Android JSONObject – How can I loop through a flat JSON object to get each key and value

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The question:

{
  "key1": "value1",
  "key2": "value2",
  "key3": "value3"
}

How I can get each item’s key and value without knowing the key nor value beforehand?

The Solutions:

Below are the methods you can try. The first solution is probably the best. Try others if the first one doesn’t work. Senior developers aren’t just copying/pasting – they read the methods carefully & apply them wisely to each case.

Method 1

Use the keys() iterator to iterate over all the properties, and call get() for each.

Iterator<String> iter = json.keys();
while (iter.hasNext()) {
    String key = iter.next();
    try {
        Object value = json.get(key);
    } catch (JSONException e) {
        // Something went wrong!
    }
}

Method 2

Short version of Franci’s answer:

for(Iterator<String> iter = json.keys();iter.hasNext();) {
    String key = iter.next();
    ...
}

Method 3

You’ll need to use an Iterator to loop through the keys to get their values.

Here’s a Kotlin implementation, you will realised that the way I got the string is using optString(), which is expecting a String or a nullable value.

val keys = jsonObject.keys()
while (keys.hasNext()) {
    val key = keys.next()
    val value = targetJson.optString(key)        
}

Method 4

You shold use the keys() or names() method. keys() will give you an iterator containing all the String property names in the object while names() will give you an array of all key String names.

You can get the JSONObject documentation here

http://developer.android.com/reference/org/json/JSONObject.html

Method 5

Take a look at the JSONObject reference:

http://www.json.org/javadoc/org/json/JSONObject.html

Without actually using the object, it looks like using either getNames() or keys() which returns an Iterator is the way to go.


All methods was sourced from stackoverflow.com or stackexchange.com, is licensed under cc by-sa 2.5, cc by-sa 3.0 and cc by-sa 4.0

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