Netbeans tells me it's an illegal start of expression during the initialisation of the interactWithUser method.
public class InvertLetter {
/**
* @param args the command line arguments
*/
public static void main(String[] args) {
/**
* String mit den Kleinbuchstaben.
*/
final String lowercase = "abcdefghijklmnopqrstuvwxyz";
[Code] ....
import java.util.HashSet;
import java.util.ArrayList;
public class Graph
{
double [] [] adj;
graph (double [] [] a)
{
adj= new double [a.length][a.length];
for (int i=0;i<a.length;i++)
for (int j=0;j<a.length;j++)
adj[i][j]=a[i][j];
}
C:UserscDesktopGraph.java:: error: invalid method declaration; return type required
graph (double [] [] a)
I have one interface with three(more than one) method declaration. In the subclass that implements it I want to define only one method not all three not even blank definition of them.Is there any keyword or method for that. How to do it? Is it possible to do it? In GUI we use adapter classes to achieve it. What for console application?
View Replies View Relatedimport java.util.Scanner;
public class days
{ public EnumTest ()
{ this.day = weeks/months/years}
final int daysInMonth = 30; //constants
final int monthsInYear = 12;
final int daysInWeek = 7;
public void convert()
[Code] ....
after compiling it shows invalid method declaration ; return type required.
Create an array that will store 7 temperatures.
Populate the array with 7 random temperatures from 1 to 100 degrees. (hint use a for loop and a Random number Generator)After the temperatures are in the array, calculate the average of the temperatures in the array.
Print out the average.Print out each temperature in a statement comparing it to the average such as:
The average temperature is 48.94
Temperature 1 is 5.0 and is below average.
Temperature 2 is 67.8 and is above average.
import java.util.Random;
public class ArrayOfTemperatures
{
public static void main(String[] args) {
// Declare an array
int[] randomtemps = new int[7];
temps[0] = 45;
[code]....
I saw an example where an (inner)class is declared inside the main method, this is correct or not and why/when it's reasonable to use?so smth like this
public class myClass()
{
public static void myMethod(myInnerClass obj)
{
if (obj.method())
[code]....
Why is the logic not correct with the method public static boolean containsColor(String color, Circle [] ca)? It only returns me only false values.
Java Code: public class Circle {
private double radius;
private String color;
public Circle()
{
radius = 1;
color = "red";
[code]....
Let's say within a class I create a method that takes care of creating a java swing layout with labels, buttons etc.. then attach an action listener (inner class) for each button to change a respective label text. All I would need is that the action listener method can access and modify the label as needed.
Have read about static, protected, private, getters and setters but honestly bit confused about which structure should be adopted as a best practice. Global static protected variables for the labels along with private inner classes implementing ActionListeners believe will do the trick and will be able to access the labels but not convinced this is good practice.
My Question is Suppose I am declaring an String array as
String[] a
or
String a[]
or
Comparable[] a
Will there be any performance or other advantage or disadvantage using these syntax?
I tried this:
String[][]f = new String[1][1] {{"Harry"}{"Hairy"}};
I also tried this:
String[][]f = new String[1][1] {{"Harry"},{"Hairy"}};
but I get an error
Ok say you have
public class MyClass {
private int x = 5;
Object myObject = new Object();
public MyClass(){
}
}
When would the myObject be created? Before or after the constructor? And does this mean you can't pass
this into the parameters of that object?
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.
[Code] ....
I started learning JSTL (Java Standard Tag Library) and i got to know that i need to mention this directive in JSP page
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
in order to use JSTL tags.
I am not able to understand what does this URI exists at all ?? I feel it making things complex and meaningless or else i am missing something hidden and secret.
Whilst pre-preparing for java certification, one of the online mock exams has slightly confused me by saying my answer was incorrect for multi-dimension array 'declaration and instantiation'.
This is one of the answers i chose - which was marked as incorrect
a)
int[][] array2d = {{123}, {4,5}};
Which looks absolutely fine to me.One of the other answers, which i agree is correct and so does the mock exam is
b)
int [][] array2d = new int[2][2];
when a new object is created in Java it follows the idiom:
Object obj = new Object();
where the Object() constructor matches the object type Object.
But what if it doesn't? I understand from the Oracle Docs on creating objects and polymorphism that the constructor must be in that object's class or one of its subclasses. However, suppose we wanted to declare a new stack. My first instinct would be:
Stack s1 = new Stack();
But I assume it's valid to do it this way, too:
Object s2 = new Stack(); // Is there a difference here? What are we really saying about s2? I'm guessing s2 is simply an empty stack, but only has access to the Object class methods? I'm not sure why someone would ever do this, but I want to solidify my understanding of the Java hierarchy. Are there really any circumstances where someone would use a subclass's constructor when creating a new object?
I have doubts in string declaration. As I know we can declare string in two ways:
1. String a=new String("Hello");
2. String b="Hello";
What is exact difference between them? Another thing is when I check (a==b) it retuns me false, but when I check a.equals(b) it returns me with true. Why So?
I know that I can declare and initialize an member variable inside a class in a single statement but I can't do them on separate sentence. Why?
For example, I am allowed to do the following,
class A{
int a = 5;
// rest of the class
}
But I am not allowed to do this,
class A{
int a;
a = 5; // it doesn't compile even when the variable 'a' is static
// rest of the class
}
Why java don't allow me to do that?
I have an application that uses an object that is declared globally for the class. Within a method that is triggered by a user event, it creates a new object and assigns it to this global object declaration. My question is, when the object is overwritten multiple times by the user selecting the button that calls this method, will the older instances be garbage collected or is there still a reference to them? Is there any downfall to this logic and if so what would be a solution.
