Reading Class Files And Search For Access To Blacklisted Classes?
Oct 14, 2014
I am currently building a Plugin system for an application and I wanted to add a little security feature.
I have read many tutorials on this and they basically all came down to the same answer:
"Its complicated: You need a custom class loader and security manager and ... and even then its still tricky"
So I thought, before I load the classes dynamically I will simply read the class files. Why bother with a SecurityManager or ClassLoader if I can simply whitelist all allowed classes and search for all illegal Class access before I even load anything.
I want to search for files using wildcards. After a lot of googling I found [URL] ..... I downloaded the .java files and put them in the same directory as my own java file. but now I don't know, how to include this java file.
I'm having difficulty understanding this small piece of code:
package food; public abstract class Fruit { private String color; private String tasteType; public void setColor(String color) { this.color = color; } public abstract void setTasteType(String taste); }
The above is an abstract class which describes the basic structure that every fruit should "extend".
The below is a concrete subclass of the Fruit class called Apple.
import food.Fruit; class Apple extends Fruit { public void setTasteType(String taste) { tasteType = taste; } }
Also do note that the two pieces of code are in different packages!
Upon compiling the Apple class I get the following error: Apple.java:4: error: tasteType has private access in Fruit tasteType = taste; ^
What I don't understand is this: I've given a non-abstract implementation to the "setTasteType" method in the Apple class and clearly setTasteType should have the authority to modify the private instance variables of Fruit. But it turns out I'm wrong.
I have a javafx class that has buttons and textfields. Here is the code for a button, and i want the button to make a new object but im having trouble setting the constructor
Label label = new Label("Type"); GridPane.setHalignment(label, HPos.RIGHT); TextField textField = new TextField();
Label label2 = new Label("First Name"); GridPane.setHalignment(label2, HPos.RIGHT); TextField textField2 = new TextField();
[Code] ....
after i create the object i will insert the object in an arraylist of person objects
I know that I need to use substrings, but I'm not sure how to implement them. All of the names are red in from the file "employees.txt".
Using the file Employees.txt
1) Scan the file and create user ids for each person according to the following scheme
a) Take the first and last character of the first name, convert them to upper case
b) Take the first and last character of the last name, convert them to upper case
c) Concatenate the results from a and b i) Example: John Brown would yield => JNBN
d) Add the length of the first name to the length of the last name, disregarding spaces
e) Concatenate the result from step c to the result of step d i) Example: John Brown would yield => JNBN9
f) Concatenate a four digit number to the end of this. i) The numbers should begin with 0000 and increment by 1 ii) Example: If John Brown is the fifth name in the list the resulting UserID would be => JNBN90004
2) Display the user ids in four columns with a width of 14
I have copied a wav file as explained in [URL] ..... When trying to play my new file, it runs but no sound is hear. My reading and writing class is as explained in another post in the site:
This is the function that reads the file:
// read a wav file into this class public boolean read(DataInputStream inFile) { myData = null; byte[] tmpInt = new byte[4]; byte[] tmpShort = new byte[2];
[Code] ....
I can't hear the copied wav file, but still the wav file is correctly copied...
public class Tester { public static void main(String[] args) { Product p1 = new Product(); p1.loadFromFile("Monitor.pr"); System.out.println("Actual: " + p1.toString()); System.out.println("Expected: Product [id=12345, name=Monitor, description=A freakin great monitor!]");
p1.setId(11111); p1.setName("another product"); p1.setDescription("Description of another product!");
[code]....
The expected output is what my program should be doing and the actual output is what it's doing instead. As you can see, my code works for the middle test. But I cannot understand why it won't load the first fileFor the second half, the id and the quantity are separated by a comma... I'm not really sure how to deal with that. As you can see, I tried using a delimiter, but it doesn't seem to be doing any good.
I have looked over other people code relating to files that are related to my actual studies in class. My teacher hasn't worked on a lot of file problems so I want to gain some understanding on it.
1.) I have this class with variables declared
import java.io.*; public class FileDisplay { private String filename; FileWriter outputfile; File Inputfile;
I'm aware that having a private variable would not allow that variable to be accessed outside the code. Vice versa, public variable would do that. The FileWriter and the File Inputfile is something I don't understand, especially have them in classes. What is the purpose of them?
2.)
public class FileDisplay { private String filename; FileWriter outputfile; File Inputfile;
[Code] ....
I have made this code here that opens the output and input file. If I make another method, how would I display the text onto that same file. Hard to clarify for me, but in each method do I just keep creating :
So I have a text file, and I want my Java program to store names from the text file. How do I do that? This is what I have so far.
Java Code: import java.util.Scanner; import java.io.File; BingoCard[] cards = new BingoCard[n]; //Array of BingoCard objects, n being the length of the Array Scanner sc = new Scanner(File("Names")); //Names is the name of the file for(int c = 0; c < cards.length; c++) cards[c] = new BingoCard(sc.nextLine); mh_sh_highlight_all('java');
Here's the constructor.
Java Code: private string myName; public BingoCard(String name) { myName = name; } mh_sh_highlight_all('java'); Whenever I compile, I get this error message.
while (key != 3) { if (key == 2) { System.out.println("Input from a file"); // System.out.print("Enter file name: "); // String str = expression.nextLine(); int i = 0; File file = new File(
[code]....
