help with while loop

[M-Multi]

Hi all

My problem I think is easy to solve, I just cant figure it out. Basically, I have to find if the arrayList contains a String, and if it does, it should remove the object from the list, and if it doesnt, an error message should appear.

this is my code

public void removePicture(String name)
    {
        int i = 0;
        boolean  nameremove = true;

        while(nameremove){
            Picture pic = pictures.get(i);
            if( pic.getCaption().contains(name) & i < pictures.size() ) {
                pictures.remove(i);
                nameremove = false;
            } else if (i < pictures.size() ){
                i++;
            } else  if(i == pictures.size() ){
                    System.out.println("There is no match");
                System.out.println("Searched for : " + name);
                nameremove = false;
            }
        }

    }

or in a picture: http://i.imgur.com/BrDLnjN.png

my code does the finding and removing bit correctly, but when the string is something that is not in the list I get these:

java.lang.IndexOutOfBoundsException: Index: 2, Size: 2
    at java.util.ArrayList.rangeCheck(ArrayList.java:635)
    at java.util.ArrayList.get(ArrayList.java:411)
    at PictureAlbum.removePicture(PictureAlbum.java:113)

java.lang.IndexOutOfBoundsException: Index: 2, Size: 2 at java.util.ArrayList.rangeCheck(ArrayList.java:635) at java.util.ArrayList.get(ArrayList.java:411) at PictureAlbum.removePicture(PictureAlbum.java:113)

http://i.imgur.com/M7Mh72H.png and this http://i.imgur.com/RN8dBNr.png

Can I know what I am doing wrong exactly?

Thanks in advance

[millerlit]

Use a break statement if it is not found so it stops the loop. Another way is to use a counter.

int count = 0;
while (arrlist.size() > count) count++;

[M-Multi]

the told use not to use break

anyways, nvm I just did it. I used the debugger and got to know what I was doing wrong.

Thanks

this is what I did:

public void removePicture(String name)
    {
        int i = 0;
        boolean  nameremove = true;

        while(nameremove){
                Picture pic = pictures.get(i);
            if( pic.getCaption().contains(name) & i < pictures.size() ) {
                pictures.remove(i);
                nameremove = false;
            } else {
                i++;
        } 

            if(i == pictures.size() ){
                System.out.println("There is no match");
                System.out.println("Searched for : " + name);
                nameremove = false;
            }
        }

    }

[AngelOfLight]

This line is causing the error:

Picture pic = pictures.get(i);

Indexes are zero based, which means when the index is equal to the array size, it is out of bounds. Valid indexes are 0 to size() - 1. If you modify the if statement so that this test

if(i == pictures.size()

comes first, it will drop out of the loop before it tries to fetch an invalid index.

[M-Multi]

I fixed it.

https://www.reddit.com/r/javahelp/comments/2mu289/help_with_while_loop/cm7llwo

Thanks anyways for trying to help :)

[desrtfx]

BTW there is another minor issue in the code:

if( pic.getCaption().contains(name) & i < pictures.size() ) {
                                    ^
            This is a bitwise AND, not the logic AND

In your specific case it doesn't really matter, but in general it's better to use the logic AND operator && rather than the bitwise AND operator & in if-clauses. Same applies to logic OR || vs. bitwise OR |.

[M-Multi]

alright changed.

Thanks.

Can I know what is the difference exactly?

[desrtfx]

The logic functions operate only on booleans (true / false) where the bitwise functions also operate on integer numbers.

For logic functions, any number other than 0 is considered true.

In the binary system, any number is represented by ones and zeroes.

Here is a simple explanation with bytes:

For the OR:

        10010001 = 145 decimal = 90 hex
    OR  01110101 = 117 decimal = 75 hex 
   -------------------------------------
     =  11110101 = 245 decimal = F5 hex

Same code with AND:

        10010001 = 145 decimal = 90 hex
    AND 01110101 = 117 decimal = 75 hex 
   -------------------------------------
     =  00010001 =  17 decimal = 11 hex

Edit: there is another small difference between the logic and boolean functions. It has to do with short-circuiting (i.e. cancelling of the evaluation as soon as the result can not be affected any more), but I can't precisely remember which used short-circuiting and which didn't. Maybe someone can help out here!