How to remove all duplicates of ints in an array java -

i needed create method remove occurrences of integers in array. when integers removed, whole list needs shifted down empty spaces filled next integers. currently, method removes 1 occurrence of given integer.

public void removeall(int val) {     (int n = 0; n < list.length; n++) {  //goes through each integer         if (list[n] == val) {  //checks if value user enters             (int j = n; j < list.length - 1; j++) {                 list[j] = list[j + 1];             }             list[elements - 1] = 0;  //elements amount of elements in array             elements--;         }     } } 

you close:

i recommend not using list.length rather elements throughout. otherwise, algorithm break when val = 0 , list contains 0.

public void removeall(int val){     for(int n = 0; n <elements;n++){  // < -- change list.length elements         if(list[n] == val){               (int j = n; j<elements-1;j++){ // < -- change list.length elements                 list[j]=list[j+1];         }         list[elements-1]=0;          elements--;         n--;  // <-- add line not skip on 'n + 1'th term     }  } } 

the problem iterating on collection skipping next term after removal.

for example, val = 2 , list = 1 2 2 3 4 4:

the algorithm identifies , removes value:

1 2 2 3 4 4   ^ 

after array looks , next position checked n has been incremented @ next item in collection. it's not hard see problematic when items match removal criteria next each other (adjacent) in example.

1 2 3 4 4 0     ^ 

in order compensate event - need decrement n n--; when encounter item removed collection. keeps n looking @ same index in array until index no longer occupied to-be-removed item (aka items match removal criteria adjacent).

update

what happens if count of array not used upper limit throughout , val = 0 array contains @ least 1 0?

i'll keep theme , illustrate issue example.

let val = 0 , list = 1 2 0 3 4 4. usual, algorithm identifies , removes value.

1 2 0 3 4 4     ^ 

now array looks this:

1 2 3 4 4 0     ^ 

however, since algorithm still iterating on collection until index equal list.length still valued @ 6 (it's not being decremented elements). algorithm end @ faux item @ index 5 of collection. trouble begins.

1 2 3 4 4 0           ^ 

the index never move there going adjacent 0 we're adding them end of collection signify unused indexes! collection this:

0 0 0 0 0 0           ^ 

in following iteration - indexoutofboundsexception thrown java list[-1] = 0 occur.

hope helps!