Multi tool use

How to check if an item in an ArrayList<String> does not contain a certain word?

I want to use a for loop like this:

`button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Object.setList();

for(int i = 0; i < Object.getList.size(); i++)
if(!Object.getList.get(i).trim().toLowerCase().contains("hello")) {
Toast.makeText(getContext(), "List does not contain "Hello", Toast.LENGTH_LONG).show;
}
}`


This is my model:

public class Object {
private ArrayList<String> mArrayList;

public void setList() {
mArrayList = new Arraylist<>();
mArrayList.add("Random Message");
mArrayList.add("ZZZZ")
}

public ArrayList<String> getList() {
return mArrayList;
}
}


I still keep getting the Toast message, but it works just fine when i use:

if(!Object.getList().toString.trim().toLowerCase().contains("hello"))


3 Answers
3

I am not really sure how this expression:

Object.getList().toString.trim().toLowerCase().contains("hello")


works. Consider two adjacent elements: "he" and "llo". Even in this case your solution would state that the string "hello" exists in the ArrayList. Since there is ho hashing in ArrayList, the only solution is via brute force (Giving a performance of O(n)). Here is the solution:

ArrayList

ArrayList

O(n)

for(String element: list) {
if (str.equalsIgnoreCase(element)) {
// Found
}
}


Object.getList().toString.trim().toLowerCase().contains("hello")

"hello world!, random message, zzzz"

Object.getList().toString.trim().toLowerCase().contains("hello")

If you want to do it one line, do it like this:

if(object.getList().stream().noneMatch(it -> "hello".equalsIgnoreCase(it))){
// ...
}


This will work if you are using Java 8.

If your aim is to check if each string in the list does not have "hello" and show toast each time then you can do so :

Object.getList().forEach(el -> {
if(!el.toLowerCase().contains("hello")){
// show toast
}
})


If your aim is to check if each string in the list does not have "hello" and show toast only once the do so :

if(Object.getList().stream().noneMatch(el -> !el.toLowerCase().contains("hello"))){
// toast
}


If you wanna simply check if there is any sting that matches any element of list then do what @SatyendraKumar sugested.

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