I am using findbugs and PMD as a code analyser. I am keep getting warnings to use local variables and method parameters as final.
I want to know if its a good practice to keep them final or what to do?
Sometime i have a private method which is 1 line longer. Sometime it is annoying to use final.
you can also refer this link Local variables in java?Local variables in java?To meet temporary requirements of the programmers some times..we have to create variables inside method or bock or constructor such type of variables are called as Local Variables.
----> Local variables also known as stack variables or automatic variables or temporary variables
----> Local variables will be stored inside Stack.
-----> The local variables will be created while executing the block
in which we declared it and destroyed once the block completed. Hence the scope of local variables is exactly same as the block in which we declared it.
package com.javatask.in;
class A{
public static void main(String args[]){
int i=0; // Local variable
[code]....
Let's say I have a loop that loops through objects in an ArrayList then does stuff with them. Is it better for me to store the object in a temporary local variable and do stuff with it, or always use the ".get(arrayindex)" thing?
View Replies View RelatedBasically this code is supposed to create an int array of 50 elements, then pull the elements listed in positions 1-6 to make a lottery draw.
Problem is it gets down to that last "For" statement and then says "duplicate local variable i." If I attempt to separate it from the previous for loop with curly braces, then it gets mad and says it doesn't know what "local variable i" even IS. So I tried changing it to "j" in the last statement and it couldn't recognise that either. I feel like I need to change the variable name in that second for loop but I'm not sure how to make it understand that the second variable is going to be outputting the values from the first variable.
public class Lottery {
public static void main(String[] args) {
// TODO Auto-generated method stub
int []nums = new int [50];
for (int i = 1; i <50; i ++) {nums[i] = i;}
[Code] ....
I am unable to understand the meaning of this sentence "final reference variables must be initialized before the constructor completes.",What is trying to imply?
View Replies View Relatedwhy using the get method(c.get(c.HOUR_OF_DAY)); gives me the correct hour(currently 19) but directly accesing c.HOUR_OF_DAY returns 11 ? It shows In the documentation that HOUR_OF_DAY is public.
import java.util.*;
public class calendar2 {
public static void main(String[] args) {
new calendar2().timer();
}
private void timer() {
Calendar c=Calendar.getInstance();
//c.clear();
System.out.println(c.get(c.HOUR_OF_DAY));
System.out.println(c.HOUR_OF_DAY);
}
}
While reading head first java i encountered a problem(Pg. 90 chapter 4 - mixed messages).
Suppose in a class(say A) outside main() a counter variable is declared and initialized to 0.
In main() declared the array of objects of the class A.
Consider a while loop in which we increment the counter as follows:
public class A{
int counter = 0;
public static void main(String[] args){
A[] arr = new A[20];
int x = 0;
while(x<4){
arr[x] = new A(); //arr[] is array object
arr[x].counter += 1;
x++;
}
}
};
what is the final value of counter ? will it be the same for all array objects.
this is my program error occured run time,but compile sucessfully
{error msg-Error: Main method not found in class helloworldapp.HelloWorldApp, please define the main method as:
public static void main(String[] args)}
class HelloWorldApp
{
private int empno;
private float salary;
void setHelloWorldApp()
{
empno=12;
salary=1200;
[code]....
is it necessary that inner classes inside a static method be static . If yes Why?
View Replies View RelatedMy teacher has asked me one question that "What is difference between the final method and static method".
View Replies View RelatedJava-code, When i compile the java doc. I get output;
Perceptron.java:12: learn(Instance[],int,int) in Perceptron cannot be applied to (Instance[],int)
PerceptronModel model = learn(train_data,5);
^
1 error
And here is the code
import java.io.*;
public class Perceptron {
public static void main(String[] args) throws IOException {
DataReader reader = new DataReader();
reader.init(args);
[Code] ....
1 Can method declared as final be overridden and overloading ?
2 if A is static sub class of B. how to access a method in class A ?
this code won't compile because selected row must be declared as final because of it being defined outside the window listener. Is their anyway around this? If I make it final the first time that the variable is called it keeps it starting value until the GUI is closed.
butEdit.addActionListener (new ActionListener () {
@Override
public void actionPerformed (java.awt.event.ActionEvent evt) {
int selectedRow = table.getSelectedRow ();
final String [] values = custTableModel.getRowValues (selectedRow);
[code]....
class A
{
public final int Add(int a,int b) {
return a+b;
}
}
class B
{
public static void main (String args[])
{
System.out.println(Model.Add(5,10));
}
}
This is what I have. I'm not sure if this even makes use of a final method. But when I run it I get an error saying cannot find symbol for line 13.
