I'm working on a small program to compare service levels, the user will input the service level 2 times (current and requested) and then the input will be scanned and compared and show a message.
For example:
current = 9*5 NBD (a)
requested = 24*7 SBD (b)
I want to know how in Java I can tell the compiler that (b) is greater than (a)
Because I want to use if statement like this
if (b > a) then show message.
I tried to use string.equals, but didn't help me too much.
I was not successful to convert string to number to do such comparison.
Try following statement
if(a.compareTo(b) > 0);
First thing: you can't override String.compareTo(), because it's final. you can create class with String field and write compareTo() for this class. This is not best idea.
But you can compare two strings by putting them into array and creating implementation of Comparator interface in sort() method.
String current = "9*5 NBD";
String requested = "24*7 SBD";
String[] test = {current, requested};
Arrays.sort(test, new Comparator<String>() {
#Override
public int compare(String o1, String o2) {
//Your impl goes here
return 0;
}
});
Where do these strings come from? Surely they must be from some kind of table that contains the service level details together with the cost of subscribing to that service level. What you want to check is whether the required service level costs more than the service level the client already has. Suppose the service level details come from a Map<ServiceLevel, BigDecimal> that gives the cost for a certain service level. Then all you need to do is:
BigDecimal costOfCurrentSL = serviceLevelCosts.get(currentSL);
BigDecimal costOfRequiredSL = serviceLevelCosts.get(requiredSL);
if (costOfRequiredSL.compareTo(costOfCurrentSL) > 0) {
// ... tell client he needs to purchase a top-up
}
Thank you all for the willing to help :)
After a lot of thinking I found another way which helped me a lot
I created 2 new integers and called them Values of what I need.
and used if statement, that if the entered is 9*5 NBD so the value will be zero, and if it is SBD, the value will be 1 and so on, then created new if statement to compare the values and show me a message if the A is greater than B, and it really worked.
Here is a part of my code
String WA_SLA = "", REQ_SLA = "";
int Va_WA_SLA = 0, Va_REQ_SLA = 0;
if(WA_SLA.equalsIgnoreCase("9*5 SBD"))
{
Va_WA_SLA = 1;
}
if(REQ_SLA.equalsIgnoreCase("9*5 NBD"))
{
Va_REQ_SLA = 0;
}
if(Va_WA_SLA > Va_REQ_SLA)
{
JOptionPane.showMessageDialog(frame,"Warranty SLA is Higher than Requested SLA " ,null, JOptionPane.INFORMATION_MESSAGE);
}
Thaaaaaaaaaaaaank you a lot
Related
I have a list of students and I want to bring only the leaderId on top of the same list following remains the remaining list items using Java Streams. I tried the below logic but it is not working as expected
List<Student> students = ....
Long leaderId = 123;
students.stream().sort((s1,s2) -> leaderId.equals(s1.getId()) || leaderId.equals(s2.getId()) ? 1: 0).collect(Collectors.toList());
Can anyone please give me some suggestion on this
Example
List of students:
[{id:121, name:"John"}, {id:131, name:"Susan"}, {id:123, name:"Jacob"}, {id:155, name:"Sunny"}]
Expected Output
[{id:123, name:"Jacob"}, {id:121, name:"John"}, {id:131, name:"Susan"}, {id:155, name:"Sunny"}]
You have to write your own comparator first which places the leader at the front of the list when sorted using it. Then you have to use it for sorting the list. I don't see any point of using the streams here, since the iterative code looks more simple and readable. Here's how it looks in practice.
static class LeaderFirstComparator implements Comparator<Student> {
final long leaderId;
LeaderFirstComparator(long leaderId) {
this.leaderId = leaderId;
}
#Override
public int compare(Student o1, Student o2) {
if (o1.id == leaderId && o2.id != leaderId)
return -1;
else if (o1.id != leaderId && o2.id == leaderId)
return 1;
else
return 0;
}
}
And the client code:
students.sort(new LeaderFirstComparator(leaderId));
Update
If the first object is the leader, then it should come before the second, hence returning -1 according to the contract. Otherwise, if the second object is the leader, then the first one should come after it, hence 1. If nether of the objects are the leader or both are leaders, then the original ordering is preserved. Thus returning 0.
As per the below comment, you can further simplify it to this one liner:
students.sort(Comparator.comparing(s -> s.getId() != leaderId));
If the leader has a concrete id equals to 123, yo can get it using only a filter
List leaderStudents = students.stream().filter(s1 -> leaderId.equals(s1.getId()).collect(Collectors.toList());
This question already has answers here:
Multiple if statements with single else statement
(2 answers)
Closed 6 years ago.
