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Java program won't finish method - exits after a for loop with no errors instead

edit: As I was writing this post, I made my code simpler (lost arrays entirely) and got it working. Yet I am still not sure why this specific code won't work, so I'll keep the question.
Hello.
I am writing a small puzzle game in Java (using Eclipse 4.4.2) and stumbled upon a problem inside one of my methods. Basically - it won't complete the method, it just exits the method after the for loop is done without any warnings or errors (I'm not catching exceptions either). I hope I missed something simple..
Details:
I have a method to set the colors of an object and up to 5 other objects that are linked to it through lines. I set up the color of the main object, then find the linked objects through for-loops and in the end change their colors as well. (Double checked the code for Lines, there are simple return methods and nestA and nestB as data - no problem there). lines is an array with a length of 50, nests as its members.
Here's the code:
public void highlightNests(Nest nest) {
//setting the color of the main object (a nest).
Mappers.setColor(nest, nestHighlight);
//resetting the array. Temp solution, had a return method earlier,
//this is part of the debugging.
connectedNests = null;
connectedNests = new Nest[5];
int i = 0;
Gdx.app.log("highlightNests()", "starting the loop");
for (int j=0; j<lines.length; j++) {
if (lines[j].getNestA() == nest) {
connectedNests[i] = lines[j].getNestB();
i++;
}
if (lines[j].getNestB() == nest) {
connectedNests[i] = lines[j].getNestA();
i++;
}
}
//This is where the program exits the method. The following
//lines are not run.
Gdx.app.log("highlightNests()", "entering loop");
for (int l=0; i<connectedNests.length; l++) {
Mappers.setColor(connectedNests[l], nestHighlight);
Gdx.app.log("highlightNests", "set color");
}
}
Deleting the middle section makes the end part run, so there are no errors in the last part.

Your second loop is completely wrong, you declare the counter as l and increment another counter i, you should use l<connectedNests.length change it like this:
for (int l=0; l<connectedNests.length; l++) {
Mappers.setColor(connectedNests[l], nestHighlight);
Gdx.app.log("highlightNests", "set color");
}
And the program won't finish method and exits before the loop because, it doesn't even enter the loop as it's incorrect.

You have to use l instead of i in condition like,
for (int l=0; l<connectedNests.length; l++)...
//---------^ l not i

Jump values in loop "for"

I have two "for" loops.
for(n=0;n<6;n++){
for(w=n;w<6;w++){
// if w==4 then go to first loop an continue from n=4!!
}
}
How can i jump to n=4 when w takes value 4; Like old Basic command "goto"..
Thanks

How can i jump to n=4 when w takes value 4; Like old Basic command
"goto"
You can use break to "jump" out of the current loop back to the outer loop:
for(n=0;n<6;n++){
// other code
for(w=n;w<6;w++){
// if w==4 then go to first loop an continue from n=4!!
if (w == 4) {
n = 4;
break;
}
}
// other code
}

Printing to Console Does Nothing in For Loops

I've tried several programs that involve printing to the console in for loops, but none of them have printed anything. I can't work out the problem, and I've boiled it down as simply as possible here:
for (int x=0; x==10; x++)
{
System.out.print("Test");
}
Like I said, absolutely nothing is printed to the console. Things outside of the for loop will print, and things affected by the for loop will print.
Perhaps it's something very simple, but I wouldn't know considering I'm relatively new to programming and Eclipse gives me no errors. Any help would be much appreciated, as this is plaguing my class files at the moment.
Thanks,
Daniel

Your for loop condition is wrong. You want the condition to be true to continue looping, and false to stop.
Try
for (int x=0; x < 10; x++)
For more information, here's the Java tutorial on for loops.

#rgettman gave the reason your code didn't work above.
The way the for loop works is in the brackets the first variable is where the loop starts (i.e. 'x=0'), the second variable is the condition (i.e. 'x<= 10'), and the third is what to do for each loop (i.e. 'x++').
You had "x==10" for the condition, so for the first scenario where x was equal to "0", the loop ended because it was NOT equal to "10". So you want it to be "x<=10" (x is less than or equal to 10); this will go through 11 loops.

rgettman is completely correct. A for loop should be used as so:
for is a type of loop in java that will take three parameters separated by semicolons ;
The first parameter will take a variable such as int i = 0; to create a simple integer at 0.
The second parameter will take a condition such as i < 10, to say while the i integer is less than
The third and final parameter will take an incrementing value like, i++, i--, i +=5, or something to that effect.
This part should like like for(int i = 0; i < 10; i++) so far.
Now you need the brackets { and }. Inside of the brackets you will perform an action. Like you wanted to print "test" to the console.
for(int i = 0; i < 10; i++) {
System.out.println("test");
}
This would print "test" 10 times into the console. If you wanted to see what number i was at, you could simply say,
for(int i = 0; i < 10; i++) {
System.out.println(i); // Current value of i
}
Hope this was of use to you!

