我开发一个最后一年的项目和我被困在一个点。我得从我的数据库(MySQL数据库)获取医生的名字,并显示在列表视图。我是能够建立与服务器的连接,并检索值,但是当我试图查看列表视图中的值,应用程序崩溃!
我试图给出相同的例子的 [您好,视图,列表视图] [4] 的。
它的工作原理为predefined阵列像
私有String lv_arr [] = {机器人,iPhone,黑莓,AndroidPeople};
但对于一个字符串数组从数据库检索它显示了一个运行时间异常。有没有什么办法可以做到这一点?
包com.proj;
进口java.io.BufferedReader中;
进口的java.io.InputStream;
进口java.io.InputStreamReader中;
进口的java.util.ArrayList;
进口org.apache.http.HttpEntity;
进口org.apache.http.Htt presponse;
进口org.apache.http.NameValuePair;
进口org.apache.http.client.HttpClient;
进口org.apache.http.client.entity.UrlEn codedFormEntity;
进口org.apache.http.client.methods.HttpPost;
进口org.apache.http.impl.client.DefaultHttpClient;
进口org.apache.http.message.BasicNameValuePair;
进口org.json.JSONArray;
进口org.json.JSONException;
进口org.json.JSONObject;
进口android.widget *。
进口android.app.ListActivity;
进口android.app.Activity;
进口android.content.Intent;
进口android.os.Bundle;
进口android.util.Log;
进口android.widget.LinearLayout;
进口android.widget.TextView;
公共类凸出扩展ListActivity {
/ **第一次创建活动时调用。 * /
公众诠释N = 0;
公众诠释T = 0;
公众诠释我= 0;
公共字符串名称[] =新的String [30];
@覆盖
公共无效的onCreate(包savedInstanceState)
{
super.onCreate(savedInstanceState);
的setContentView(R.layout.main);
//创建一个粗观点 - 这确实应该通过布局资源设置
//但由于它的一个例子扑救声明它们的XML。
TextView的TXT =(TextView中)findViewById(R.id.tv);;
//调用方法运行数据检索
getServerData(KEY_121);
setListAdapter(新ArrayAdapter(这一点,
android.R.layout.simple_list_item_1,名));
}
公共静态最后弦乐KEY_121 =http://10.0.2.2/doc.php; //我在这里用我的真实IP地址。
私人字符串getServerData(字符串returnString){
InputStream的是= NULL;
字符串结果=;
//这一年要发送的数据。
ArrayList的<的NameValuePair> namevaluepairs中=新的ArrayList<的NameValuePair>();
nameValuePairs.add(新BasicNameValuePair(年,1970年));
// HTTP发布
尝试{
HttpClient的HttpClient的=新DefaultHttpClient();
HttpPost httppost =新HttpPost(KEY_121);
httppost.setEntity(新UrlEn codedFormEntity(namevaluepairs中));
HTT presponse响应= httpclient.execute(httppost);
HttpEntity实体= response.getEntity();
是= entity.getContent();
}
赶上(例外五){
Log.e(log_tag,错误的HTTP连接+ e.toString());
}
//转换响应串
尝试{
的BufferedReader读卡器=新的BufferedReader(新InputStreamReader的(就是,ISO-8859-1),8);
StringBuilder的SB =新的StringBuilder();
串线= NULL;
而((行= reader.readLine())!= NULL){
sb.append(行+\ N);
}
is.close();
结果= sb.toString();
}
赶上(例外五){
Log.e(log_tag,错误转换结果+ e.toString());
}
//解析JSON数据
尝试 {
JSONArray jArray =新JSONArray(结果);
对于(i = 0; I< jArray.length();我++)
{
的JSONObject json_data = jArray.getJSONObject(ⅰ);
N = jArray.length();
名称[I] = json_data.getString(姓名);
//获取输出到屏幕上
returnString + =\ñ\ t+ jArray.getJSONObject(我);
}
}
赶上(JSONException E)
{
Log.e(log_tag,错误分析数据+ e.toString());
e.printStackTrace();
}
返回returnString;
}
}
解决方案
您使用的是
1)
机器人:ID =@ + ID /列表
在ListView内,但如果你用ListActivity扩展的活动中,你必须使用
机器人:ID =@android:ID /列表
2。)
您返回的String []
在这里,不是字符串
私有String [] getServerData(字符串returnString){
.......