Created a java.sql.connection object. Refering those obj inside public void run() { } If i declare as final inside a method, i can't refer those outside method due to scope. Cannot refer to a non-final variable dbConnObj inside an inner class defined in a different method...
View Replies View RelatedI want to create a final array with final elements
{code}
final int[] array = {0, 1, 2, 3, 4, 5};
{code}
But here only the reference of the array is final , not it's elements ... So how can I do that??
I am trying to write a simple test case for one of my web service.The main method
return object :: offersService
MainClass
public OffersService getOffers(String input1, Map input2) {
// userId, Password loaded from another properties files
String response = validateUser(String userId, String Password)
[code]...
This code had no bug until I wrote down a call to a method signin with two parameters name and password. I need to know where exactly do I write down the deifintion of this method public void signin(String name, String password).
I have tried writing this several times and each times I get an annoying syntax error asking for more curly or round brackets.. There is only one error it shows after declaring this method . So I know that I am not writing it in the correct place, Do I keep it inside the action listener or outside. Everywhere am getting error. I want to be able to call methods and define them as I was doing in Bluej all this while.
import java.awt.EventQueue;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import java.awt.Font;
import javax.swing.JButton;
[Code] ....
I've just been having a go at an exercise where I have to create and use a class called Point, with two fields of type double. I have to create some methods for it, one of which is a distanceTo(Point) method, that calculates the distance to another point. I've tried to keep the distanceTo(Point) method short so have created some other methods to use within the method. My question is about the getDistance() method that I've made. As you can see below, I've given it two parameters, which are references to values within two Point objects (this.x and otherPoint.x).
double distanceTo(Point otherPoint) {
double distanceX = getDistance(this.x, otherPoint.x);
double distanceY = getDistance(this.y, otherPoint.y);
return calculateLength(distanceX, distanceY);
}
Create a method called mirrorImage, which takes two integer arrays as input parameters. You may assume that the two actual parameters have the same length. Your method should return true if the arrays are the reverse of each other. Otherwise mirrorImage should return false.
Examples:
data1:{1,2,3}
data2:{3,2,1}
==> true
[code].....
I'm pointing a place outside of the array or something
runtime error (line 8, column 0): java.lang.ArrayIndexOutOfBoundsException: 10
-> array.ArrayQuestions.mirrorImage()
Now that I have figured out how to return a single variable from a method I am on to the next step, I need to return 2 or 3 variables from a method. I have searched the internet on how to do this to no avail (am I doing the wrong search? I do not know) but what I need to do is return a second (and eventually a third variable)
Here is what I have
private static String Engine() {
String engine = "";
int enginePrice = 0;
System.out.println("Choose a engine size:");
System.out.println("[4] cylinder");
[Code] .....
Which does not work.
Can method variables be shared between users?
I was asked this on an interview and I didn't know what to make of it.
I'm taking a class in object oriented programming and we have a task to write a method that returns positive, negative or zero depending on the sum of two variables.
I've had a go at it and i've got to a certain point but i'm struggling to get past this on error - return outside method.
public class Test {
public int sumArgs;
public int arg1;
public int arg2;
[Code] ....
The error occurs on the line 'return "Positive";
a. Create an application named ArithmeticMethods whose main() method holds two integer variables. Assign values to the variables. In turn, pass each value to methods named displayNumberPlus10(), displayNumberPlus100(), and displayNumberPlus1000(). Create each method to perform the task its name implies.
b. Modify the ArithmeticMethods class to accept the values of the two integers from a user at the keyboard.
I used the string split method in the following lines of code like this:
String[] numbers = out.split("[^d.]", 0);
String[] operations = out.split("[.d()]", 0);
When out is equal to the String "2x2.5", the array operations ends up looking like this when it is printed using the toString method:
[, , , x]
As you can see, before the array element x, there are three String variables which only contain whitespace. Why does this occur, and how can I prevent this from happening?
I am very Java illiterate and I need to know how would i set all the variables in the first class to null or 0 to make a new method to clear everything.
import java.util.Arrays;
import java.util.Scanner;
public class studentMethods
{
private double totalScore;
private int count;
[Code] ....