How to make sure that a variable passed to a method isn't altered by the method? I know in C++ you can do something like
void aMethod(const Object &item) {
........
}
I know that you can stop a variable from being reinitialized in java by doing this
void aMethod(final Object item) {
.........
}
However, that won't stop it from calling a setter on the item or changing something in it. Is there some other keyword out there that can do this? I just found that java DOES recognize the const keyword but that it really is useless.
So, any practical way that const can be further approximated in java beyond using final?
I am trying to write a java program that prints out the number that is the mathematical constant e. As you input a number, the larger it gets , the closer it comes to 2.71828 . Here is my code:
//taylor series that prints out e^1=1+1/1!+1/2!+1/3!+..... import java.util.Scanner; public class taylor_1 { public static void main(String args[]) { Scanner input=new Scanner(System.in); int factorial =1;
I was just wondering about the equivalent of c function getchar() in java? I am trying to assign letters to array elements through input stream. A simple code in java that matches this code:
"final" makes sure the constant has the same value and prevents it from being changed. So why add "static" to make it a constant. I figured the reason a few weeks back but don't remember it now.
"Because X is a compile time constant, the compiler will Y"... But what exactly is a compile time constant? And how can we determine whether something is treated as such?Obviously, a compile time constant is a constant value that is known at compile time... ... Literals are, by definition, compile time constants -- as they are constants, known at compile time.
But the definition of a compile time constant is a bit more complex. To start, let's examine section 15.28 of the Java language specification.A compile-time constant expression is an expression denoting a value of primitive type or a String that is composed using only the following:
Literals of primitive type and literals of type String Casts to primitive types and casts to type StringThe unary operators +, -, ~, and ! (but not ++ or --)The multiplicative operators *, /, and %The additive operators + and - The shift operators <<, >>, and >>>The relational operators <, <=, >, and >= (but not instanceof)The equality operators == and !=The bitwise and logical operators &, ^, and |The conditional-and operator && and the conditional-or operator ||The ternary conditional operator ? : Simple names that refer to final variables whose initializers are constant expressions Qualified names of the form TypeName . Identifier that refer to final variables whose initializers are constant expressions
This is the full definition of a compile time constant. And as you can see, it contains more than just literals. In fact, literals are merely the first bullet point on the list. Also, note that a compile time constant can apply to any literal that is of primative or String type.The next few bullet points are the operations that can be applied to a constant at compile time. This list is actually pretty long, as it is possible to apply most of the operations at compile time. It may actually be easier to remember what can't be apply at compile time -- pre and post increment and decrement, instanceof operator, or any method calls, are not on the list.
The last few bullets are the most interesting. It is possible to use a variable in the expression -- provided that the variable is a compile time constant variable. So... what is a constant variable? Going back to the JLS (section 4.12.4 to be exact)..4.12.4 final Variables.A variable can be declared final. A final variable may only be assigned to once. It is a compile time error if a final variable is assigned to unless it is definitely unassigned (§16) immediately prior to the assignment.
We call a variable, of primitive type or type String, that is final and initialized with a compile-time constant expression (§15.28) a constant variable. Whether a variable is a constant variable or not may have implications with respect to class initialization (§12.4.1), binary compatibility (§13.1, §13.4.9) and definite assignment (§16).The last part of the definition is the relevant part (I still find it amazing that this is that well hidden in the specification). To be a variable that is a compile time constant, the variable needs to be...declared as finalhave a primative or String typeinitialized (on the same line as the declaration)assigned to a compile time constant expression.
I'm new to Java and have been stuck on how to use a final declaration statement once it's made. Below is a class I'm creating with the intention of calling it under a main method. I don't understand if I'm supposed to do anything else, like do some sort of get/set, or if the final static line is all I need. And, I don't know how I call it to the main method once I do.
public class Shirt//class name. { int collarSize;//data field. int sleeveLength;//data field. public final static String MATERIAL = "cotton";//final data field for material.
This problem is from Java . It asks me to convert a binary number in to decimal. How to program this in java? I am not able to find an effective algorithm to convert in to Java.
Assuming that x, y, and z are integer variables, which of the following three logical expressions are equivalent to each other, that is, have equal values for all possible values of x, y, and z?
(x == y && x != z) || (x != y && x == z) (x == y || x == z) && (x != y || x != z) (x == y) != (x == z)
None of the three
A. I and II only B. II and III only C. I and III only D. I, II, and III
I selected B, but got it wrong. I really think I need understanding boolean logic. The correct answer says something else but I don't get the logic. Here is the correct answer:
Answer Key : The following model answer has been provided to you by the grader. Carefully compare your answer with the one provided here.
Expression III is the key to the answer: all three expressions state the fact that exactly one out of two equalities, x == y or x == z, is true. Expression I states that either the first and not the second or the second and not the first is true. Expression II states that one of the two is true and one of the two is false. Expression III simply states that they have different values. All three boil down to the same thing. The answer is E.
In exercise 4, I get the same problem:
The expression !((x <= y) && (y > 5)) is equivalent to which of the following?