Break in nested for loops [duplicate]

This question already has answers here:
Closed 10 years ago.
Possible Duplicate:
How to Break from main/outer loop in a double/nested loop?
I have the following situation:
for(int i = 0; i < schiffe.length-1; i++){
if(schiffe[i].schaden){
schlepper.fliege(schiffe[i].x,
schiffe[i].y,
schiffe[i].z);
schlepper.wirdAbgeschleppt = schiffe[i];
for(int k = 0; k < stationen.length-1; k++){
if(stationen[k].reparatur == null){
schlepper.fliege(stationen[k].x,
stationen[k].y,
stationen[k].z);
break;
}
}
}
}
I want to
schlepper.fliege(stationen[k].x,
stationen[k].y,
stationen[k].z);
be performed once and then break out of the inner loop and continue with the for(int i... loop. So I used a break in my code. But I am not really sure if this is right. Does the break cause a break for all loops or just for the second loop?

It breaks only the inner loop, and therefore does what you want. To break more than one level, in Java, you can use a "labelled break" like so:
schiffe_loop:
for(int i = 0; i < schiffe.length-1; i++){
some_stuff();
for(int k = 0; k < stationen.length-1; k++){
if (something_really_bad_happened()) {
break schiffe_loop;
}
}
}
But usually you will not need this.
You may consider making a separate method for the inner loop anyway; it's something you can easily give a name to ("find_available_station" or something like that), and will probably need somewhere else.
Also, please be aware that your loops right now will miss the last element of each array. Think carefully about why you are using < instead of <=; it's exactly so that you use every value from 0 up to but not including the specified one.

break will break the innermost loop, in your case 2nd loop.
To make it break the outer loop you can use a labeled break as:
OUTER:for(...) {
for(...) {
break OUTER;
}
}

break only breaks out of the innermost loop.

break will cause break for closest loop only (second loop)

Just the second one. You can use "goto" of course.

Break statement terminates the closest enclosing loop or switch statement in which it appears in many languages but you can try it and be sure 100%.

put the inner two loops in a function and use return to break out of both of them.

If you need more control, you can use a labeled break. More info here. As others have said, break will close the closest loop.

What about using a boolean you call 'found' and use it like this:
while(!found) {
for(...) {
//todo
}
}

I Think You Can Do One More Thing..
for(int k = 0; k < stationen.length-1; k++){
if(stationen[k].reparatur == null){
schlepper.fliege(stationen[k].x,
stationen[k].y,
stationen[k].z);
k = stationen.length + 1 ;
}
}

iterator for loops with break

let say my code look like below
for(..)
for(..)
for(..){
break; //this will break out from the most inner loop OR all 3 iterated loops?
}

Your example will break out of the innermost loop only. However, using a labeled break statement, you can do this:
outer:
for(..)
for(..)
for(..){
break outer; //this will break out from all three loops
}

This will only break out from the inner loop. You can also define a scope to break out from. More from the language specs:
A break statement with no label
attempts to transfer control to the
innermost enclosing switch, while, do,
or for statement of the immediately
enclosing method or initializer block;
this statement, which is called the
break target, then immediately
completes normally.

Yes, without labels it will break only the most inner loop.
Instead of using labels you can put your loops in a seperated function and return from the function.
class Loop {
public void loopForXx() {
untilXx();
}
private void untilXx() {
for()
for()
for()
if(xx)
return;
}
}

From the most inner loop :)
int i,j,k;
for(i = 0; i < 2; i++)
for(j = 0; j < 2; j++)
for(k = 0; k < 2; k++)
{
printf("%d %d %d\n", i, j, k);
break;
}
Will produce :
0 0 0
0 1 0
1 0 0
1 1 0

You should take a look here: http://java.sun.com/docs/books/tutorial/java/nutsandbolts/branch.html

as often mentioned i don't like to break with a label eather. so while in a for loop most of the time i'm adding a boolean varible to simple exit the loop.. (only if i want to break it of cause;))
boolean exit = false;
for (int i = 0; i < 10 && !exit; i++) {
for (int j = 0; j < 10 && !exit; j++) {
exit = true;
}
}
this is in my opinion more elegant than a break..

Many people here don't like labels and breaking. This technique can be compared to using a 'goto' statement, a flow control statement which allows jumping out of a block of code in a non-standard way, obliviating use of pre- and post conditions. Edsger Dijkstra published a famous article in Communications of the ACM, march 1968, 'Goto statement considered harmful' (it's a short read).
Using the same reasoning presented in the article, returning from inside an iteration as suggested by TimW is also bad practice. If one is strict, to create readable code, with predictable entry- and exit points, one should initialize the variable which will hold the return value (if any) at the beginning of the method and return only at the end of a mehod.
This poses a challenge when using an iteration to perform a lookup. To avoid using break or return one inevitably ends up with a while-loop with a regular stop condition and some boolean variable to indicate that the lookup has succeeded:
boolean targetFound = false;
int i = 0;
while (i < values.size() && ! targetFound ) {
if (values.get(i).equals(targetValue)) {
targetFound = true;
}
}
if (!targetFound) {
// handle lookup failure
}
Ok, this works, but it seems a bit clunky to me. First of all I have to introduce a boolean to detect lookup success. Secondly I have to explicitly check targetFound after the loop to handle lookup failure.
I sometimes use this solution, which I think is more concise and readable:
lookup: {
for(Value value : values) {
if (value.equals(targetValue)) {
break lookup;
}
}
// handle lookup failure here
}
I think breaking (no pun intended) the rule here results in better code.

it will breake from most inner loop,
if you want to break from all, you can hold a variable and change its value when you want to break, then control it at the beginning of each for loop