2) Specify what arithmetic operators to swap (+, -, /, *)
2) If an arithmetic operator is read (like a + sign etc) then we swap it with its opposite (- for example)
3) Once the swap is complete, the rest of the file stays the same even if more operators are in the file...it is then output to a file (I am going with 1mutation.java)
4) This is where it gets tricky....it then picks up where it left off to finish reading the + operators (or whatever was specified) and repeats steps 2-3 (but the operator that is already swapped gets left as it was / skipped) and the output is saved as 2mutation.java.
The most I have been able to manage is having it changed 1 operator or all of them at once. I deleted a lot of my work to start fresh / master one operator for the time being. Here is what I have:
This is the data file I am using. (see attached) The file should be .java or .cpp but I stuck with .txt for now. How to tackle this? Am I on the right track?
I am trying to encrypt a string using substitution cipher, the program doesnt show any errors but the output is not what is expected. On encryption it shows random characters whereas i want it to be encrypted by another letter. This is what I have done:
/* Encryption using substitution */
import java.io.*; public class SSExp1 { public static void main(String args[]) { char[] ip= new char[20]; char[] op= new char[20]; char key = '3'; String b;
This is a snippet code that im developing. (no source of it) . I am facing a trouble to extract file in the same directory as the source file (example: extract here option)
public class HelperAction { public static void unzip(String zipFilePath)throws IOException { File dir = new File(zipFilePath.substring(0,zipFilePath.length())); // create output directory if it doesn't exist if(!dir.exists()) dir.mkdirs(); FileInputStream fis;
I have a file(source.txt) that contains some texts. Now, the java code is to run through each line in the source file and check if that line begins with a number and if true, copy that line to the destination file(destination.txt). I have the code but I am not sure why I can't loop through each line in the source.txt file. Below is my java code:
public static void copyFile(File source, File destination) { BufferedReader br; try { FileWriter fw = new FileWriter(destination.getAbsoluteFile()); PrintWriter bw = new PrintWriter(fw); br = new BufferedReader(new FileReader(source)); String line = new String();
[Code] ....
As shown in the source.txt file, there are 4 lines in the file but when the execution gets to while ((line = br.readLine()) != null) , it executes to false.. Why this is so?
below is the source.txt file
12 is a number Green is bad 5 is not so cool you are right
Have the following .bat file that compiles the ReadMindWave.java source with jna and jfreechart. I get a javac error saying 'no source' when the .bat is run, as the .java source needs to be included in the .bat file. Where it goes in the following .bat file?
@echo off echo Compiling %1 with JNA and JFreeChart... javac -Xlint:deprecation -cp "C:jna-master*;C:jfreechart-1.0.19libjfreechart-1.0.19.jar;C:jfreechart-1.0.19libjcommon-1.0.23.jar;."%*
The file to compile is in C:MindWaveTestsReadMindWave.java
how to add an error message when my program can't find the file the user inputs.
For example:
Enter your source code: D:Data StructsProjectssrcHelloWorld (I didn't put .java on purpose) Exception in thread "main" java.io.FileNotFoundException: D:Data StructsProjectsAssignment 3srcHelloWorld (The system cannot find the path specified) at java.io.FileInputStream.open(Native Method) at java.io.FileInputStream.open(Native Method) at java.io.FileInputStream.<init>(Unknown Source) at java.io.FileInputStream.<init>(Unknown Source) at java.io.FileReader.<init>(Unknown Source) at HomeworkDriverFour.main(HomeworkDriverFour.java:14) //Can I get rid of the exception above and replace it with "File not found!"
Enter your source code:This is what I have so far:
import java.io.*; import java.util.*; public class HomeworkDriverFour { public static void main(String[] args) throws IOException { // TODO Auto-generated method stub
when i try to compile following source file, there is a error which states "MovieTestDrive is public, so must be declared in a file MovieTestDrive.java" i didnot understand. i am beginner in java;
class Movie { String title; String genre; int rating; void playit() { System.out.println("playing the movie"); } }
I am having hard time to grasp the concept of java as i am beginner. according to different sources found in internet, only one class is written in one source file. and all those class can be accessed through the main class. my question is
1.can we access one class present in one source file, through another class present in another source file [not through the class containing main method]?
2.can we create more than 1 class in same source file?is there special way to do it? i do get error always when i try to do so 3.can multiple classes contain main method? or should there be only single class containing it?
To compile this code(Something.java) from command line I want to use the following command,
javac org/apache/Something.class
And for the compilation to be successful, I'll have to be just above bin-folder because...
- > Only then my default class path will be (.) and java would automatically include A.jar and B.jar(the other way is to add the jar files using -cp argument, which I want to avoid in this scenario)
- > And for the import org.mycompanyX to work I'll have to be in the (.) directory.
Are my assumptions correct about how java find jar contents imported in a source file?
I have a question about the following snippet concerning the steps the javac compiler follows to compile a program:
[...]at first, searching a class within a package is discussed if the latter doesn't contain a full package name[...]
It is a compile-time error if more than one class is found. (Classes must be unique, so the order of the import statements doesn't matter.)
The compiler goes one step further. It looks at the source files to see if the source is newer than the class file. If so, the source file is recompiled automatically. Recall that you can import only public classes from other packages. A source file can only contain one public class, and the names of the file and the public class must match. Therefore, the compiler can easily locate source files for public classes.