JSONArray jArray =新JSONArray(结果);
名称=新的String [jArray.length()];
对于(i = 0; I< jArray.length();我++)
{
的JSONObject json_data = jArray.getJSONObject(ⅰ);
名称[I] = json_data.getString(姓名);
}
返回名称;
}
而在ArrayAdapter,像这样做:
ArrayAdapter<字符串>适配器=新的ArrayAdapter<字符串>(这一点,android.R.layout.simple_list_item_1,getServerData(KEY_121));
setListAdapter(适配器);
I am developing a final year project and I am stuck at a point. I have to retrieve names of doctors from my database (MySQL database) and show it in a list view. I was able to establish a connection with the server and retrieve values, but when I tried to show the values in a list view, the application crashed!
I tried the same example given in [Hello, Views, List View][4].
It works for a predefined array like
private String lv_arr[]={"Android","iPhone","BlackBerry","AndroidPeople"};
but for a string array retrieved from the database it shows a run time exception. Is there any way I can achieve this?
package com.proj;
import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.ArrayList;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
import org.apache.http.client.HttpClient;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.message.BasicNameValuePair;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import android.widget.*;
import android.app.ListActivity;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.widget.LinearLayout;
import android.widget.TextView;
public class proj extends ListActivity {
/** Called when the activity is first created. */
public int n=0;
public int t=0;
public int i=0;
public String name[]=new String[30];
@Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
// Create a crude view - this should really be set via the layout resources
// but since its an example saves declaring them in the XML.
TextView txt=(TextView)findViewById(R.id.tv);;
//Call the method to run the data retrieval
getServerData(KEY_121);
setListAdapter(new ArrayAdapter(this,
android.R.layout.simple_list_item_1, name));
}
public static final String KEY_121 = "http://10.0.2.2/doc.php"; //I use my real IP address here.
private String getServerData(String returnString) {
InputStream is = null;
String result = "";
//The year data to send.
ArrayList<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>();
nameValuePairs.add(new BasicNameValuePair("year","1970"));
//HTTP post
try{
HttpClient httpclient = new DefaultHttpClient();
HttpPost httppost = new HttpPost(KEY_121);
httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
HttpResponse response = httpclient.execute(httppost);
HttpEntity entity = response.getEntity();
is = entity.getContent();
}
catch(Exception e){
Log.e("log_tag", "Error in http connection "+e.toString());
}
//Convert response to string
try{
BufferedReader reader = new BufferedReader(new InputStreamReader(is,"iso-8859-1"),8);
StringBuilder sb = new StringBuilder();
String line = null;
while ((line = reader.readLine()) != null) {
sb.append(line + "\n");
}
is.close();
result=sb.toString();
}
catch(Exception e){
Log.e("log_tag", "Error converting result "+e.toString());
}
//Parse JSON data
try {
JSONArray jArray = new JSONArray(result);
for(i=0;i<jArray.length();i++)
{
JSONObject json_data = jArray.getJSONObject(i);
n=jArray.length();
name[i]=json_data.getString("name");
//Get an output to the screen
returnString += "\n\t" + jArray.getJSONObject(i);
}
}
catch(JSONException e)
{
Log.e("log_tag", "Error parsing data "+e.toString());
e.printStackTrace();
}
return returnString;
}
}
解决方案
You are using
1.)
android:id="@+id/list"
inside the ListView, but if your extend an activity by ListActivity you have to use
android:id = "@android:id/list"
2.)
You return a String[]
here, not String
private String[] getServerData(String returnString) {
.......
JSONArray jArray = new JSONArray(result);
name = new String[jArray.length()];
for(i=0;i<jArray.length();i++)
{
JSONObject json_data = jArray.getJSONObject(i);
name[i]=json_data.getString("name");
}
return name;
}
And in ArrayAdapter, do it like this:
ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, getServerData(KEY_121));
setListAdapter(adapter);