CODEWITHSUNDEEP
javastringobjectmethodsequals
iyea070
iyea070

Reputation: 31

Java: Checking if a String is equal to a String

I have an issue where I am trying to compare an object's name (String) to another String, and I've tried using .equals() as well as == but neither seem to work in my case.

The code I have right now is:

public boolean checkingObjectName(String checkName)
{
    for (int i=0; i<count; i++) //where 'count' has a value of 3
    {
        if (product[i].getName().equals(checkName)) //where product[i] has been initialised
        {
            return true;
        }
        else
        {
            return false;
        }
    }
}

The program always returns false, even if the name that has been set to product[i] is the same as the parameter given. I've tried looking at other questions relating to .equals() and == and other String references but I have not had any luck in finding something that relates to my problem.

I have seen people use compareTo(), but I'm not sure if that is necessary in my code, and I'm not completely sure on how to use it.

EDIT: As said by Houssni in the comments, I have just realised that the return statement ends the loop and method. Is it possible to check each product's name without having the method terminated after the first check, and have it return a boolean value?

EDIT 2: I have modified the code to how the answers that have been provided say, which is:

public boolean checkingObjectName(String checkName)
{
    for (int i=0; i<count; i++) //where 'count' has a value of 3
    {
        if (product[i].getName().equals(checkName)) //where product[i] has been initialised
        {
            return true;
        }
    }
    return false;
}

I still get the same issue with the product[i].getName() not being equal to checkName and the method returning false, even though they should equal. Any possibilities on why this is happening, because I've looked through my code and I'm not sure.

Edit 3: The only other code that relates to the block of code above is the input of the parameter from another class, which is:

String checkName = JOptionPane.showInputDialog("Enter the name: ");
while (storingProducts.checkingObjectName(checkName) == false) //assume for storingProducts
{
    JOptionPane.showMessageDialog(null, "No products were found. Please re-input name.");
    checkName = JOptionPane.showInputDialog("Enter the name: ");
    storingProducts.checkingObjectName(checkName);
}
if (storingProducts.checkingObjectName(checkName) == true)
//extra code

So, that's all the code relating to my issue. I'm still not sure why the method returns false, though both values are receiving the same String value.

Edit 4: The product and count are coming from the class with the checkingObjectName method:

public class Store
{
    private Product[] product; //Product is another class that just sets and gets
    private int count=3;

    public Store()
    {
        product = new Product[count];
        for (int i=0; i<count; i++)
        {
            product[i] = new Product();
        }
    //extra code

SOLUTION

I fixed the issue: instead of using .equals(), I tried using .equalsIgnoreCase() and it worked.

Upvotes: 0

Views: 1988

Answers (4)

Chris M
Chris M

Reputation: 13

There are two ways to compare strings:

  • The first is to compare via addresses of the string. Such as: string blue = string red.
  • The second way to compare strings is through values. This can be done by using the string.equals("StringValue").

Upvotes: 1

Psycho Punch
Psycho Punch

Reputation: 6892

How about collecting the names into a List (or Set) and check if checkName matches?

public boolean checkObjectName(final String checkName) {    
    List<String> productNames = new ArrayList<String>();
    for (Product prod : product) {
        productNames.add(prod.getName());
    }
    return productNames.contains(checkName);
}

Note that this will only work if you're comparing case-sensitive strings. Alternatively,

public boolean checkObjectName(final String checkName) {    
    List<String> productNames = new ArrayList<String>();
    for (Product prod : product) {
        productNames.add(prod.getName().toLowerCase());
    }
    return productNames.contains(checkName.toLowerCase());
}

If you do not like this approach, you can use the ones given already, and replace equals with equalsIgnoreCase.

Upvotes: 0

Christian Tapia
Christian Tapia

Reputation: 34146

Since you have a return statement that will be reached on every posible situation (if condition is true or false), the method will always exit on the first iteration.

What can you do? If you want to return true if the name exists in the array and false otherwise, you can do:

public boolean checkingObjectName(String checkName)
{
    for (int i=0; i<count; i++) //where 'count' has a value of 3
    {
        if (product[i].getName().equals(checkName))
            return true;
    }
    return false; // if after all elements has been checked 
                  // and none was equal to 'checkName', return 'false'
}

Upvotes: 0

shmosel
shmosel

Reputation: 50716

The method is returning as soon as it hits count 0 and it doesn't find a match. If you want to loop through your array until you find a matching name, your code should look like this:

public boolean checkingObjectName(String checkName)
{
    for (int i=0; i<count; i++) //where 'count' has a value of 3
    {
        if (product[i].getName().equals(checkName)) //where product[i] has been initialised
        {
            return true;
        }
    }
    return false;
}

Upvotes: 7

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