A. (x <= y) && (y > 5) B. (x <= y) || (y > 5) C. (x >= y) || (y < 5) D. (x > y) || (y <= 5) E. (x > y) && (y <= 5)
Exercise 4 ABCDE Incorrect Score: 0 / 1 Submitted: 2/10/2014 8:21pm Your answer is incorrect. Answer Key
The following model answer has been provided to you by the grader. Carefully compare your answer with the one provided here. The given expression is pretty long, so if you try to plug in specific numbers you may lose a lot of time. Use De Morgan's Laws instead:
!((x <= y) && (y > 5)) !(x <= y) || !(y > 5)
When ! is distributed, && changes into ||, and vice-versa
I have been stuck on this for the past 2 hours, basically we have to compare user input, put user input into an array and compare for equivalency. An example of the program:
Array 1 & 2 are equal Array 1 & 3 are not equal Array 1 & 4 are not equal.
This cannot be done by importing Java.util.Array at all!! (my research only find this to compare arrays ) which is why I am having trouble starting off. My code thus far:
import java.util.Scanner; public class Lab07b { public static void main(String[] args) { Scanner input = new Scanner(System.in); System.out.println("Enter Integer 1:"); int a = input.nextInt();
I need to create a Java program that takes an input a color code in HSV and outputs the equivalent RGB code and Vice versa.
Example: If you test on the color RED in RGB: Input: (255,0,0) Output: (0,100%,100%) If you test on the color RED in HSV: Input0,100%,100%) Output: (255,0,0)
I have tried running the java application without adding the site to site list in java security tab. But I get a sand box message as APPLICATION BLOCKED BY SECURITY SETTINGS. How to run the java application without adding the site to site list in java security tab.
I want to develop a Java program that uses OpenScript APIs to test my applications. The OpenScript framework automatically creates the Java Code so I was thinking of either using this code or create my own using the APIs.
I tried both options using NetBeans but I'm getting errors everywhere starting with the library import. I'm pretty new to Java so I'm sure I'm missing a lot of things here. I pasted the code below from the OpenScript framework that want to use in a stand-alone file for your reference.,
I've written a java application with several classes all in the same .java file. It works just fine. Now, I've broken it up so that each class has its own .java file. Still works fine. My next step is to put those classes into a package, but I'm not about to get the program to run.The .java source files are all in /home/user/src
I've set the CLASSPATH to /home/user/src..All of the source files have "package com.myfirm.program" on the first line.I compiled the application with:
the compiler created the directory: /home/user/src/com/myfirm/program and put all of the .class files in there.So how do I get the program to run? if I run from /home/usr/src
java File1
I get: Exception in thread "main" java.lang.NoClassDefFoundError: File1 (wrong name: com/myfirm/program/Program)
In Main.java, How can i call method in CircleCalculationMethod.java ?
Should I put everything in same folder ??Should i do something like "import CircleCalculationMethod.java"Should i do something like create a package ...
The title of Question might seem old and previously asked.But I have a Question that what is difference between javaSE and Java EE.Although I knew what comes under JavaSE and What is under JavaEE.But My question is that.
What happens when we add PATH in our Environment Variable How does Eclipse or Other IDE use it?
Second Question is.
For Java SE we declare a Path Variable but for Java EE we do not add any library?(I know we add some jar file like for Servlet(Servlet-api.jar) and for EJB(Ejb.jar),But What is actaul difference?
I know about coding in general, Java, C, Python, SQL etc. but I barely know anything about making code come together on the web. I have a vague idea about what things like libraries and frameworks are,I'm interested in making a web application with which relies on Java do to the data processing. The idea is that the user inputs some messages, clicks submit, the text is taken away and processed, and the results are displayed on the screen. I would like the UI to be smooth with a modern look and feel.
Also, I usually do programming on Windows but I could also use Linux, so if I'll come across any specific drawbacks using Windows.
When I try to convert this value, "Testingu2120" (along with UTF coed u2120)comes as a string as part of SOAP response. I need to convert this UTF-8 characters in to a symbol, in this case it is SM (Service Mark) symbol and show it on the UI.
How can we achieve this in JAVA?
I have four different UTF-8 character set to convert.
I would like my application to execute a command in cmd. The command looks like
start "" /D "C:Riot GamesLeague of LegendsRADSsolutionslol_game_client_sln elease s .0.1.55deploy" "League of Legends.exe" "8394" "LoLLauncher.exe" "" "spectator 95.172.65.26:8088 P3hNrXYZlaM3iJ9ximtzJWHbwLhvbimJ 953089676 EUN1"
So my question is how do I do this?
I tried this, (just copy paste the command):
package MyProject; import java.io.IOException; import java.io.InputStream; public class Cmd { public static void main(String[] args) { try { final Process process = Runtime.getRuntime().exec("start "" /D "C:Riot GamesLeague of
We started learning about tables and have a little program. The teacher gave us an excercise and doesn't works (not running), I receive too many errors. So any simple java program with tables with 20 numbers, that is giving random numbers?
Write a function (or functions) that given a collection of files will produce a sum of integers from each line of each file. Each file can have any number of lines from 1 to N. Each line can contain only one integer and no other alphanumeric characters. All of the numbers from all of the files should be added to the final result. The result is just one number.
For either, what we are looking for is:
1. Clear separation of concerns 2. Well defined objects / interfaces 3. Application of good OO design principles to solve the problem 4. No code duplication 5. Test Driven Development 6. Well refactored code 7. Well tested code
