Scanner na=new Scanner(System.in); String s; out.print("enter the value in s="); s=na.nextLine();//entering value at runtime out.println("value in s="+s);//check here the value in s if(s=="ERROR")    out.println("error is received "); else if(s=="SUCCESS")    out.println("success is executed "); char c[]; c=s.toCharArray(); out.println("length of string s="+c.length);   in this case why if statement or else statement donot work  but if we input the value in string  at compile time it executes so why not at runtime we usually compare two values by '==' operator so why not we can compare two string by using this operator there are various other methods available for comparing two strings i mean that,s ok but why == operator is not suitable for comparing strings or why == operator fails to compare two strings
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?
102259
I need to search a string in the string array. I dont want to use any for looping in it  string [] arr = {"One","Two","Three"};  string theString = "One"   I need to check whether theString variable is present in arr.
92088
public class WrapperTest {      public static void main(String[] args) {          Integer i = 100;         Integer j = 100;          if(i == j)             System.out.println("same");         else             System.out.println("not same");     }     }   The above code gives the output of same when run, however if we change the value of i and j to 1000 the output changes to not same. As I'm preparing for SCJP, need to get the concept behind this clear. Can someone explain this behavior.Thanks.
23909
Looking for reviewers to suggest optimization and improvements, and to evaluate coding practices.  final class Variables {     private final int x;     private final int y;      Variables(int x2, int y2) {         this.x = x2;         this.y = y2;     }      public int getX() {         return x;     }      public int getY() {         return y;     }      @Override public String toString()  {          return "x = " + x + " y = " + y;     } }  public final class FindMissing {      private FindMissing() {};      /**  * Takes an input a sorted array with two variables that repeat in the  * range. Remaining variable are consecutive. and returns two variables that repeats  *   * eg: for a range of 1,2,3,4, a valid input is [1, 4], [1, 3] etc.  *   * @param a : the sorted array.  */ /*  * Why is start needed ?  * If start is not given then if a1 is empty how do we know if missing numbers were  * [1, 2] or [4, 5] ??.   */ public static Variables sortedConsecutiveTwoMissing (int[] a, int startOfRange) {     if (a == null) throw new NullPointerException("a1 cannot be null. ");      int low = startOfRange;     // calculating the highest value of the range. it needs to be 2 more than length since all elememts are consecutive.     int high = startOfRange + (a.length - 1) + 2;      int i = 0;     boolean foundX = false;     int x = 0;       while (i &lt; a.length) {         if (a[i] != low) {             if (foundX) {                 return new Variables(x, low);             } else {                 x = low;                 foundX = true;             }         } else {             i++;         }         low++;     }      return new Variables(x, high);  }  public static void main(String[] args) {         // unsortedConsecutiveTwoMissing         int[] a6 = {1, 4};         System.out.println("Expected 2 and 3, Actual " + sortedConsecutiveTwoMissing(a6, 1));         // unsortedConsecutiveTwoMissing         int[] a7 = {-4, -1};         System.out.println("Expected -3 and -2, Actual " + sortedConsecutiveTwoMissing(a7, -4));         int[] a8 = {-4, -3, -2, -1};         System.out.println("Expected 0 and 1, Actual " + sortedConsecutiveTwoMissing(a8, -4));         int[] a9 = {5};         System.out.println("Expected 4 and 6, Actual " + sortedConsecutiveTwoMissing(a9, 4));         }      }
2552
Possible Duplicate:          I've coded something like this:  public bool IsDataChanged() {                T value1 = GetValue2;     T value2 = GetValue1();      return (valueInDB != valueFromView); }   Right now the function doesn't compile with the error "Operator '!=' cannot be applied to operands of type 'T' and 'T'". What do I have to do to make this function work ?
104592
I am running some script which passing the string argument and I want to do if else statement shown as below:  if [ $1 != '' ] &amp;&amp; [ $2 != '' ] then      do something.....   but it shown Error too many argument. Why?
35663
My controller code is as follows -          for(String resStr : responseArray){             if(resStr.indexOf('r_error_str') != -1){                 responseString += resStr.substring(resStr.indexOf('=') + 1);                  responseString += '\n';             }         }   but when i display this 'responseString ' String using 'apex:outputLabel or apex:outputText or as Exception message '\n' is not converting in new line. Whole String is coming in one line.  Can anyone explain why is this happining
86373
Groovy adds the execute method to String to make executing shells fairly easy;  println "ls".execute().text   but if an error happens, then there is no resulting output.  Is there an easy way to get both the standard error and standard out?  (other than creating a bunch of code to; create two threads to read both inputstreams, then using a parent stream to wait for them to complete then convert the strings back to text?)  It would be nice to have something like;   def x = shellDo("ls /tmp/NoFile")  println "out: ${x.out} err:${x.err}"
16336
Given the following code (that doesn't work):  while True:     #snip: print out current state     while True:         ok = get_input("Is this ok? (y/n)")         if ok.lower() == "y": break 2 #this doesn't work :(         if ok.lower() == "n": break     #do more processing with menus and stuff   Is there a way to make this work? Or do I have do one check to break out of the input loop, then another, more limited, check in the outside loop to break out all together if the user is satisfied?
