" In terms of methods supported by the classes, the methods of StringBuffer and StringBuilder are identical. They only differ in whether the methods are synchronized or not. " - Oracle Certified Associate Java SE7 Programmer Study Guide
What does synchronized mean in this context?
public StringBuffer padSpaces(String first, String second)
{
final int MAX_SPACES = 75;
StringBuffer line = new StringBuffer(first);
int numSpaces = MAX_SPACES - first.length()- second.length();
for (int i = 0; i < numSpaces; i++)
line.append(" " );
line.append(second);
return line;
}
This is what I have so far but I can't find a way to align everything to the right .
Is it possible to combine two classes that I have defined to contain some of the same elements so that NetBeans stops giving me errors? I don't want to get rid of any necessary code, and if both classes are necessary, should I just rename one of them? One class is an ArrayList that I am using to write the information for employees entered to a text file "employee.txt." I also want users to be able to call on this information via employeeID in order to display employee information. The code is the following:
public ArrayList<Employee> getEmployees() {
// if the employees file has already been read, don't read it again
if (employees != null)
return employees;
employees = new ArrayList<>();
if (Files.exists(employeesPath)) // prevent the FileNotFoundException {
[code]....
The other class is a getEmployee class that I previously defined before attempting to read the information from the text file and display it in the console. It is as follows:
private void getEmployees() {
try {
// if the file doesn't exists, create it
if (!Files.exists(employeesPath))
Files.createFile(employeesPath);
BufferedReader in =
new BufferedReader(
new FileReader(employeesFile));
[code]....
So, I've been working on a school project for a couple days, and I have my code written out but I can't fix the compile-time errors. The prompt for it is here:
Write two programs: one using the String class and one using the StringBuffer class. Your programs should store a set of Strings in an ArrayList and print those Strings in the order by which they are added. The output of your programs should create a complete sentence.
I am stuck on the first program.Here's my code for the first program:
Java Code:
import java.util.ArrayList;
public class SentenceNormal {
public static void main(String args[]) {
String n1 = "My ";
String n2 = "favorite ";
String n3 = "football ";
String n4 = "team ";
String n5 = "is ";
String n6 = "the ";
String n7 = "Seahawks";
[code]....
I'm in the process of doing a module grade book project and I have a working program, however I have to sort the array of students created first of all by name and then if they are identical, by student ID. I've looked at the compareTo method on several websites and I still don't know how to implement it in my code.
My main is as follows;
public class CommandLineTest {
public static void main(String[] args){
String moduleTitle=Input.getString("Enter module title: ");
double cwPercentage=Input.getDouble("Enter coursework percentage: ");
double examPercentage=Input.getDouble("Enter exam percentage: ");
[Code] .....
I am trying to write a program where I input numbers and if both arrays contain the same numbers it prints out identical. If not it prints out not identical. The issue I am having is that it says I am missing return statement at the very end of my program (the last bracket).
I added the else at the very end before the return true and this was the error that occurred. However is I remove the else all it says is lists are not identical even if they are?
import java.util.*;
import java.util.Scanner;
import java.util.Arrays;
public class Tester {
public static void main(String[] args) {
java.util.Scanner input = new java.util.Scanner(System.in);
[Code] ....
I want to convert the StringBuffer in to String . I have used this code but gives compile error.
import java.io.*;
import java.util.*;
import javax.mail.*;
import java.sql.*;
public class REPLACE {
static StringBuffer s= new StringBuffer("ABCD");
public static void main(String args[]) throws Exception
[Code] ....
C:jdk1.6.0_04bin>javac REPLACE.java
REPLACE.java:15: cannot find symbol
symbol : method to_String()
location: class java.lang.StringBuffer
rep = s.to_String();
^
1 error
I have a question about an exercise of OraclePress.
public class OompahLoompah {
public static void main(String[] ar){
final StringBuilder str = new StringBuilder("I good! ");
str.insert(2, "look ").append("and nice");
str.insert(str.length(), "!!!");
str.delete(str.length() - 2, str.length());
System.out.println(str.toString().trim());
}
}
The correct output is "I look good! and nice!" , but i don't understand for what .
