Question concerning LinkedList of int arrays
This is probably a stupid question, but...
The following section of code is intended to examine the vertices of a graph, set the value of nMatrix[j][k] to 0 whenever there is no edge connecting vertices j and k, and place an int array {j,k} into a LinkedList setN whenever an edge does connect vertices j and k.
/*g is the graph, getV() returns the array of vertices*/
int[][] nMatrix = new int[g.getV().length][g.getV().length];
/*set N*/ LinkedList setN = new LinkedList();
for (int j = 0; j < g.getV().length; j++) {
for (int k = 0; k < g.getV().length; k++) {
if (g.getV()[j].hasNeighbor(g.getV()[k]))
/*place the n_jk in set N*/
setN.add(new int[] {j,k});
else nMatrix[j][k] = 0;
}The code does what it's supposed to do as far as I can tell, but my question is: How do I retrieve the arrays in setN as int[]'s rather than instances of the Object class? For a moment I thought I could use
Integer[] n = (Integer[])setN.get(index);to retrieve the array, but that returned a run-time error. Can anyone out there provide some input?
I can now retrieve arrays from my LinkedList without any problems, but when I try to find an array within that LinkedList using the indexOf() method, it always returns -1.
My code:
static boolean solvable (Graph g) {
Vertex[] v = g.getV();
int[] c = g.getC();
int[] d = g.getD();
int c_sum = sum(c);
int d_sum = sum(d);
/* snip */
LinkedList setN = new LinkedList();
//here's where I add arrays to set N
for (int h = 0; h < v.length; h++) {
for (int j = 0; j < v.length; j++) {
if (v[h].hasNeighbor(v[j])) {
setN.add(new int[] {h,j});
/*each array of size 2 in setN corresponds to a certain int value; this array contains those values*/
int[] setN_vals = new int[setN.size()];
for (int j = 0; j < setN_vals.length; j++) {
setN_vals[j] = 0;
/*snip*/
//This next function takes the LinkedList setN as an argument. It is called within the body of solvable().
static boolean Watsons(int k, int m, LinkedList setN, int[] vals, int cmd) {
int total = 0;
for (int l = 0; l < m; l++) {
int n_index = setN.indexOf(/*(Object)*/new int[] {k,l}); /*this always returns -1, even if the array {k,l} had earlier been placed in setN*/
if (n_index > -1)
total += 2 * vals[n_index];
/* snip */
}I've tried it with and without the (Object) coercion tag, but it doesn't seem to be able to find the array either way.
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Hi All,
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int iArr[] = {5,3,7};
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how to proceed?
ThanksHi "mkreddy123",
If I understand you correctly, you want to sort an 'int' array in descending order.
If this is correct, then I suggest using the "sort()" method in class "java.util.Arrays".
I didn't see any mention (in your post) of the java version you are using, so I will assume you are using the latest version (1.4). Here is a link to the relevant javadoc:
http://java.sun.com/j2se/1.4.1/docs/api/java/util/Arrays.html
Of-course that sorts the array in ascending order. You then need to "reverse" the array in order to get descending order.
[I'm assuming you _do_ know how to reverse an array -- in other words, make the last element in the array, the first element; make the second last element in the array the second element; and so on.]
Hope this helps.
Good Luck,
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Returning int array from C to Java as method parameter
Hello,
I've been trying to accomplish this
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int[] myArray = ... (filled with some data);
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JNIEXPORT jint JNICALL Java_GenChav_rsaEncrypt(JNIEnv *env, jobject obj, jintArray myArray){
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I tought this way I would have a updated myArray ints on the Java program...
Any thought??user5945780 wrote:
Ok, let's try to be constructive here...
How I do implement a return type for my method like a int array ?First realized it has nothing to do with JNI. So the same question and answer applies to java only.
>
like:
int[] return = myNativeCall();
Yes.
Then I will look for return[0], if it is == to 0, fine, it means a successful calculation by the native code. Not sure what that means. The structure of what you return it up to you.
It can help when you are unsure of what to do in JNI....write a pseudo representation of what you want to do in a java method. Then translate that java method into JNI, everything in the pseudo method must be in the JNI code. -
How to convert an int array to string array?
