trying to compare a String to a Hashtable key/value

Question

Hashtable<String, Integer> coordinates= new Hashtable<String, Integer>();
String value = (String) cb1.getSelectedItem();
if(value==coordinates.keys())

It gives me a "imcompatible operand types String and Enumeration" error, any idea how I can compare these two without a loop?

@javaguy its a combobox: final JComboBox cb1 = new JComboBox(Places1); — Commongrate, Dec 10 '16 at 13:59
And then: you never ever compare strings using == you use the equals method instead! — GhostCat, Dec 10 '16 at 14:01

score 3 · Accepted Answer · edited May 23 '17 at 11:45

You can't simply because a Set is a collection of Strings. Comparing would be like "I've got this bucket of apples and I got this apple, let's compare them". What you can do though is check whether the String is part of the Set, which is as simple as calling coordinates.keys().contains(value).

And regarding the comparison:
Don't compare Strings using ==. == compares by value, which would in case of Objects such as Strings be the reference. Use string1.equals(string2) instead. This topic is covered more extensively in this question

score 0 · Answer 2 · answered Dec 11 '16 at 11:46

Use the keySet method which will return a Collection. Then call contains on it with the selected value.

    Hashtable<String, Integer> coordinates= new Hashtable<String, Integer>();
    String value = (String) cb1.getSelectedItem();
    if (coordinates.keySet().contains(value)) {
        //Some action...
    }

trying to compare a String to a Hashtable key/value

2 Answers2