Check If Item Is in an Array/List

Check if a value exists in ArrayList

Just use ArrayList.contains(desiredElement). For example, if you're looking for the conta1 account from your example, you could use something like:

if (lista.contains(conta1)) {
    System.out.println("Account found");
} else {
    System.out.println("Account not found");
}

Edit:
Note that in order for this to work, you will need to properly override the equals() and hashCode() methods. If you are using Eclipse IDE, then you can have these methods generated by first opening the source file for your CurrentAccount object and the selecting Source > Generate hashCode() and equals()...

Check if item is in an array / list

Assuming you mean "list" where you say "array", you can do

if item in my_list:
    # whatever

This works for any collection, not just for lists. For dictionaries, it checks whether the given key is present in the dictionary.

Check if an arrayList contains an array

As you are creating different arrays (even if the contents are the same), contains will result false.

However, if you do this:

 List<String[]> action = new ArrayList<String[]>();
 String[] items = new String[]{"apple","ball"};   
 action.add(items);
 if (action.contains(items)) 
     System.out.println("Yes");

This will print Yes.
Also, some examples of the behaviour:

 String[] items = new String[]{"apple","ball"};   
 action.add(items);
 String[] clone = items.clone();
 String[] mirror = items;

 action.contains(clone); // false 
 action.contains(mirror); // true

 items[0]="horse";
 System.out.println(mirror[0]);        // "horse"
 System.out.println(clone[0]);         // "apple"
 System.out.println(action.get(0)[0]); // "horse"

 mirror[1]="crazy";
 System.out.println(clone[1]);         // "ball"
 System.out.println(action.get(0)[1]); // "crazy"
 System.out.println(items[1]);         // "crazy"

 clone[1]="yolo";
 System.out.println(action.get(0)[1]); // "crazy"
 System.out.println(items[1]);         // "crazy"
 System.out.println(mirror[1]);        // "crazy"

 System.out.println(action.get(0).hashCode());    //2018699554
 System.out.println(items.hashCode());            //2018699554
 System.out.println(clone.hashCode());            //1311053135
 System.out.println(mirror.hashCode());           //2018699554

---

Custom "contains"

The issue here is that if you want to search for an specific array afterwards, you'd lose the references and searching an item wouldn't be possible, not even replicating the array with the same exact values.

As a workaround, you could implement your own contains method. Something like:

If you wish to get the index:

static int indexOfArray(List<String[]> list, String[] twin)
{        
   for (int i=0;i<list.size();i++)
      if (Arrays.equals(list.get(i),twin))
           return i;
   return -1;
}

And then, call it like:

String[] toSearch = new String[]{"apple","ball"};
int index = indexOfArray(action, toSearch); 

if (index>0) 
    System.out.println("Array found at index "+index);
else
    System.out.println("Array not found");

If the index is bigger than -1, you can get your original array by just:

String[] myArray = action.get(index);

---

HashMap + identifier

An alternative would be storing the arrays into a HashMap by declaring an identifier for each array. For example:

Base64 ID

This will give the same result for the same values, as the encoded value is based on the entries, not the Object's reference.

 static String getIdentifier(String[] array)
 {
    String all="";
    for (String s : array)
        all+=s;
    return Base64.getEncoder().encodeToString(all.getBytes());
 }

And then you could:

Map<String, String[]> arrayMap= new HashMap<>();
String[] items = new String[]{"apple","pear", "banana"}; // *[1234] 
action.add(items);
arrayMap.put(getIdentifier(items), items); // id = QUJDYWFh
//....
//Directly finding the twin will fail
String[] toSearch = new String[]{"apple","pear", "banana"}; // *[1556]
System.out.println(action.contains(toSearch)); // false

//But if we get the identifier based on the values
String arrId = getIdentifier(toSearch); // id = QUJDYWFh
System.out.println(action.contains(arrayMap.get(arrId)));  //true

//arrayMap.get(arrId)->  *[1234]
//.....

Name.