I want to fill the acts array with values of some enum. While iterating I want to input commands from console, but my if statements don't find any match and I always get the output "Incorrect".
My code:
Action[] acts = new Action[n];
for(int i = 0; i < n; i++) {
System.out.println("Enter act: ");
Scanner in1 = new Scanner(System.in);
String s = in1.next();
acts[i] = new Action();
if (s.equals("rotate_forw"))
acts[i].type = ActionType.RotF;
if (s.equals("rotate_back"))
acts[i].type = ActionType.RotB;
if (s.equals("shift_forw"))
acts[i].type = ActionType.ShiftF;
if (s.equals("shift_back"))
acts[i].type = ActionType.ShiftB;
else
System.out.println("Incorrect");
}
Your else clause applies only to the last if statement, so you get the "Incorrect" output whenever s.equals("shift_back") is false.
Your statements should be replaced with a single if-else-if...-else statement, so that "Incorrect" is only printed if all the conditions are false :
Action[] acts = new Action[n];
for(int i = 0; i < n; i++) {
if (s.equals("rotate_forw"))
acts[i].type = ActionType.RotF;
else if (s.equals("rotate_back"))
acts[i].type = ActionType.RotB;
else if (s.equals("shift_forw"))
acts[i].type = ActionType.ShiftF;
else if (s.equals("shift_back"))
acts[i].type = ActionType.ShiftB;
else
System.out.println("Incorrect");
}
You should also consider what you want to assign to acts[i].type when the input is incorrect. Perhaps you should throw an exception in this case.
While #Eran's answer is correct, I'd like to suggest a different approach that encapsulates the enum with the translation from the external coding. Consider this:
public class EnumDemo
{
public static enum ActionType
{
Incorrect(""),
RotF("rotate_forw"),
RotB("rotate_back"),
ShiftF("shift_forw"),
ShiftB("shift_back");
private String code;
private ActionType(String code)
{
this.code = code;
}
public static ActionType fromString(String code)
{
return Arrays.stream(ActionType.values())
.filter(v->v.code.equals(code))
.findFirst()
.orElse(ActionType.Incorrect);
}
}
public static void main(String[] args)
{
String[] testData = {
"rotate_forw",
"rotate_back",
"shift_forw",
"shift_back",
"junk",
null };
Arrays.stream(testData)
.forEach(t->System.out.printf("\"%s\" -> ActionType.%s\n", t, ActionType.fromString(t)));
}
}
This uses the fact that enum constants can have associated data. I've added an instance variable code to hold the external encoding of each enum value. Then I added a static fromString(String code) method to the enum that looks up the provided code in the list of values. For 4 possibilities a simple linear search, equivalent to your if-then-else cascade, works fine. If there were dozens or more I'd set up a Map<String,ActionType> to handle the conversion.
The search using streams bears some explanation.
First create a Stream of enum values
Filter it to contain only enum values whose code matches the desired code (there should be only one)
Pick off the first entry, which comes back in a Optional. If nothing was found (i.e. the code is invalid) the Optional will be empty.
Use the orElse method to return the value if it exists or ActionType.Incorrect if not.
At first glance this might look inefficient since one expects that the filter() predicate has to scan the entire stream even if the desired element occurs early. This is a really nifty feature of Streams -- all intermediate streams are "lazy", so the filter won't iterate over the entire list if it finds the desired entry early. See this question for details.
Output:
"rotate_forw" -> ActionType.RotF
"rotate_back" -> ActionType.RotB
"shift_forw" -> ActionType.ShiftF
"shift_back" -> ActionType.ShiftB
"junk" -> ActionType.Incorrect
"null" -> ActionType.Incorrect
The last testcase shows the code is null-safe.
The biggest advantage is that the mapping is in the same place as the enum itself, so you won't have to hunt for the code when you add or remove an enum value. Also you can't forget to define the mapping since it's required by the enum's constructor.
