }         }     }   I'm not so confident. When I run this, Broker A always gets more hits than Broker D, and they have the same weight.  Is there a more accurate algorithm?  Thanks!
96971
What is the Java equivalent of PHP's $_POST? After searching the web for an hour, I'm still nowhere closer.