I cant seem to figure out a way to use an ArrayList (2 or more indexes) to search within another ArrayList. For example, if list = [4,5,6,2,3,5,6] and searchlist = [5,6], index should = 1.
Anybody have any ideas?
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so are you looking for the occurrence of the numbers in the searchlist to be in your list in the order that it is in in searchlist? and it return the index?mig– mig2014-03-21 04:39:37 +00:00Commented Mar 21, 2014 at 4:39
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you want to search the second list within the first list.. right..??Dileep– Dileep2014-03-21 04:44:25 +00:00Commented Mar 21, 2014 at 4:44
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@mig Yea so if searchlist = [3,5], then index should = 40onetwo– 0onetwo2014-03-21 04:50:05 +00:00Commented Mar 21, 2014 at 4:50
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1See a similar post at stackoverflow.com/questions/3940194/…Setyo N– Setyo N2014-03-21 04:51:10 +00:00Commented Mar 21, 2014 at 4:51
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@Dileep Yea I want to search searchlist inside list0onetwo– 0onetwo2014-03-21 04:51:41 +00:00Commented Mar 21, 2014 at 4:51
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4 Answers
List has subList and equals. That's all you need.
import java.util.*;
import java.lang.*;
import java.io.*;
class TEST
{
public static void main (String[] args) throws java.lang.Exception {
List<Integer> list1 = Arrays.asList(1,2,3,4,5);
List<Integer> list2 = Arrays.asList(2,3);
for (int i=0; i<list1.size()-list2.size(); ++i) {
if (list1.subList(i, i+list2.size()).equals(list2)) {
System.out.println("found: "+i);
return;
}
}
System.out.println("not found");
}
}
Comments
Use pointers to your current indices
public int search(int[] list, int[] searchList) {
int listIndex = 0;
int searchListIndex = 0;
int foundIndex = -1;
while (listIndex != list.length) {
if (list[listIndex] == searchList[searchListIndex]) {
if (searchListIndex == 0) {
foundIndex = listIndex;
}
listIndex++;
searchListIndex++;
}
else {
listIndex++;
searchListIndex = 0;
foundIndex = -1;
}
}
return foundIndex;
}
Comments
Loop through the arrays in a nested loop. Then compare all values. If all values match up, then return the index:
list = [4,5,6,2,3,5,6]
searchlist = [5,6]
limit = list.size - serachList.size - 1
#make sure list's size is greater than or equal to searchList's size
for(i = 0 to limit)
for(j = 0 to searchList.size-1)
if(list[i + j] != searchList[j]) #found mismatch, so move on
break
if(j = searchList.size-1) #found complete match
return i
answered Mar 21, 2014 at 4:49
But I'm Not A Wrapper Class
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Comments
The simplest idea is to run a loop, get the first value of the searchlist and find that value in the other list. If you find the number, increment the indices of both the lists and check the values again, continue until the end of searchlist or until the end of the other list.
I am not posting the code as I would rather you try yourself first, and come back if you are stuck anywhere.
