Android Java; 我怎样才能parsing从资产文件夹本地JSON文件到一个ListView

我目前正在开发一个物理应用程序，应该显示公式列表，甚至解决其中的一些（唯一的问题是ListView ）

这是我的主要布局

  <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="fill_parent" android:layout_height="wrap_content" android:measureWithLargestChild="false" android:orientation="vertical" tools:context=".CatList" > <RelativeLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:background="@drawable/titlebar" > <TextView android:id="@+id/Title1" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_centerHorizontal="true" android:layout_centerVertical="true" android:text="@string/app_name" android:textAppearance="?android:attr/textAppearanceLarge" android:textColor="#ff1c00" android:textIsSelectable="false" /> </RelativeLayout> <ListView android:id="@+id/listFormulas" android:layout_width="match_parent" android:layout_height="wrap_content" > </ListView> </LinearLayout> 

这是我的主要活动

 package com.wildsushii.quickphysics; import java.io.IOException; import java.io.InputStream; import java.util.ArrayList; import java.util.HashMap; import org.json.JSONException; import org.json.JSONObject; import android.os.Bundle; import android.app.Activity; import android.content.Context; import android.content.res.AssetManager; import android.view.Menu; import android.widget.ListView; public class CatList extends Activity { public static String AssetJSONFile (String filename, Context context) throws IOException { AssetManager manager = context.getAssets(); InputStream file = manager.open(filename); byte[] formArray = new byte[file.available()]; file.read(formArray); file.close(); return new String(formArray); } @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_cat_list); ListView categoriesL = (ListView)findViewById(R.id.listFormulas); ArrayList<HashMap<String, String>> formList = new ArrayList<HashMap<String, String>>(); Context context = null; try { String jsonLocation = AssetJSONFile("formules.json", context); JSONObject formArray = (new JSONObject()).getJSONObject("formules"); String formule = formArray.getString("formule"); String url = formArray.getString("url"); } catch (IOException e) { e.printStackTrace(); } catch (JSONException e) { e.printStackTrace(); } //My problem is here!! } @Override public boolean onCreateOptionsMenu(Menu menu) { // Inflate the menu; this adds items to the action bar if it is present. getMenuInflater().inflate(R.menu.cat_list, menu); return true; } } 

我真的知道我可以做到这一点，而不使用JSON，但我需要更多的练习parsingJSON。 顺便说一下，这是JSON

  { "formules": [ { "formule": "Linear Motion", "url": "qp1" }, { "formule": "Constant Acceleration Motion", "url": "qp2" }, { "formule": "Projectile Motion", "url": "qp3" }, { "formule": "Force", "url": "qp4" }, { "formule": "Work, Power, Energy", "url": "qp5" }, { "formule": "Rotary Motion", "url": "qp6" }, { "formule": "Harmonic Motion", "url": "qp7" }, { "formule": "Gravity", "url": "qp8" }, { "formule": "Lateral and Longitudinal Waves", "url": "qp9" }, { "formule": "Sound Waves", "url": "qp10" }, { "formule": "Electrostatics", "url": "qp11" }, { "formule": "Direct Current", "url": "qp12" }, { "formule": "Magnetic Field", "url": "qp13" }, { "formule": "Alternating Current", "url": "qp14" }, { "formule": "Thermodynamics", "url": "qp15" }, { "formule": "Hydrogen Atom", "url": "qp16" }, { "formule": "Optics", "url": "qp17" }, { "formule": "Modern Physics", "url": "qp18" }, { "formule": "Hydrostatics", "url": "qp19" }, { "formule": "Astronomy", "url": "qp20" } ] } 

我已经尝试了很多东西，甚至删除整个项目，使一个新的:(

Answer 1

正如Faizan在他们的回答中所描述的那样：

首先使用下面的代码从您的集合文件中读取Json文件。

然后你可以简单的通过这个函数读取这个string返回

 public String loadJSONFromAsset() { String json = null; try { InputStream is = getActivity().getAssets().open("yourfilename.json"); int size = is.available(); byte[] buffer = new byte[size]; is.read(buffer); is.close(); json = new String(buffer, "UTF-8"); } catch (IOException ex) { ex.printStackTrace(); return null; } return json; } try { JSONObject obj = new JSONObject(loadJSONFromAsset()); JSONArray m_jArry = obj.getJSONArray("formules"); ArrayList<HashMap<String, String>> formList = new ArrayList<HashMap<String, String>>(); HashMap<String, String> m_li; for (int i = 0; i < m_jArry.length(); i++) { JSONObject jo_inside = m_jArry.getJSONObject(i); Log.d("Details-->", jo_inside.getString("formule")); String formula_value = jo_inside.getString("formule"); String url_value = jo_inside.getString("url"); //Add your values in your `ArrayList` as below: m_li = new HashMap<String, String>(); m_li.put("formule", formula_value); m_li.put("url", url_value); formList.add(m_li); } } catch (JSONException e) { e.printStackTrace(); } 

有关JSON的更多详细信息，请阅读此处

Answer 2

 { // json object node "formules": [ // json array formules { // json object "formule": "Linear Motion", // string "url": "qp1" } 

你在做什么

  Context context = null; // context is null try { String jsonLocation = AssetJSONFile("formules.json", context); 

所以换到

  try { String jsonLocation = AssetJSONFile("formules.json", CatList.this); 

parsing

我相信你从assests文件夹中得到string。

 try { String jsonLocation = AssetJSONFile("formules.json", context); JSONObject jsonobject = new JSONObject(jsonLocation); JSONArray jarray = (JSONArray) jsonobject.getJSONArray("formules"); for(int i=0;i<jarray.length();i++) { JSONObject jb =(JSONObject) jarray.get(i); String formula = jb.getString("formule"); String url = jb.getString("url"); } } catch (IOException e) { e.printStackTrace(); } catch (JSONException e) { e.printStackTrace(); }