Hi,
Can anyone please help me with this question?
int number={4,6,45,3,2,77};
I like to convert this into a list and sort
List mylist = Arrays.asList(number);
Collections.sort(mylist);
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Please advise. Thanks.If you want to convert your int array to a String array, you have no choice but doing a conversion element by element in a for loop.
However, if the sort method doesn't behave as desired, you can use the one with 2 parameters, the second parameter being a comparator class.
Check the javadoc for more information : http://java.sun.com/j2se/1.3/docs/api/java/util/Collections.html
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I recently completed my first Comp Sci. class in Java and have decided to try to continue learning on my own. I am now trying to make a pong game, using a turorial. Unforunately my course did not cover threads in any way, shape, or form. I am able to get the beginning of the program to work (code posted below) and have no problems with it; however, I do have a few questions concerning what certain elements of the code do.
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2. In my program there are two lines (32 & 79) where the thread priority is changed. Can someone explain what that means and how it affects my applet?
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}Thanks for any help, it is greatly appreciated.Questie,
Please control yourself. Please.??
As the program runs it is one thread. (You canthink
of each thread as an independent program if youlike.
This is not 100% accurate but close enough that
it
might help you understand)
It will only confuse the OP
You are a flat out wrong for a number of reasons.
1) You seemed to miss the part where I did say that a
doubling in peformance is fictious and is dependent
on a number of factors.As i was telling that would only confuse the OP.Its better to be 100% precise when you explain to an OP
2) You don't understand how a multi-process OS works
in the least.Assumptions as usual
3) You don't understand how processors work in the
least.Well,what was i saying?
2 and 3 are important because your point about
context switching is not valid. First of all because
this happens anyway because your program is not the
only thing running the processor. Second because of
the first point each thread gets a timeslice, you may
with multiple threads each get a timeslice and these
slices may (and often do) add up to more total time
then the first got by itself.When you consider a solution to a problem the average and the worst case has more weightage than the best case.You are taking the best case assumption here-"because ofthe first point each thread
gets a timeslice, you may with multiple threads each
get a timeslice and these slices may (and often do)
add up to more total time then the first got by itself".Now dont stop whining that you werent.Never take the best case always coz its the average and worst case which checks if the system festers to a condition beyond rectification
For example (these numbers are fictional but I am
trying to explain it so don't go off all half-cocked
again please)
Program with one thread. Each thread gets 100 cycles
per second.
Program with four threads. Each thread gets 50 cycles
per second.
The second program will finish in half the time as
the first. Because even though each thread is slower
as a whole the program is getting twice the cycles
of the processor as before. You are taking the best case again and moreover its the cpu scheduling algo which decides the time slice and not you sitting on the CPU.I have a vague feeling that you have an idea that you are sitting on the CPU deciding the Time Slice.
You need to understand something important here. Alot
of the time when you are doing things in a program,
and this doesn't just apply to IO here, you don't
have to use the processor for each step. There is
some shifting around of things to get them ready to
be executed by the processor. A more advanced
representation of this is to be found with
Hyperthreading. Hyperthreading processors (single
core) are of course single core but they act as if
they were multi-core (multi processes) because while
only one process is actually executing at one time
the others are pipelined in such a way to make sure
that the executing core of the processor has the
least amount of idle time possible.Digression
So that means on a basic processor each time you add
2 numbers it takes 5 steps. And the processor core is
idle 80% of the time.
From where did you get that 80%?Stop coming up with your own numberes.This is no number game
So for example while some data is being placed in the
outbox new data is also being collected and is at
step 2 already. In this model while we are still on a
single core the core is now idle only 60% of the time[b]From where did you get 60% now
So yes threading is very useful for IO and other
operations that may block your program but they have
more use than just that. Parallel execution can and
will have some performance advantages (if designed
properly) even on a single core processor without
hyperthreading. In a well written multithreaded
program when you add hyperthreading and multiple
cores or multiple processors to the mix then you
really have something.I never said it wont.Read properly what i have posted.I told dont take the best case always.You need to consider that too but the other two carries more weightage
Please don't feel you ever have to post to correct me
again thanks.^^
Get ride of this self conceited attitude.Even if you have it dont make it public.Its not that you are always right cotton.I am not saying that you are wrong.If you have read my first reply i mentioned that i knew that you gave that example just to make the OP understand.The problem with that is that if the OP is unable to fathom out what you mean he is going to misconstrue whatever you have said and that propogates -
How do you invoke a method with native int array argument?
Hi,
Will someone help me to show me a few codes samples on how to invoke a method which has only one argument, an int [] array.
For exampe:
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Here is some simple code fragment I used:
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JeffSorry, my bad. I was able to invoke static methods and instance methods with all data types except native int, short, double and float, not sure the proper ways to declare them.
After many frustrating hours, I posted the message for help, but at that time, my mind was so numb that I created a faulted example because I cut and pasted the static method invocation example to test the instance method passing int array argument.
As your post suggested, "args[0] = intArray;", that works. Thanks!
You know, I did tried passing the argument like that first, but because I was not declaring the type properly, I ended up messing up the actual passing as well as the instantiation step.
I will honestly slap my hand three times.
jml -
The project I was assigned is to write a program that takes numbers from a text file (all on one line, separated by spaces) and store them into a 5-element array. The program is supposed to check and see if the array is big enough to hold all the numbers from the text file, and if it isn't, it is supposed to double that array size. I've written the following code and it compiles, but it will not run due to this error:
Exception in thread "main" java.lang.NullPointerException
at java.io.Reader.<init>(Reader.java:61)
at java.io.InputStreamReader.<init>(InputStreamReader.java:55)
at ArrayReader.main(ArrayReader.java:16)
----jGRASP wedge2: exit code for process is 1.
----jGRASP: operation complete.
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for (i = 0; i < array.length; i++)
System.out.println(array[i]);ursusmajx wrote:
Exception in thread "main" java.lang.NullPointerException
at java.io.Reader.<init>(Reader.java:61)
at java.io.InputStreamReader.<init>(InputStreamReader.java:55)
at ArrayReader.main(ArrayReader.java:16)Start by looking at line 16 in ArrayReader.main. It's not lie 16 in the code you posted here, so either you haven't posted the code you tried to run or you're not running the code you think you are.
I do see where you are using fis before assigning it a value.
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Message Edited by Schwenker on 11-23-2008 08:23 AMHello,
I would recommend Acronis to do this job. Here is a link at thinkpad-forum.de.
You´ll get Acronis for free if you buy a PCWelt.
Your answers:
A. yes
B: yes
C: yes
D: yes
E: No, windows is needed and if it´s XP than MS NET 2.0 also.
F: yes, when windows 7 is out, than Thinkvantage will work then, on Server 2008 it seems to work.
G:Thinkvantage work in Vista and XP environment.
H: yes, you can backup it on a extern hdd and later recover the R&R Image to the internal disc.
What do I want to achieve?
I would recommend Acronis to do this job. Here is a link at thinkpad-forum.de.
You´ll get Acronis for free, if you buy a PCWelt.
here are some interesting benchmark with first versions of Windows 7 and XP.
Windows 7 unmasked
Perceptions becomes reality
Message Edited by Agotthelf on 23-11-2008 10:23 PM
Follow @LenovoForums on Twitter! Try the forum search, before first posting: Forum Search Option
Please insert your type, model (not S/N) number and used OS in your posts.
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TIP: If your computer runs satisfactorily now, it may not be necessary to update the system.
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How to pass int array as an IN parameter to PLSQL Procedure
Hi,
How to pass int array in java to a stored procedure througn jdbc
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SHOW ERRORS
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7876 ADAMS 23-MAY-87
7934 MILLER 23-JAN-82 -
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Message was edited by:
maxfarrarYou can do a two-dimensional ArrayList? That syntax
you wrote didn't work.
I tried doing:
private ArrayList<ArrayList><Integer>> map;
Your syntax is just wrong -- or, this forum software has bug in handling angle brackets.
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