Choose a representative name and use it as Id

Map<String, String[]> arrayMap= new HashMap<>();
String[] items = new String[]{"apple","pear", "banana"};
action.add(items);
arrayMap.put("fruits", items);
//...
System.out.println(action.contains(arrayMap.get("fruits"))); // true  
    

Checking if Object is instance of ListObject

I was wrong in my previous answer since i not fully understood your requirements.
if your added item is an Object you may add it without any problem as long as you Have a list of something.
You don't have to recreate the list

void add(Object toAdd) {
    Object obj = getObject();
    if (obj instanceof List<?>) {
        ((List<Object>)obj).add(toAdd);
        return;
    }
    throw new SomeException();
}

UPDATE

as answer to few comments, there is no problem to add any object to a list, and there is no problem to find out what type of object it is during iteration after it:

List<String> x1 = new ArrayList<String>();
Object c3 = x1;
x1.add("asdsad");
Integer y2 = new Integer(5);
if (c3 instanceof List<?>){
     ((List<Object>)c3).add((Object)y2);
}

for (Object i : (List<Object>)c3){
    if (i instanceof String){
        System.out.println("String: " + (String)i);
    }
    if (i instanceof Integer){
        System.out.println("Integer: "+ (Integer)i);
    }
}

How to check if an array in an arraylist contains a certain value?

@assylias suggestion to use the object oriented way is good, but his example does not tell if the list contains a transaction where one property has a certain value. This example does:

public class Test {

    public static void main(final String[] args) {
        final List<TransactionLine> transaction = new ArrayList<>();

        transaction.add(new TransactionLine(1, "some value"));
        transaction.add(new TransactionLine(2, "another value"));
        transaction.add(new TransactionLine(3, "yet another value"));

        System.out.println(containsName(transaction, "some value"));
        System.out.println(containsName(transaction, "non-existent value"));
    }

    // Iterates over all transactions until a transaction is found that has the
    // same name as specified in search
    private static boolean containsName(final List<TransactionLine> transaction, final String search) {
        for (final TransactionLine transactionLine : transaction) {
            if (transactionLine.getName().equals(search)) {
                return true;
            }
        }

        return false;
    }

    private static class TransactionLine {

        private int id;

        private String name;

        public TransactionLine(final int id, final String name) {
            this.id = id;
            this.name = name;
        }

        public int getId() {
            return id;
        }

        public void setId(final int id) {
            this.id = id;
        }

        public String getName() {
            return name;
        }

        public void setName(final String name) {
            this.name = name;
        }

    }

}

Here is an example with two classes (Transaction and TransactionLine):

Test:

public class Test {

    public static void main(final String[] args) throws Exception {
        final Transaction transaction = new Transaction();

        transaction.add("some name");
        transaction.add("another name");
        transaction.add("yet another name");

        System.out.println(transaction.containsName("some name"));
        System.out.println(transaction.containsName("non-existent name"));
    }

}

Transaction:

import java.util.ArrayList;
import java.util.List;

public class Transaction {

    private final List<TransactionLine> transactionLines = new ArrayList<>();

    public void add(final String name) {
        final TransactionLine tl = new TransactionLine(transactionLines.size(), name);

        transactionLines.add(tl);
    }

    public boolean containsName(final String name) {
        for (final TransactionLine transactionLine : transactionLines) {
            if (transactionLine.getName().equals(name)) {
                return true;
            }
        }

        return false;
    }

}

TransactionLine:

public class TransactionLine {

    private int id;

    private String name;

    public TransactionLine() {
    }

    public TransactionLine(final int id, final String name) {
        this.id = id;
        this.name = name;
    }

    public int getId() {
        return id;
    }

    public void setId(final int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(final String name) {
        this.name = name;
    }

}

How to check if a text contains an element of an ArrayList

i is a String. In that case list[i] does not make sense, since i inside of list[i] should be an index, which is an integer (e.g. list[0], list[1], but can not be list["hello"]).

So if you want to check that your text contains a String from list, you can use

if(text.contains(i))

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Also, be aware that your result of

text.replaceAll(" ", "%");

is being ignored. If you want to keep the altered text, you can do that by storing the result of the replace into a new, separate variable.

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