Shulou(Shulou.com)06/02 Report--

This article shows you what is the difference between optString and getString in JSON. The content is concise and easy to understand. It will definitely brighten your eyes. I hope you can get something through the detailed introduction of this article.

Native parsing json methods are commonly used:

JSONObject jsonObject = new JSONObject ()

String str1 = jsonObject.optString ("6 no 6")

String str2 = jsonObject.optString ("6 no 6", "default 6")

Try {

String str3 = jsonObject.getString ("666")

} catch (JSONException e) {

E.printStackTrace ()

}

One: the difference between optString and getString:

OptString will return the empty string "" or the specified default value when you cannot get the value you want, while getString will throw an exception.

OptString can resolve the exception caused by the absence or absence of a server field so that the program crashes.

It is recommended to use optString to avoid exceptions such as missing interface fields and data type conversion of value.

Second: getString () can get any type of data?

First, the source code of JSONObject is as follows:

Partial source code of JSONObject class:

/ * *

* Returns the value mapped by {@ code name} if it exists, coercing it if

* necessary, or throws if no such mapping exists.

*

* @ throws JSONException if no such mapping exists.

, /

Public String getString (String name) throws JSONException {

Object object = get (name)

String result = JSON.toString (object); / / any type is strongly converted to string

If (result = = null) {

Throw JSON.typeMismatch (name, object, "String"); / / throws a resolution for null

}

Return result

}

/ * *

* Returns the value mapped by {@ code name} if it exists, coercing it if

* necessary, or the empty string if no such mapping exists.

, /

Public String optString (String name) {

Return optString (name, "")

}

/ * *

* Returns the value mapped by {@ code name} if it exists, coercing it if

* necessary, or {@ code fallback} if no such mapping exists.

, /

Public String optString (String name, String fallback) {

Object object = opt (name)

String result = JSON.toString (object)

Return result! = null? Result: fallback;// is not a null result. Specify a value for an empty result.

}

You can see that any type of value of getString or optString will be forcefully converted to string before return

This is why there has never been a data type exception when you have been using getString to get fields.

GetString throws an exception only if it does not have the field or if the result is null. Type does not cause an exception.

The above is what is the difference between optString and getString in JSON. Have you learned any knowledge or skills? If you want to learn more skills or enrich your knowledge reserve, you are welcome to follow the industry information channel.

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.