I'm writing a function where I'm essentially doing the same thing over and over. I have the function listed below
public String buildGarmentsString(List<Garment> garments)
{
StringBuilder garmentString = new StringBuilder(10000);
for(int i=0;i<4;i++)
{
garmentString.append(this.garmentProductId(i,garments.get(i).getProductId()));
garmentString.append(this.garmentColor(i,garments.get(i).getColor()));
for(int j=0;j<garments.get(i).getSizes().size();j++)
{
//check xxsml
if(garments.get(i).getSizes().get(j).getXxsml() >0)
{
garmentString.append(this.garmentSizes(i, Size.xxsml(),garments.get(i).getSizes().get(j).getXxsml()));
}
//check xsml
if(garments.get(i).getSizes().get(j).getXsml() > 0)
{
garmentString.append(this.garmentSizes(i,Size.xsml(),garments.get(i).getSizes().get(j).getXsml()));
}
//check sml
if(garments.get(i).getSizes().get(j).getSml() > 0)
{
garmentString.append(this.garmentSizes(i,Size.sml(),garments.get(i).getSizes().get(j).getSml()));
}
//check med
if(garments.get(i).getSizes().get(j).getMed() > 0)
{
garmentString.append(this.garmentSizes(i,Size.med(),garments.get(i).getSizes().get(j).getMed()));
}
//check lrg
if(garments.get(i).getSizes().get(j).getLrg() > 0)
{
garmentString.append(this.garmentSizes(i,Size.lrg(),garments.get(i).getSizes().get(j).getLrg()));
}
//check xlrg
if(garments.get(i).getSizes().get(j).getXlg() > 0)
{
garmentString.append(this.garmentSizes(i,Size.xlg(),garments.get(i).getSizes().get(j).getXlg()));
}
//check xxlrg
if(garments.get(i).getSizes().get(j).getXxl() >0)
{
garmentString.append(this.garmentSizes(i,Size.xxlg(),garments.get(i).getSizes().get(j).getXxl()));
}
//check xxxlrg
if(garments.get(i).getSizes().get(j).getXxxl() >0)
{
garmentString.append(this.garmentSizes(i,Size.xxxlg(),garments.get(i).getSizes().get(j).getXxxl()));
}
}
}
}
This is my garmentSizes function:
public String garmentSizes(int garmentNumber, String size,int numberToSend)
{
String garmentSizes = "&garment["+garmentNumber+"][sizes]["+size+"]="+numberToSend;
return garmentSizes;
}
I'm trying to figure out how I can get this done with a lot less code. I've read that with functional programming you can do things like pass in functions to parameters to other functions. After doing some reading online, I think I want to do something like this but I'm not sure how or what the best approach would be.
I have done some reading here on stack overflow and I've seen people mention using either the Command pattern or FunctionalJava or LambdaJ for trying to approximate this feature in Java. I've read over the documentation for the two libraries and read the Wikipedia Article on the Command Pattern, but I'm still not sure how I would use any of those to solve my particular problem. Can somebody explain this to me? As somebody that has never done any functional programming this is a bit confusing.
You could use local variables to decrease the amount of repetition. Say bySize = garments.get(i).getSizes().get(j) for example.
instead of size.getXxsml(), size.getXsml() etc. you could use an enum for sizes and loop on sizes.
The whole thing would then look like:
for(int j=0;j<garments.get(i).getSizes().size();j++) {
bySize = garments.get(i).getSizes().get(j);
for (Size s : Size.values()) {
if (bySize.get(s) > 0) {
garmentString.append(garmentSizes(i, s, bySize.get(s)));
}
}
}
The bySize.get(s) method could be implemented either with a switch that directs to the right method or directly in the enum and you could get rid of the getXsml etc. methods.
The only thing which differs between all your checks is this:
getXxsml/xxsml, getXsml/xsml, getSml/sml, etc.
If you could pass these values (as strings) to some upper-level method, and if
that upper-level method could eval i.e. execute these strings, then you can just
have an array of these values and pass that array to that upper-level method.
In Java, you can do something similar with reflection.
All these checks could indeed be simplified to much less
code through the use of reflection.
Look at:
java.lang.Class
java.lang.reflect.Method
java.lang.reflect.Field
java.lang.reflect.Constructor
and you will see what I mean.
From your code it appears that some Class has the following methods:
xxsml(), xsml(), sml(), med(), ..., xxxlg()
to get the amounts (?) available for each size.
You can design your data better, like this:
Have a "Size" type, that enumerates all sizes (could be Enum or some class with attribute String key)
Have a method that returns a List of all known sizes.
replace the above methods with amountFor(Size) This could be backed by a Map<Size, Integer>
For backward compatibility, you could rewrite the old methods along the lines:
int xxsml() {
return amountFor(Size.XXSML); // assuming you have a singleton instance
// for each well known size
}
Of course, in getGarmentString, you would then loop through the List of all known sizes:
for (Size sz : Size.getAllKnownSizes()) {
if (garments.get(i).getSizes().get(j).amountFor(sz) > 0) {
... do whatever must be done here
}
}
So I have a class full of junit tests and a class full of methods that perform binary operations. The tests are checking to see if I have the right values at certain points.