View Replies View RelatedI have to implement all the stack methods in java such as push, pop empty, not using the ready methods but have to create them and to execute an exercise but is sth wrong with it
public class Stiva {
/** the problem is here how to declare the stack 1 and stack 2 and kreu(head) gjmax(size)*/
int Gjmax;
int array[] = new int[Gjmax];
int kreu;
private Stiva stiva1;
private Stiva stiva2;
[Code] .....
How to write a program which will automatically correct the parts of speech of a document.
Example: say in my document I have My/PRONOUN name/PRONOUN is/VERB Jhon/NOUN. He/PRONOUN is/VERB going/ADJ to/PREPOSITION school/NOUN
Now I need to change My/PRONOUN name/NOUN is/VERB Jhon/NOUN. He/PRONOUN is/VERB going/VERB to/PREPOSITION school/NOUN...How to do using java. The document may contain 100 lines tagged with parts of speech.
I have a simple WORKING Factorial program code but I don't understand how it works.Here is code snippet
public class Factorial{
public static void main(String[] args){
long limit = 5;
//long factorial = 1;
[code]....
My question is - every time in a given FOR loop if Factorial value (highlighted and bold above) is initialized / reset to "long factorial = 1" then how does code produces correct values? Because correct values can be produced only if interim factorial results are saved/stored and used next time to multiply with "factor" value.
Here instead of retaining it, we initialize or reset to 1 so every time you multiply by 1 and it should produce 1! = 1, 2! = 2, 3! = 3, 4! = 4 etc which would be an incorrect result.
I want to use the bit of code below to re-write the page to tell the user of a successful registration and then redirect them to another page. My problem is that I can't figure out how to get the path right for the login page. As can see, my first choice was to have the use click to the login page and when I use href it works fine.
I tried to use the entire file page starting at C and that didn't work. I also tried
${pageContext.request.contextPath}/Login
which is what I had to do for the action in the form for the login servlet page.
My question is what is the URL I need to use. By the way, if I jut put in google's URL, or any other for that matter, it works fine.
out.println(docType +
"<html>
" +
"<head><title>" + "Already Registered" + "</title>" +
"<meta http-equiv='refresh' content='3; URL='Login.jsp'></head>
[Code] .....
I'm trying to figure out the correct way to replace number into letter. In this case, I need two steps.
First, convert letter to number. Second, restore number to word.
Words list: a = 1, b = 2, f = 6 and k = 11.
I have word: "baafk"
So, for first step, it must be: "211611"
Number "211611" must be converted to "baafk".
But, I failed at second step.
Code I've tried:
public class str_number {
public static void main(String[] args){
String word = "baafk";
String number = word.replace("a", "1").replace("b","2").replace("f","6").replace("k","11");
System.out.println(word);
[Code] .....
Result for converting to number: baafk = 211611 But, result for converting above number to letter: 211611 = bkfk
What do I miss here?
How to distinguish if 11 is for "aa" and for "k"? D
I'm having extreme troubles with my outputs not displaying the correct math. I have everything organized how I want it, it's just not giving me the correct answers.
The code is supposed prompt the user to enter an investment amount and an interest rate and display the future investment amount for years 1-30. The formula for this is:
futureInvestmentAmount = investmentAmount * (1 + monthlyInterestRate)^(numberOfYears*12)
Here is my code:
import java.util.Scanner;
public class InvestmentValue {
public static void main(String[] args) {
// prompt user to enter data
Scanner scan = new Scanner(System.in);
System.out.println("The amount invested: ");
[Code] ....
And I have to use a method to do this as it is what we are learning in class right now. A sample output as of now is:
The amount invested:
1000
Annual interest rate:
9
Years Future Value
11.0E15
21.0E27
[Code] .....
And obviously a future investment amount cannot equal infinity.
This first number of the output is meant to be a timestamp for the data (formatted to show only minutes). The second part of data, after the ':', is the data being read from the serialport. This number is not correct, and is changed within this bit of code. The data is read as "Solar: A.AA", where A.AA is a number read from a sensor. I am able to read the data fine right before this if statement, but after that the data output changes. StringProperty is not printing out the correct data:
Java Code:
serialPort.addEventListener(event -> {
if(event.isRXCHAR()) {
try {
sb = new StringBuilder();
sb.append(serialPort.readString(event.getEventValue()));
String str = sb.toString();
if(str.endsWith("
[code]....
I need to force the user to enter an integer between 1 an 11. The code below works great.... It will work fine if the user inputs any letter or character and reprompt for a number. However once a number is entered(a number out of range-or it would just accept the number) and then the user enters a letter or character that isnt an int the program crashes with a input mismatch exception. I see WHY it is doing this but I cant figure out how to put my while loops to fix this! Here is the code. Someone suggested to Catch the exceptions, then prompt for retry if I encounter one.. however I havn't used the try - catch for exception handling before. Here is my code.
public static int getDecadeSelection() {
int decadeChoice = 0;
System.out.println( "
Choose your decade: " );
System.out.println( " 1 - 1900-1909 " );
System.out.println( " 2 - 1910-1919" );
System.out.println( " 3 - 1920-1929" );
System.out.println( " 4 - 1930-1939" );
System.out.println( " 5 - 1940-1949" );
[Code] ....
It is because I am setting decadeChoice to console.nextInt, so once it passes that if the user inputs a letter it will crash, just not sure how to make it work.