Sort Java Script Object literals

Question

I inherited a project that uses JSON to perform a series of operations as denoted by each object literal. I have zero experience with JSON and while the notation is straight forward, I'm finding working with the object literals less so.

Consider the following file:

[{
    "Name": "Hingle McCringleberry",
    "ID": "4"
},
{
    "Name": "Scoish Velociraptor Maloish",
    "ID": "1"
},
{
    "Name": "DGlester Hardunkichud",
    "ID": "3"
}]

Using Java, I want to sort them by ID. I saw this thread that talks about implementing a JavaScript sort method, but I'm unsure how to do this in practice. I'm using a JsonFactory and JsonParser to read and iterate over the file, but I need them to be sorted before I can process them.

Eric Galluzzo · Accepted Answer · 2013-02-14 17:53:29Z

2

Since you're using Jackson to parse these, I assume you must be parsing them into a List of some sort of object with an ID and name. If that is the case, simply write a standard Comparator. For example:

NamedObject.java:

public class NamedObject {
    // I'm using public fields instead of getters/setters for brevity,
    // since this is just sample code.

    @JsonProperty("ID")
    public int id;

    @JsonProperty("Name")
    public String name;
}

NamedObjectIdComparator.java:

public class NamedObjectIdComparator implements Comparator<NamedObject> {
    public int compare(NamedObject object1, NamedObject object2) {
        return object1.id - object2.id;
    }
}

Then, to sort the list of objects:

List<NamedObject> objects = // parse using JsonParser
Collections.sort(objects, new NamedObjectIdComparator());

answered Feb 14, 2013 at 17:53

Eric Galluzzo

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卢声远 Shengyuan Lu · Accepted Answer · 2013-02-14 17:54:03Z

0

I don't know much about jackson library, but I am sure jackson can convert JSON to Java List object (some methods call readValueXXX I guess).

Once we got a Java List, Collections.sort can do the sorting.

answered Feb 14, 2013 at 17:54

卢声远 Shengyuan Lu

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