What I need to happen is the file gets read in, the file is in the form:
a * ( b + c ) / 2 + ( 8 * b ) a = 5 b = 10 c = 20 ( x + y ) * z x = 13 y = 21 z = 3
And so on. My code is supposed to start at the beginning and have output like:
Infix: a * b ( b + c ) / 2 + ( 8 * b ) variable values: a = 5 b = 10 c = 20
**It then needs to store the variable names along with their values in a hash table**
postfix: a b c + * 2 / 8 b * + value: 155
And it continues reading the file in the same fashion.
My issue is I am not properly extracting the variables and their values from the file. I have the variables in an array list actually, so I have those, but don't know how to efficiently navigate to the values, then store the character and value in a hash table, while protecting against possible blank lines within the file. Thus just calling nextLine()s and next()s wouldn't work to get to values because they would lead to an error.
I just can't seem to figure it out how to solve this inherently recursive assignment.The task is to check a directory path and read the files within that path; also, if there are more directories within it, we have to go deeper into those directories to read the files within them - if any. What you're looking at is my skeleton of the assignment:
public class SearchingForStrings {
public static void main(String[] args) { String path = "."; // Default File sf = new File(path); String mainDirectory = args[0]; // These two are just String keyString = args[1]; // command-line arguments
have to create a file named Lab13.txt. In the file I have 10 random numbers. I have to import the 10 numbers and have to Multiply all the numbers from Lab13.txt by 10 and save all the new numbers a new file named Lab13_scale.txt. so if the number 10 is in lab13.txt it prints 100 to Lab13_scale.txt. how do i get it to Multiply Here is what I have:
I want to read about a 100 files. There are 4 Categories of the files. I also want to create a Database of these files. The 4 Categories are my Columns. My question is how to it. I know what i want to do but not how to write in code.
In the program below I'm trying to read the contents of several .txt files in the same diretory and create a new .txt file containing all of the data from each file. My output is generated in the console however my .text file is blank.
public static void main(String[] args) throws IOException { String target_dir = "C:Files"; String output = "C:Filesoutput.txt"; File dir = new File(target_dir); File[] files = dir.listFiles();
How can I Cache the data I'm reading from a collection of text files in a directory using a TreeMap? Currently my program reads the data from several text files in a directory and the saves that information in a text file called output.txt. I would like to cache this data in order to use it later. How can I do this using the TreeMap Class? These are the keys,values: TreeMap The data I'd like to Cache is (date from the file, time of the file, current time).
import java.io.*; public class CacheData { public static void main(String[] args) throws IOException { String target_dir = "C:Files"; String output = "C:Filesoutput.txt"; File dir = new File(target_dir); File[] files = dir.listFiles();
My working directory is e:ajava. in package p1 i create two classes c1 and c2. net beans creates three files e:ajavap1srcp1, e:ajavap1srcc1, e:ajavap1srcc2. package runs without a hitch. i create another package p2 under e:ajava. i want to use class c1 in p2. pray what on earth should be my import statement in the p2 source code after the first statement 'package p2'. another related querry what should i include in my class path so as to gain access to c1 and c2 in source code of p2.
I am working on a project that requires me to build a database with random access file, representing products, the base product contains a name (about 30 characters), a price (double), and a quantity (integer). I have worked on this project for probably 15+ hours and have tried so many things and feel like I've barley made any progress...
The part i am really struggling with is taking the data from the text file and creating an object array with it using the product class. Once ive accomplished that, i have to use that data to create a random access file with the data. Here is the base Product class that must be used to create the objects for the array.
public class Product { public String pName; public String stringName; public double price; public int quanity;
[Code]...
these continue for about 40-50 entries, they are not seperated by a blank line though i had to add those so it would display correctly, each entry is on its own line with name seperated with spaces, then price after a comma, then quanity after the second comma.....
I am working on a project that requires me to build a database with random access file, representing products, the base product contains a name (about 30 characters), a price (double), and a quantity (integer). I have worked on this project for probably 15+ hours and have tried so many things and feel like I've barley made any progress...
The part i am really struggling with is taking the data from the text file and creating an object array with it using the product class. Once ive accomplished that, i have to use that data to create a random access file with the data.
Here is the base Product class that must be used to create the objects for the array.
public class Product { public String pName; public String stringName; public double price; public int quanity; //Constructor public Product( String pName, double price, int quanity )
[code]....
and then here is the data from the text file that i must extract to use to create product objects.
Dill Seed,938,34
Mustard Seed,100,64
Coriander Powder,924,18
Turmeric,836,80
Cinnamon (Ground Korintje),951,10
Cinnamon (Ground) Xtra Hi Oil (2x),614,31
Cinnamon (Ground) High Oil (1X),682,19
these continue for about 40-50 entries, they are not separated by a blank line though i had to add those so it would display correctly, each entry is on its own line with name separated with spaces, then price after a comma, then quanity after the second comma.....
I just want to be able to read type and weight in the Letter class I created (I created read out messages to check in the Letter class). I am able to read it with in the Mail class.
package org.mailprice.postage; import java.util.Scanner; public class Mail { static Letter letter;
I will like to add to the questions about constructors and its this. I have a class A with a constructor, i have a class B which initialize the constructor. also i have a class C which needs a variable in class A but doesn't need to initialize the constructor of A. the question how do i access the variable of class A without initializing the constructor.
