How to iterate over json data with gson

JsonArray is an Iterable<JsonElement>. So you can use for in loop.

JsonObject jsonObject = new JsonParser().parse(jsonString).getAsJsonObject();
final JsonArray data = jsonObject.getAsJsonArray("data");
System.out.println("data : " + data);
System.out.println("recordsTotal : " + jsonObject.get("recordsTotal"));
List<String> list = new ArrayList<String>();
for (JsonElement element : data) {
    list.add(((JsonObject) element).get("part_number").getAsString());

}

Suppose class Name for Json Model is Example.

import com.google.gson.annotations.SerializedName;
import java.util.List;
public class Example {

    @SerializedName("recordsTotal")
    private Integer recordsTotal;
    @SerializedName("data")
    private List<Datum> data = null;

    public Integer getRecordsTotal() {
        return recordsTotal;
    }

    public void setRecordsTotal(Integer recordsTotal) {
        this.recordsTotal = recordsTotal;
    }

    public List<Datum> getData() {
        return data;
    }

    public void setData(List<Datum> data) {
        this.data = data;
    }

}

And suppose List of Data class name is Datum :-

import com.google.gson.annotations.SerializedName;
import java.util.List;
public class Datum {

    @SerializedName("part_number")

    private String partNumber;
    @SerializedName("part_type")

    private String partType;
    @SerializedName("id")

    private Integer id;
    @SerializedName("manufacturers")

    private List<String> manufacturers = null;

    public String getPartNumber() {
        return partNumber;
    }

    public void setPartNumber(String partNumber) {
        this.partNumber = partNumber;
    }

    public String getPartType() {
        return partType;
    }

    public void setPartType(String partType) {
        this.partType = partType;
    }

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public List<String> getManufacturers() {
        return manufacturers;
    }

    public void setManufacturers(List<String> manufacturers) {
        this.manufacturers = manufacturers;
    }

}

And then through Gson library we can convert json to java Model :

Example example = new Gson().fromJson(jsonString, new TypeToken<Example>() {}.getType());

Now we can get list of data though example model :-

List<Datum>  dataList = example.getData();

From dataList you can traverse and get all info.

If partNmber List we need then we can get in this way :-

 List<String> partNumberList = new ArrayList<>();
 for (Datum data : dataList) {
       partNumberList.add(data.getPartNumber());
  }

The given code will not guaranteed to 100% equivalent but it will help you to work.

First you have to create the class for your data objects:

class mydata {
    public String part_name;
    public String part_type;
    public int Id;
    public String manufacturers;
}

Your main method should look like

public static void main(String[] args) {

JSONObject obj = new JSONObject();
List<mydata> sList = new ArrayList<mydata>();

mydata obj1 = new mydata();
obj1.setValue("val1");
sList.add(obj1);

mydata obj2 = new mydata();
obj2.setValue("val2");
sList.add(obj2);

obj.put("list", sList);

JSONArray jArray = obj.getJSONArray("list");
for(int ii=0; ii < jArray.length(); ii++)
  System.out.println(jArray.getJSONObject(ii).getString("value"));
    }

For futher exploration you can use that link: https://gist.github.com/codebutler/2339666