Why the trim () method does not work? Whether is working on an object String.
what is the difference between stringbuffer and string builder?
View Replies View RelatedHow can I replace each letter for example "abcde" to "edcba" with StringBuilder only and without the reverse tool. This is what I tried:
StringBuilder str=new StringBuilder("abcde");
int indexBegin=0;
int indexEnd=4;
for(int i=0;i<str.length();i++){
str.setCharAt(i, str.charAt(indexEnd));
indexEnd--;
}
System.out.println(str);
The output is:edcde with i understand why its wrong ,the last two letters already swap so it didnt take from the original str.
I'm using the JOptionPane to display and receive information to/from the user. In addition to this, I am using StringBuilder to receive inputs from the user and then manipulate (append) that input to display the desired output.
//Example
(JOptionPane): "Enter text"
(user input): Java is cool!
(program): *stringBuilder.append(" I love it!")
JOptionPane.showMessageDialog( );
.....
Psuedo-like code. The problem is that showMessageDialog(null, string) and not showMessageDialog(string, string). I want to display the enter text: " Java is cool! I love it! " in the JOptionPane. How do I accomplish this, since showMessageDialog only accepts (null, string).
I have written two methods called "contains" and "overlaps". The method "contains" is to detemine whether a point (x, y coordinate) is within the surface area of a square object. The location of the square objects is determined by the location of the upper left corner of the square.The method "overlaps" is to determine whether two square objects overlap each other.
I have written these as two separate methods. However I want to change the method "overlaps", so that it uses the method "contains" within it. I.e. using a method within a method. Thereby hopefully making the "overlaps" method a bit more clear and easy to read.
Java Code:
/** Returns true of the point with the coordinates x,y, are within the square. */
public boolean contains(int x, int y){
int sx = location.getX(); //"location" refers to a square object
int sy = location.getY(); // getX() and getY() are to find it's coordinates
// "side" is the side length of the square
if (x >= sx && x <= (sx + side) && y >= sy && y <= (sy + side)){
[code]....
Below is the main class of a project ive been working on, the goal is to start a countdown specified by the user. When the countdown reaches zero the base drops in the song that is being played. (Its not done yet) The main problem that arises is the fact that my song plays, and AFTER that, the timer starts.
Output:
Please input countdown in HH:mm:ss format.
00:00:41
Start?
Yes
The name of of the song is: Skrillex & Damian "Jr Gong" Marley - "Make It Bun Dem"
The time of base drop is: 00:00:41 //Song starts here
//Song is done
//Then timer starts
00:00:41
00:00:40
00:00:39
[code].....
I have following code. In this code CSClient is an interface. All methods of CSClient are implementaed in CSClientImpl class. Do I not need CS Client Impl imported in this code ?
How can I call getBranch() of CSClient, which is not implemented in CSClient as " this. getCsClient(). get Branch (new CSVPath(vpath), true);" ? This code works fine without any error in eclipse.
How can a method getBranch(), which is implemented in CSClientImpl class be used in this code without importing CSClientImpl ?
package com.rbc.teamsite.client;
import java.io.File;
import java.io.FileWriter;
import java.io.InputStream;
import java.io.PrintWriter;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
[code]....
Write the header for a method named send that has one parameter of type String, and does not return a value.Write the header for a method named average that has two parameters, both of type int, and returns an int value.
View Replies View RelatedI have seen these two methods of using ItemListener. I am curios which is better and why. What are the differences?
ItemListener a;
Choice ce = new Choice();
ce.addItemListener(a);
[code]....
I have had to create a text analyser. I have created the program but it is all within the main method. The specification states that I have to have at least two methods within my Program.
import java.io.*;
import java.text.SimpleDateFormat;
import java.util.*;
import javax.swing.*;
import javax.swing.filechooser.FileNameExtensionFilter;
public class Analyser {
public static void main(String[] args) throws FileNotFoundException,
UnsupportedEncodingException {
[code]....
Java Code:
package methods;
import java.util.*;
import javax.swing.*;
public class Methods {
public static void main(String[] args) {
// TODO Auto-generated method stub
char choicee2;
[Code] .....