1905
I ran into an interesting (and very frustrating) issue with the equals() method today which caused what I thought to be a well tested class to crash and cause a bug that took me a very long time to track down.   Just for completeness, I wasn't using an IDE or debugger - just good old fashioned text editor and System.out's. Time was very limited and it was a school project.  Anyhow -   I was developing a basic shopping cart which could contain an ArrayList of Book objects. In order to implement the addBook(), removeBook(), and hasBook() methods of the Cart, I wanted to check if the Book already existed in the Cart. So off I go -  public boolean equals(Book b) {     ... // More code here - null checks     if (b.getID() == this.getID()) return true;     else return false; }   All works fine in testing. I create 6 objects and fill them with data. Do many adds, removes, has() operations on the Cart and everything works fine. I read that you can either have equals(TYPE var) or equals(Object o) { (CAST) var } but assumed that since it was working, it didn't matter too much.  Then I ran into a problem - I needed to create a Book object with only the ID in it from within the Book class. No other data would be entered into it. Basically the following:  public boolean hasBook(int i) {     Book b = new Book(i);     return hasBook(b); }  public boolean hasBook(Book b) {     // .. more code here     return this.books.contains(b); }   All of a sudden, the equals(Book b) method no longer works. This took a VERY long time to track down without a good debugger and assuming the Cart class was properly tested and correct. After swaapping the equals() method to the following:  public boolean equals(Object o) {     Book b = (Book) o;     ... // The rest goes here    }   Everything began to work again. Is there a reason the method decided not to take the Book parameter even though it clearly  was  a Book object? The only difference seemed to be it was instantiated from within the same class, and only filled with one data member. I'm very very confused. Please, shed some light?
56898
It is a bit odd we can't evaluate a  statement directly on SObjectType, so I am trying to determine conclusively which workaround is the most efficient.  Just to verify, I tried to compile this code:  void demo(SObjectType input) {     switch on input     {         when Account.sObjectType { }         when else { }     } }   And this code generates the error:     Schema.SObjectType is not a valid switch expression type   Bummer. There are workarounds however. The two most obvious that I have come up with:  void demoRecordInstantiation(SObjectType input) {     switch on input.newSObject()     {         when Account a { }         when else { }     } } void demoStringTyping(SObjectType input) {     switch on String.valueOf(input)     {         when 'Account' { }         when else { }     } }   Maybe there are others, so if there is an obvious approach I have missed which performs better or is more readable/maintainable, let me know.  My question is, what approach offers the best performance? If I am calling this method many times in a loop, is the SObjectType.newSObject method resource intensive? Or calling String.valueOf(SObjectType)? Should I consider caching these values?
21733
EmployeeNumber = string.IsNullOrEmpty(employeeNumberTextBox.Text)     ? null     : Convert.ToInt32(employeeNumberTextBox.Text),  I often find myself wanting to do things like this (EmployeeNumber is a Nullable&lt;int&gt; as it's a property on a LINQ-to-SQL dbml object where the column allows NULL values).  Unfortunately, the compiler feels that  There is no implicit conversion between 'null' and 'int'  even though both types would be valid in an assignment operation to a nullable int on their own. Using the null coalescing operator is not an option as far as I can see because of the inline conversion that needs to happen on the .Text string if it's not null. As far as I know the only way to do this is to use an if statement and/or assign it in two steps.  In this particular case I find that very frustrating because I wanted to use the object initializer syntax and this assignment would be in the initialization block... Does anyone know a more elegant solution?
4461
This prints 83  System.out.println(0123)   However this prints 123  System.out.println(123)   Why does it work that way?
110271
I am having trouble with bash. I am trying to put a command in an if statement and then compare it to a string.  This works perfectly.  echo $(ipcs | grep Shared | awk '{print $2}')   When I put it in an if statement I get some problems.  $ if [ "$(ipcs | grep Shared | awk '{print $2}')" -eq "Shared"]; then   echo expression evaluated as true; else   echo expression evaluated as false; fi bash: [: missing `]' expression evaluated as false  $ if [ "$(ipcs | grep Shared | awk '{print $2}')" = "Shared"]; then   echo expression evaluated as true; else   echo expression evaluated as false; fi bash: [: missing `]' expression evaluated as false  $ if [ "$(ipcs | grep Shared | awk '{print $2}')" == "Shared"]; then   echo expression evaluated as true; else   echo expression evaluated as false; fi bash: [: missing `]' expression evaluated as false   I tried ==, =, and -eq because I wasn't sure which one to use.
13663
Assume you have some objects which have several fields they can be compared by:  public class Person {      private String firstName;     private String lastName;     private String age;      /* Constructors */      /* Methods */  }   So in this example, when you ask if:  a.compareTo(b) &gt; 0   you might be asking if a's last name comes before b's, or if a is older than b, etc...  What is the cleanest way to enable multiple comparison between these kinds of objects without adding unnecessary clutter or overhead?   java.lang.Comparable interface allows comparison by one field only Adding numerous compare methods (i.e. compareByFirstName(), compareByAge(), etc...) is cluttered in my opinion.   So what is the best way to go about this?
37260
In C# and in Java (and possibly other languages as well), variables declared in a "try" block are not in scope in the corresponding "catch" or "finally" blocks.  For example, the following code does not compile:  try {   String s = "test";   // (more code...) } catch {   Console.Out.WriteLine(s);  //Java fans: think "System.out.println" here instead }   In this code, a compile-time error occurs on the reference to s in the catch block, because s is only in scope in the try block.  (In Java, the compile error is "s cannot be resolved"; in C#, it's "The name 's' does not exist in the current context".)  The general solution to this issue seems to be to instead declare variables just before the try block, instead of within the try block:  String s; try {   s = "test";   // (more code...) } catch {   Console.Out.WriteLine(s);  //Java fans: think "System.out.println" here instead }   However, at least to me, (1) this feels like a clunky solution, and (2) it results in the variables having a larger scope than the programmer intended (the entire remainder of the method, instead of only in the context of the try-catch-finally).  My question is, what were/are the rationale(s) behind this language design decision (in Java, in C#, and/or in any other applicable languages)?
40162
Please demonstrate how the ternary operator works with a regular if/else block. Example:  Boolean isValueBig = value &gt; 100 ? true : false;     Exact Duplicate: