I want to clarify it whether this below code, when running this loop, will it create separate string objects as strings are immutable or else, will it keep the same reference(as each time inside loop, we use the same name 'rslt') and assign new string value for this?
while(inc < numberOfColumns){
String rslt=rs.getString(inc+1);
rowArr[inc] = rslt;
inc++;
}
strings are immutable in java...so can we apply toupper nd tolower function directly in a string
View Replies View Relatedhow to create dynamic string array if we dont know number of strings in the beginning?
View Replies View RelatedI would like to understand why only String class is immutable.
1. Why String class is immutable? What is the main reason for making String class as immutable.
2. Why there is no int pool or float pool or Integer pool etc, why only String pool.
I am a java fresher. I want to know weather String is immutable in Java or not .....
View Replies View Relatedthis is my code :
String name = "Mohan";
String is a immutable class and where these character stored when we assign some character. How the logics are working inside the String class.
public static void main(String[] args) {
String str1="Java";
str1="one";
System.out.println("str1="+str1);
}
String object is stored in a private final char array in String.java.
private final char value[];
The basic characteristic of a final variable is that it can initialize a value only once. By marking the variable value as final, the class String makes sure that it can’t be reassigned a value.
so the String objects can be initialized only once but the above code shows that str1 was initialized first with "Java", then it can be re-assigned value "one" bcos the output is one. If it can be re-initialized, basic characteristic of final variable is not satisified and hence how can we call String objects are immutable?
-I created the project with the checkbox "Create separate folder for sources and class files."
-I've tried running the program with the "mfq.txt" file in the root directory, the src directory, and the bin directory.
-I've even tried it in all three directories at once!
-I've also refreshed my project after each change in eclipse
-My error is the "FileNotFoundException" error
Here is the line giving me trouble
Scanner file = new Scanner(new File("mfq.txt") );
Where my code is wrong/where I should put my file? :tax:
An array has objects with String firstName, String lastName, int ID, char examType('M' or 'F'), and int score. Every object has both Midterm('M') and Final('F'). The array has to be sorted by the first Midterm- 'M' and immediately followed by the Final ('F') of the same person (object). Im having troubles with coming up with a proper algorithm with gettin the Final- 'F' after Midterm for the same person.
Java Code: public static Exam[] collateExams(Exam[] exams) {
Exam [] r = new Exam[10];
r = exams;
int[] position = new int[10];
int index = 0;
for(int i = 0; i < exams.length; i++)
[Code]...
I am having trouble with methods. What I want to do is be able to create 4 types of strings under the same method, but only draw one of them at a time.
i.e
UI.initialise;
UI.addButton ("pipe", this::drain);
public void drain(){
this.pipe ("pipe1");
this.pipe ("pipe2");
[Code] ....
When I press the button "drain" it will print=
pipe1
pipe2
pipe3
pipe4
I am having a lot of difficulty just printing one out after each time I press drain.
"drain"
pipe1
"drain"
pipe2 etc..
I'm having trouble creating two new die objects for the PairofDie class. I'm trying to run two separate die and print the face value and then add both numbers up and print those values as well.
public class Die {
private final int MAX = 6;
private int faceValue;
//private int faceValue2;
public Die(){
faceValue = 1;
[Code] .....
Exception in thread "main" java.lang.Error: Unresolved compilation problems:
The method Die() is undefined for the type PairofDice
The method Die() is undefined for the type PairofDice
at PairofDice.main(PairofDice.java:6)
I keep getting this as a result:
Exception in thread "main" java.lang.RuntimeException: Uncompilable source code - Erroneous tree type: myprojects.Balloon
at myprojects.BalloonTester.main(BalloonTester.java:1 8)
Java Result: 1
Is it possible to use a loop to create objects? I'm trying to put together a program (just as a way of learning) to run a horse race.
What I'd like to is have the user enter the number of horses they want in the race, and then create the objects as the user enters the various attributes of the horse (at least the horse's name), and then once all the instance variables have been set, create the first horse object and then move on to the second one, etc, until all the horse objects have been created.
I know I can't use something like a for loop to do it, so how would the code be writte
Our instructor gave us a list of steps to complete after creating a Balloon, but I can't get past just creating it. Search results have brought up other Balloon thread, however I couldn't find a topic about issues just creating the balloon.
package myprojects;
ublic class BalloonTester
{
public static void main(String[] args)
{
Balloon redBalloon = new Balloon("Red Balloon", 100);
[code]....
I'm stuck with the following error message when i try to convert a String to XML and back to a String.
Exception in thread "main" org.w3c.dom.DOMException: WRONG_DOCUMENT_ERR: A node is used in a different document than the one that created it.
at com.sun.org.apache.xerces.internal.dom.ParentNode.internalInsertBefore(Unknown Source)
at com.sun.org.apache.xerces.internal.dom.ParentNode.insertBefore(Unknown Source)
at com.sun.org.apache.xerces.internal.dom.NodeImpl.appendChild(Unknown Source)
at com.innovatrail.consulting.xml.XMLTEST2.main(XMLTEST2.java:66)
Below is my Java code snippet: The code syntactically correct except line 66. If you comment out line 66 in the source code, everything works just fine. The XML representation of my input string is denoted by INPUT 1 and that of my output string is denoted by OUTPUT 2.
package com.Test.xml;
import java.io.ByteArrayInputStream;
import java.io.StringWriter;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.transform.Transformer;
[Code] ....
INPUT 1:
<Collection>
<BookList>
<Book>
<Title>Wonder Man
</Title>
<Author>John Smith
</Author>
<Category>Fiction
[Code] .....
OUTPUT 2:
<Collection>
<Book>
<Title>Wonder Man</Title>
<Author>John Smith</Author>
<Category>Fiction</Category>
[Code] ....
how String objects are different from other objects
part 1:
// creating two objects
Dog mydog1 = new Dog();
Dog mydog2 = new Dog();
// comparing the reference variables
if( mydog1 == mydog2){
System.out.println(" The reference variables refer the same object ");
}
else {
System.out.println(" They refer to different objects ");
}
The above code works as I understand objects , it prints "They refer to different objects " to the screen.
Part - 2
// creating two objects ( I beleive, pls correct me if i am wrong )
String a = "haai";
String b = "haai";
if( a == b){
System.out.println(" Reference variables refer to same object");
When i run the above code it prints that a and b refer same object , I don't understand how they refer to same object when i didn't assign " String b = a; ". My question is did java just create one object and stored the same reference values to a and b .
I am trying to update a Rubik's cubes side by adding each of the 9 squares of the Rubik's cube's side.
So for example:
cube.front.squares = cube.fronts.squares[1] + cube.front.square[2] + cube.left.sqaures[8] ... //until 9 sqaures are added, where squares is a String array of size 9. However, when I try doing this I get an error stating "change 'square' to 'String'". I know I can go in an individually change the values like:
cube.front.squares[0] = "whatever"
cube.front.squares[1] = "something else"
but I know there is a better way to do this...
I also just tried to use String[] concat= ArrayUtils.addAll(first, second) but that only takes in two arrays at most according to the API: [URL]...
Now I am trying to print the 4 string randomly from string array..where string contains no of words which are splitted from the file....
View Replies View RelatedString str = "#11* 1# 2*12# 3"
required o/p in array as
#11
* 1
# 2
*12
# 3
i.e splitting the strings for every 3rd string and storing it in an array of strings ...
Im looking for a means to store groups of static data..
so I understand these simple string arrays...
Java Code:
private static String[] names = new String[] {
"aidanmack",
"johnsmith"
}
private static String[] ages = new String[] {
"30",
"30"
} mh_sh_highlight_all('java');
But can I not combine that into an array of objects? something along the lines of what you would do with json? like...