I'm working on a side project, which will eventually hopefully be a Pokedex, and I've just been going to it at the end of every chapter and using the stuff I've learned to work on it.So I just read chapter 3, which is all about variables and teaches how to use arrays.
my question is, does an array have to be declared inside a method? Because I'm trying to create an array inside a class without any methods and without the main, and I continuously get errors. Here's a quick working of my code that won't compile.
class blah {
blah a[] = new blah[7];
a[0] = new blah();
}
The error message focuses on a[0] = new blah(); Telling me the 0 should be a ], the = is an illegal start of type, so on and so forth. The program compiles completely fine if it's within a method, like this:
class blah {
void a() {
blah a[] = new blah[7];
a[0] = new blah();
}
}
Or if I have public static void main (String[]args); But I'm trying to practice working outside of main.So does an array have to be within a method,
I'm reading from one file and writing it into another.I then want to delete the first file and use the second (it will get the first files name) .My sample java file works completely fine but it doesn't work on my actual file -it looks like it populates my test file like it should but it does not delete the original. Occasionally DMap.xml won't delete either - I try and rename it and normally I get the error of 'the file is open in Java platform SE binary' so the files is open somewhere - but I thought I had closed it correctly so have I done that wrong? I have put the basic code :
public class DeleteEnvironmentsWindow extends JDialog {
String xmlFile = "c:DMap.xml";
String fromFile =xmlFile
public void removeEnvironment(){
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
DocumentBuilder builder = null;
Document doc = null;
[code]....
Lets say in method 1 I want to print the numbers 1 - 10. Easy stuff. I then print that to the
PrintStream outFile = new PrintStream(new File ("output5_01")); I declared.
Now I'm in another methods, How do I print lets say 11- 20 without erasing the first methods printed results?
so my desired results would be
outFile
-------------------------------
(From 1st method) 1- 10
(From 2nd method) 11-20
As of now the second method always over writes the first. None of my books cover this and its very frustrating when the entire code is done but this won't let me write to the file
I'm new to Java, and I just created this script:
public class HelloWorld {
public static void main(String[] args) {
String firstLine;
String startUp;
int hour, minute;
[code]...
Every time I try to run this is eclipse, I only get the first part, so it reads in the console: "Hello, world. The time is now 9:15. I'm tired."I want it to read: "Hello, world. The time is now 9:15. I'm tired. (new line) Today is Wednesday."
know my code sample file of renaming a file and deleting an original file will work fine but when I use the code within my main java file - it appears to populate the file that I want populating fine but wont delete the origional. I have everything on my c drive so I can very easily keep track of what files I do and don't have.
Can using the same files in different methods cause problems? (Beginning Java forum at JavaRanch)
I have a requirement , as part of that i have to get one UI value (JSP/JSF) , due to code avaialability the value i can't get in JSP directly for that i uses Javascript that value have to pass to JavaBean method which return some string. Codes have given below :
JavaBean method:
public void setExchangeCurrency(String exchangeCurrency) {
this.exchangeCurrency = exchangeCurrency;
}
/**
* @return the exchangeCurrency
*/
public String getExchangeCurrency(String cutryCode) {
ResultSet resultSet = null;
String sqlQuery = null;
[Code] ....
I am trying to pass the values for UPPER_BOUND and LOWER_BOUND from the main method into the getValidNumber method. However, I'm not sure how to do this. The rest of the code is correct as far as I know, I just need to get the values for the bounds into the getValidNumber method. How would I do this? the notes in the main method explain what I need to do.
public static void main(String[] args) throws FileNotFoundException {
Scanner kb = new Scanner (System.in);
final double LOWER_BOUND = 0;
final double UPPER_BOUND = 100;
//Call the getValidNumber method, passing it the values LOWER_BOUND and UPPER_BOUND.
//Take the returned value and store it in a variable called num.
//Print out the value of num (here in the main method)
[Code] .....
public class demo
{
Public class static void main(String[]args) {
//Creating a variable that will be a reference to the object
Peoples person_one;
[Code] ....
I have assembled this code below that has a void method which will creat a new object. Problem I encounter is that in
Create_object(person_one);
the person_one has an error saying not initialized. I'm jus trying to learn on my own ways here and practice so may know what's wrong with this? I know I can use a return object from methods but what about this approach?