However, you can import nonpublic classes from the current package. These classes may be defined in source files with different names. If you import a class from the current package, the compiler searches all source files of the current package to see which one defines the class. I don't quite understand the red fragment. I wondered if the word "import" nonpublic classes from the current package weren't a synonym for the word "use", since why would we want to import a class from the same package when compiler searches the current package automatically anyway?
However I wanted to test nonpublic classes that are contained in source file which name doesn't match the class name:
NonpublicClass.java:
Java Code:
package com.work.company; class NonpublicClass { public void description() { System.out.println("Working!"); } } mh_sh_highlight_all('java');
[Code] ....
Everything's fine when the source file names are the same as above. However, when I change NonpublicClass.java to a different name, there's an error "cannot find symbol" in:
Java Code: NonpublicClass v = new NonpublicClass(); mh_sh_highlight_all('java');
I noticed that the class file for NonpublicClass isn't even generated so that's probably the cause. If I change to the directory of the package the NonpublicClass is contained in and compile it directly, i.e. issue for example:
I am trying to complete this question. I understand the most of it but I haven't go a clue to read in the file name.
Full question: Implement a program that reads in a Java source code file and checks to see if it has balanced {}brackets. Your program should use a stack, implemented as a linked list, to check the brackets.
NOTE: you can use a reference called top which points to the head of the list. Your program should run as a command line program and should take a filename as an argument and print one of BALANCED or NOT BALANCED.
For example: c:> java checkBalanced "myProgram.java" BALANCED
Exception in thread "main" java.lang.NullPointerException at javax.swing.ImageIcon.<init>(ImageIcon.java:205) at GUI.<init>(GUI.java:26) at Apples.main(Apples.java:7)
i think the problem is to do with my images not being recognised. I put them in my source in User>...>workspace>src which is correct as far as i know. From what i know the images should show up if i look at my src file in eclipse but they dont. I tried changing the file type from .png to .jpg but it makes no difference.
How do i go about developing a simple arithmetic tester program which can be used to support young children improve their arithmetic skill. The program should accepts string data for the player's name and the number of questions they want to try, which will be entered by the user. The program should take in the following inputs from the user:
The name of the player, so that the game can refer to them by name in messages. The name must be between 2 and 20 characters inclusive.
The number of sums that the user wants to attempt. This number must be a whole number, and be between 2 and 50 inclusive.
The program must check that the values entered fall within the valid ranges. The program must also check that no empty strings are entered for names.
Once the player has entered their name and the number of questions they want to attempt, the game begins. The program must generate sums for the player.
The program should generate one question at a time and display the question for the user. The questions must involve two numbers and be either a multiplication, division, subtraction, or addition. For example, the following are all valid questions:
3 * 4 = ? 8 / 2 = ? 7 + 1 = ? 9 - 8 = ?
The first number, second number, and arithmetic operator (multiply, divide, add, subtract) should all be chosen randomly, the program should Generate a new random number for each of the three parts of each sum. this requires you to choose one of the four symbols based on which random number is returned.
A few checks must be carried out before a generated question is displayed to the user. If the question is an addition question, no checks are required. If the question is a multiplication question, no checks are required. However, checks are required for subtraction and division sums.
If the question is a subtraction question, the program must check that the second number is equal to or smaller than the first number. Whilst the second number is larger than the first number, new numbers should be generated.
I just cant seem to understand the order of precedence here.
class Test{ public static void main(String[] args){ int k = 1; k += (k = 4) * (k + 2); System.out.println( k ); } }
From what I have read compound operators have the lowest order of precedence... But the above piece of code makes the assignment k = 1 + (k = 4) * (k + 2) before evaluating the rest of the statement first.
It then evaluates (k = 4) and proceeds with the remained of the statement 1 + 4 * (4 + 6)....
I dont understand why the first k is assigned 1 but the remaining ks 4. Should they not all be 1 or 4 (I would have thought 4, since += has the lost order of precedence so is evaluated last)??
import java.util.*; public class TestArithmetic { public static void main(String [] args) { Scanner console = new Scanner (System.in); System.out.println("Enter First Number"); int x1 = console.nextInt(); System.out.println("Enter Second Number");
This is what I have so far, but I don't know how to continue:
import java.util.Scanner; public class ArithmeticComputation{ public static void main(String[] args) { Scanner stdin = new Scanner(System.in); int num1 = stdin.nextInt();
[Code] ....
I'm looking for a method that allows me to assign char into actual operators, so that I can loop through all the computation.
I have just started to learn programming in the book I am teaching myself from it said how would you write the following arithmetic expression with it being the quadratic formula but only the plus part of it in the plus or minus..
package javalearning; import java.util.Scanner; public class QuadraticFormula { public static void main(String[] args){ Scanner input = new Scanner(System.in); System.out.print("Enter value for B: "); double B = input.nextDouble(); System.out.print("Enter value for A: "); double A = input.nextDouble(); System.out.print("Enter value for C: "); double C = input.nextDouble(); double negativeOfB = -B;
So I have one set of If Else If statements. My program calculates just the first comboBox. It is retrieving all the values from the other comboBoxes but I do not understand where to place the other If statement structure so I can calculate the other values I have set for the other objects. I would not like to use a different class for each and I know I have my calculations done right below my current if statement. Could it be left there and where shall I place the other if statements so they get read by my arithmetic sequence?
public void actionPerformed(ActionEvent e) { Object source = e.getSource() ; int deckSiz = (int) Decks.getSelectedIndex() ; int wheelSiz = (int)Wheels.getSelectedIndex();