I am failing a lot of tests because of what I believe to be is the return type. For example I get the message
junit.framework.ComparisonFailure: null expected:<[000]> but was <[BinaryNumber#4896b555]>
If I'm understanding this it's saying that it was looking for an array containing 000 but it got a BinaryNumber (which is the required return type). To help clarify here is one of the methods.
public BinaryADT and(BinaryADT y) {
int[] homeArr = pad(((BinaryNumber) y).getNumber());
int[] awayArr = ((BinaryNumber) y).pad(getNumber());
int[] solution = new int[awayArr.length];
int i = 0;
String empty = "";
while(i < solution.length){
solution[i] = homeArr[i] & awayArr[i];
i++;
}
for(int indexF = 0; indexF < solution.length; indexF++){
empty = empty + solution[indexF];
}
System.out.println(empty);
return new BinaryNumber(empty);
}
Am I understanding this right? If not could someone please explain? I'd also like to point out that this is for my homework but I'm not asking for answers/someone to do it for me. Just a point in the right direction at most.
I will gladly clarify more if it is needed (I didn't want to bog everything down).
Also this is my first post on here. I tried to keep to the formatting suggestions but I apologize if anything is sub-par.
As suggested here is the test method
public void testAnd1()
{
BinaryADT x = new BinaryNumber("111");
BinaryADT y = new BinaryNumber("000");
BinaryADT z = x.and(y);
assertNotSame(x,z);
assertNotSame(y,z);
assertEquals("000",z.toString());
}
Whenever you see the output of "toString()" like ClassName#SomeNumber, then you can be sure that toString() method is not implemented for that class (unless toString() method implementation itself is not like this).
In your case, expected value is [000], but you are getting [BinaryNumber#4896b555].
Try to implement toString() method in BinaryNumber class and return the value from this method as per assertEquals() expects. This should solve the problem.
Can you show me your test code?
1.Your expected type is different from the actual type.
2.BinaryADT class didn't overide toString method.
I have the following code that defines a getParts method to find a given Part Name and Part Number in the system. Note that this code comes from our system's API, so if no one can help I'll just delete this question. I figured someone could potentially see a solution or help me along the way.
<%! private QueryResult getParts( String name, String number )
throws WTException, WTPropertyVetoException {
Class cname = wt.part.WTPart.class;
QuerySpec qs = new QuerySpec(cname);
QueryResult qr = null;
qs.appendWhere
(new SearchCondition(cname,
"master>name",
SearchCondition.EQUAL,
name,
false));
qs.appendAnd();
qs.appendWhere
(new SearchCondition(cname,
"master>number",
SearchCondition.EQUAL,
number,
false));
qr = PersistenceHelper.manager.find(qs);
System.out.println("...found: " + qr.size());
return qr;
}
%>
But I would like to allow the user more flexibility in finding these parts. So I set up conditional statements to check for a radio button. This allows them to search by part name and part number, find all, or search using a wildcard. However, I'm having trouble implementing the two latter options.
To attempt to accomplish the above, I have written the below code:
<%
String partName = request.getParameter("nameInput");
String partNumber = request.getParameter("numberInput");
String searchMethod = request.getParameter("selection");
//out.print(searchMethod);
QueryResult myResult = new QueryResult();
if(searchMethod.equals("search"))
myResult = getParts(partName, partNumber);
else if(searchMethod.equals("all"))
{
//Should I write a new function and do this?
//myResult = getAllParts();
//or is there a way I could use a for each loop to accomplish this?
}
//else if(searchMethod.equals("wildcard"))
//get parts matching %wildcard%
while(myResult.hasMoreElements())
{
out.print(myResult.nextElement().toString());
}
%>
Basically, it accepts user input and checks what type of search they would like to perform. Is there an easy way to pass all the values into the myResult object? And likewise for the wildcard search? Like I said before, it may be futile trying to help without access to the API, but hopefully it isn't.
Thanks!
You can (and should) reuse the function, but in order to do so, you will need a part name and number (as those are its input parameters). So for the multi-result options you will need to get a list/collection of part names+numbers and feed them individually to the function, then collect the result in the format that is most appropriate for your needs