Question

当我尝试获取JSONArray的长度时，Eclipse总是给我这个编译错误：

对于JSONArray类型
，方法length（）未定义

以下是代码：

import org.springframework.context.annotation.Scope;
import java.net.*;
import java.io.*;

import net.sf.json.JSONArray;
import net.sf.json.JSONObject;
import net.sf.json.JSONSerializer;
import javax.inject.Named;

@Named("search")
@Scope("request")

public class Search {

    private String query;
    private String result;
    private int num;


    public String getQuery() {
        return query;
      }
    public void setQuery(String query) {
        this.query = query;
      }
    public String getResult() {
        return this.result;
      }
    public void setResult(String result) {
        this.result = result;
      }
    public int getNum() {
        return this.num;
      }
    public void setNum(int num) {
        this.num = num;
      }


    public String send() {
         try 
        {
            //SEND REQUEST TO SOLR SERVER

            URL url = new URL("http://localhost:8983/solr/select/?q="+this.query +"&version=2.2&start=0&rows=100&indent=on&wt=json");

            BufferedReader in = new BufferedReader(new InputStreamReader(url.openStream()));
            String str;

            while ((str = in.readLine()) != null) 
            {
                this.result = this.result+str;
            }

            in.close();

            //CONVERT RESULT TO OBJECT


           this.result=this.result.substring(4);
           JSONObject json = (JSONObject) JSONSerializer.toJSON(this.result);
           JSONArray results = new JSONArray();
            json = json.getJSONObject("response");
            this.num = json.getInt("numFound");

            results = json.getJSONArray("docs");
            int num = results.length();

我不知道为什么会出现这个错误。这是怎么造成的，我该如何解决？

Answer 1

javadoc here没有显示JSONArray的length（）方法。因此错误。它确实有size（），那就是你所追求的吗？

Answer 2

让它更清晰的例子：假设personList是用户创建的类'Person'的arraylist，

$.ajax({

 success:function (resultData) {

var resultListData = resultData.personList;  // personList as a JSON Object got by Action response.
if(resultListData.length > 0){
   // process results
   $.each(resultListData, function (iter) {
          alert(resultListData[iter].personFirstName);
  }else{
     alert("No Data to display");
 }
}
});

对于JSONArray类型，方法length（）未定义

2 个答案: