Searching an ArrayList for a String; always return false

Question

I am having trouble with this method of my class. It always returns false. Passenger is a separate class. This is a method in my Train class which creates an array list of Passenger objects. I am making a method that will search the ArrayList passengerList for a Passanger object with the name as the parameter.

public boolean search(String a){
    Passenger temp;
    boolean query = false;
    for (int i =0; i<passengerList.size(); i++)
    {
        temp=passengerList.get(i);
        if (temp.getName() == a)
        {
            query = true;
        }
    }
    return query;
}

kosa · Accepted Answer · 2012-11-13 20:42:11Z

4

 if (temp.getName() == a)

should be

 if (temp.getName().equals(a))

String comparison should always use equals() method instead of == (except that strings literals).

if temp.getName() and a both not pointing to same object, == condition will fail.

== checks for references equality. equals() checks for content equality.

This tutorial may help you.

answered Nov 13, 2012 at 20:42

kosa

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1 Comment

jeanqueq Over a year ago

Thanks for helping the link you gave me explained a lot!

Vivin Paliath · Accepted Answer · 2012-11-13 20:42:52Z

2

if (temp.getName() == a) should be if (temp.getName().equals(a)).

The former compares references for equality. The latter actually checks to see if the string values are equal.

answered Nov 13, 2012 at 20:42

Vivin Paliath

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Comments

Alex · Accepted Answer · 2012-11-13 21:03:31Z

0

I would suggest writing this code more elegant and cleaner (with checking for null):

public boolean search(String a){  
    boolean query = false;
    for (Passenger temp : passengerList)
    {
        if (temp != null && temp.getName()!=null && temp.getName().equals(a))
        {
            query = true;
        }
    }
    return query;
}

answered Nov 13, 2012 at 21:03

Alex

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