Java Code:
private static array[] multi = new array(){
{"name":"AIDANMACK","age":"30"},
{"name":"johnsmith","age":"31"}
} mh_sh_highlight_all('java');
For class, we need to create a word game using classes and objects.
The game is played in rounds. The player is presented with a word that is missing letters. The player has to fill in the missing spaces with their letter guesses. The words presented are chosen with a random number generator which has been provided for us. At the end of the game, the player is shown their score.
In steps, I have to:
-Welcome the player.
-Present the puzzle.
-Allow the player to fill in the blanks.
-Have the program check responses for correct/incorrect input.
-End the game if they have three misses, or continue if they complete the puzzle.
Now, to start, I have a class for the number generator, a class to store the array of 25 words, and a class for the game itself.
I'm really new to object/class concepts and already having difficulties with applying them. How to create and return an array of Exam objects? I need to get a data from a textfile which is passed to the method.
Java Code:
public Exam(String firstName, String lastName, int ID, String examType, int score) {
this.firstName = firstName;
this.lastName = lastName;
this.ID = ID;
this.examType = examType;
this.score = score;
[Code] ....
I'm really new to object/class concepts and already having difficulties with applying them. how to create and return an array of Exam objects? I need to get a data from a textfile which is passed to the method.
public Exam(String firstName, String lastName, int ID, String examType, int score)
{
this.firstName = firstName;
this.lastName = lastName;
this.ID = ID;
this.examType = examType;
this.score = score;
[code]....
I have this source code that is supposed to count the repeated occurrences of certain strings in the text file, "string.txt". The contents of the file are listed below:
AA-AB-AC-AG-AE-AL
AL-AQ-AE-AN-AO-AM
AM-AQ-AO-AA-AB-AC
AD-AJ-AK-AI-AM-AO
AN-AH-AC-AA-AP-AQ
AP-AP-AN-AN-AL-AP
AN-AD-AU-AE-AH-AQ
AK-AQ-AE-AL-AE-AA
AA-AJ-AB-AG-AE-AF
[code]....
Question: 1. Declare and implement a class named Substrings. The class will contain the following data members and methods:
Data members:
string S
Methods:
setS() take a string as a parameter and store it in S
printSub1(), printSub2(), printSub3(), printSub4() print all substrings of S. If S = "abcd",
printSub1() will print "a", "ab", "abc", "abcd", "b", "bc", "bcd", "c", "cd", "d",
printSub2() will print "abcd", "bcd", "cd", "d", "abc", "bc", "c", "ab", "b", "a",
printSub3() will print "a", "b", "c", "d", "ab", "bc", "cd", "abc", "bcd", "abcd", and
printSub4() will print "abcd", "abc", "bcd", "ab", "bc", "cd", "a", "b", "c", "d".
Alright so after doing some googling and watching tutorials I managed to put together the first two but I still don't exactly understand how nested for loops work, however just a single loop I do understand.
Secondly, the 3rd and 4th prints are completely destroying my brain using for loops, which we are supposed to use. Check out my code below, also keep in mind the 3rd is giving errors and the 4th i had to revert back to the same as the first print temporarily because my code because so messed up. How to understand nested for loops better.
[code=Java]
import java.util.Scanner;
class subString {
String S;
void setSubstring(String SS) {
S = SS;
[Code] .....
Compiling: error for myS.printSub3 and myS.printSub4 is the same as 1 because i had to revert it after ruining the code.
I'm attempting a small program as I'm teaching myself the ropes. In it, I need to compare one string (the base) to another which is just the base string that's had it's characters shuffled.
Java Code:
String base = "ABCDEFG"
String shuffled = "CDAFBEG" mh_sh_highlight_all('java');
What I need to do is run a loop that shuffles the base string each time, but compares and saves any characters that match in the correct location. For example, if shuffled = "CDAFBEG", then the G would be "locked" in place and the rest of the characters shuffled and looped back to the comparison.
I have all the code I need for shuffling the string, but I'm not sure how I would go about comparing each character and then also locking it in place. I get the basics, I think, of needed to use several variables.