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I guess you are reading someone else's bad code. Java of itself is a fine language for solving many problems. But like any language it can easily be misused.
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How to replace particular numbers in the series of prime numbers generated with a letter in java?
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how to execute java class file in ms-dos. what are tool to use execute java class file in windows os
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Assuming you actually mean in a command prompt window then it is just a matter of running it via the java command.
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class Sort1
{
public static void main(String...avg)
{
int a[][]={{10,50,40},{15,25,10},{25,14,19}};
for(int i=0;i<a.length;i++)
{
for(int j = 0;j<a[i].length;j++)
{
System.out.print(a[i][j]+"\t");
}
System.out.println();
}
int l =a.length;
int b[]=new int[l];
int c=0;
for(int k=0;k<a.length;k++)
{
for(int m=0;m<a[k].length;k++)
{
b[c]=a[k][m];
System.out.print(b[c] +"\t");
c++;
}
}
}
}
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yeah, i want to know how to calculate the length of 2d array while converting it into 1d array
when i simply used a.length for my 2d array and put it into my 1d array ,then 1d array will print only first column then exception comes Array index out of bound
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Well I would guess it is the total number of elements in your 2D array. So it is just a question of adding the number of elements in array[0] + array[1] + ...
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yup i got the idea and it works like this
int a[][]={{1,2,3},{4,5,6},{7,2,6}};
int b[] = new int[a.length*a.length];
System.out.print(b.length);
//output is 9
//is this the way of getting length of 2d into 1d array?
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What happens if you have something like:
int a[][]={{1,2,3,7,12},{4,5},{7,2,6,9,9,11,22,33,44,55}};
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yup in that case my logic isn't working
if you can, please tell me the universal logic for calculating the length while converting 2d array into 1d array
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ok i got the answer
thanks buddy for help 
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This is showing error
So i solved from my self.....
class Sort1{
public static void main(String...avg)
{
int a[][]={{10,50,40},{15,25,10},{25,14,19}};
int l =a.length;
int b[]=new int[9];
int x=0;
for(int i=0;i<a.length;i++)
{
for(int j = 0;j<a[i].length;j++)
{
System.out.print(a[i][j]+"\t");
b[x]=a[i][j];
x++;
}
System.out.println();
for(int k=0;k<b.length;k++)
{
System.out.print(b[k] +"\t");
}
}
}
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Basically i was trying to do bubble sorting in 2d array with logic
first converted 2d array into 1 d array then sort the elements and again converted back that array into 2d array
class Sort1
{
public static void main(String...avg)
{
int a[][]={{1,2,3,7,12},{4,5},{7,2,6,9,9,11,22,33,44,55}};
//System.out.print(a.length);
int totalelements=0;
for(int x=0;x<a.length;x++)
{
for(int y=0;y<a[x].length;y++)
{
totalelements++;
}
}
//System.out.print(totalelements);
System.out.println("\n"+"unsorted 2d array"+"\n");
for(int i=0;i<a.length;i++)
{
for(int j=0;j<a[i].length;j++)
{
System.out.print(a[i][j]+"\t");
}
System.out.println();
}
System.out.println("\n"+"converted 2d array into 1d array"+"\n");
int b[]=new int[totalelements];
//System.out.print(b.length);
int l=b.length;
int c=0;
for(int k=0;k<a.length;k++)
{
for(int m=0;m<a[k].length;m++)
{
b[c]=a[k][m];
System.out.print(b[c] +"\t");
c++;
}
}
for( int i =1; i<=l-1;i++)
{
for(int j=0; j<l-i;j++)
{
if(b[j]>b[j+1])
{
c =b[j];
b[j]=b[j+1];
b[j+1]=c;
}
}
}
int n=0;
for(int i=0 ; i<a.length ; i++)
{
for(int j=0 ; j<a[i].length ; j++)
{
a[i][j] = b[n];
n++;
}
}
System.out.println("\n"+"\n"+"Sorted 2d array "+"\n");
for(int i=0 ; i<a.length ; i++)
{
for(int j=0 ; j<a[i].length ; j++)
{
System.out.print(a[i][j]+" ");
}
System.out.println();
}
}
}
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Hi!
I am currently coding in JSF, but using Java for the back-end beans. Was wondering if anyone is familiar to JSF, to help get a solution or an idea on how I could proceed.
So, if I have a database with 2 tables - Country & State,
but I don't want to have to make a call into the database in order to reduce the resources used. How would I implement in the Java bean a connection between the country and its related states?
Considering that I have the 2 selections in a dropdown menu.
Thanks!
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If you do not want to use the database then you need to hold all the data in Lists inside the code, which may be just as expensive.
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And if I make a call to the database, then I'm probably looking to use a couple of for-loops
to go through both tables in my back bean?
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Yes, probably. It's a trade off, whichever method you use will have a cost. You need to decide which is the better option for your application.
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a very beginner question...
i'm a newbie in programming... just started java and read about packaging... i created i directory called firstproject and put a directory with one class inside of it and a FirstProject source file in the firstproject directory itself.
i made a class in that package directory that has a private string in it and tried to invoke from FirstProject source file but
getting compile error that the string is private...
i tried changing the string into protected or even public but still getting this error...
this is the class src file...
<pre lang="java">
package stickers;
public class Sticker
{
private String note;
Sticker(String note)
{
this.note = note;
}
public void displayNote()
{
System.out.println(note);
}
}
this is the FirstProject src file...
package firstproject;
import stickers.Sticker;
public class FirstProject
{
public static void main(String[] args)
{
Sticker sticker = new Sticker("hello sticky mehdi");
sticker.displayNote();
}
}
this is the actuall error:
error: Sticker(String) is not public in Sticker; cannot be accessed from outside package
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You need to make your constructor public so other packages can access it:
public class Sticker
{
private String note;
public Sticker(String note)
{
this.note = note;
}
I would recommend going to The Java Tutorials[^] and working through them.
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Hello there. I have managed to load and use c++ dll using JNI, in my java servlet (System.load). It works perfectly on first request I submit. But on subsequent requests, I get this weir d exception.
java.lang.UnsatisfiedLinkError: Native Library WEB-INF/lib/XXXXXX.dll already loaded in another classloader<br />
at java.lang.ClassLoader.loadLibrary0(ClassLoader.java:1525)
Here is my loading code
public void init(ServletConfig config) throws ServletException
{
super.init(config);
ServletContext context = getServletContext();
String sMathDllpath = context.getInitParameter("MathDLLPath");
System.load(sMathDllpath);
}
I studied this tomcat wiki link and implemented their solution, among others, but could not succeed.
How do I implement it successfully? Thnks for anything you share.
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You should declare it as a static action at class level like:
class ... {
static
{
System.loadLibrary("MathDLLPath");
}
}
That will ensure it is loaded when the class is first instantiated, but will only be loaded once.
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Richard MacCutchan wrote: You should declare it as a static action at class level like:
I tried this just now. This is what I have
public class MainServlet extends HttpServlet
{
static{
System.loadLibrary("MathDll");
}
.........
}
And this is the exception I am getting
<br />
java.lang.UnsatisfiedLinkError: Native Library C:\Program Files\Java\jdk1.7.0_71\bin\MathDll.dll already loaded in another classloader<br />
What am I doing wrong now?
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