如何使用listview顯示兩個string - Android 台灣中文網

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2012-9-30 22:40 上傳

package com.listvw;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.ArrayList;
import java.util.List;
import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.ListView;
public class MysqltestActivity extends Activity {
Button button;
String WebURL ="http://192.192.155.75/listview.aspx";
List<String> userid;
List<String> text;
private ListView listView;
int itemIndex = 0;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
listView=(ListView)findViewById(R.id.lva);
getdata();
}
private void getdata()
{
userid = new ArrayList<String>();
text = new ArrayList<String>();
String urlData = "";
urlData = GetURLDate();
Parser(urlData);
final ArrayAdapter<String> aa;
aa = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_2,text);
listView.setAdapter(aa);
}
public String GetURLDate()
{
String urlData = null;
try{
HttpURLConnection httpUrlconnection = null;
URL url = new URL(WebURL);
httpUrlconnection = (HttpURLConnection)url.openConnection();
httpUrlconnection.setDoInput(true);
httpUrlconnection.setDoOutput(true);
httpUrlconnection.connect();
BufferedReader in = new BufferedReader(
new InputStreamReader(httpUrlconnection.getInputStream()));
String decodedString;
while ((decodedString = in.readLine()) != null) {
urlData += decodedString;
}
in.close();
httpUrlconnection.disconnect();
}
catch(Exception e){
Log.e("ERROR", e.toString());
}
return urlData;
}
public void Parser(String urlData){
String temp = null;
int end = 0;
int start =0;
int counter = 0;
do{
start = urlData.indexOf("<td>", end+1);
end = urlData.indexOf("</td>", start+1);
temp = urlData.substring(start+4, end);
if ( !temp.equals("-") )
userid.add(temp);
else
userid.add(" ");
start = urlData.indexOf("<td>", end+1);
end = urlData.indexOf("</td>", start+1);
temp = urlData.substring(start+4, end);
if ( !temp.equals("-") )
text.add(temp);
else
text.add(" ");
counter++;
}while(counter < 10);
}
}

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作者: 不知火羽 時間: 2012-9-30 23:06
本帖最後由不知火羽於 2012-9-30 23:38 編輯

你是用ArrayAdapter只能存一個欄位的資料
請改用SimpleAdapter試試看
首先先將抓下來資料一個一個的欄位和其值放到HashMap<String,String>內
再用ArrayList<HashMap<String,String>>將一筆一筆資料裝進去
再來是要準備1個Layout作為放資料的模版
最後再放進SimpleAdapter

SimpleAdapter的寫法外面有教學可以看

先宣告ArrayList<HashMap<String,String>>

ArrayList<HashMap<String,String>> datas;

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74行修改的部分

public void Parser(String urlData){
String temp = null;
int end = 0;
int start =0;
int counter = 0;
do{
HashMap<String,String> hm = new HashMap<String,Object>(); //先實體化HashMap作為放資料的容器
start = urlData.indexOf("<td>", end+1);
end = urlData.indexOf("</td>", start+1);
temp = urlData.substring(start+4, end);
if ( !temp.equals("-") )
hm.put("userid",temp); //將userid丟到HashMap
else
hm.put("userid","");
start = urlData.indexOf("<td>", end+1);
end = urlData.indexOf("</td>", start+1);
temp = urlData.substring(start+4, end);
if ( !temp.equals("-") )
hm.put("text",temp); //將text丟到HashMap
else
hm.put("text","");
datas.add(hm); //將前面HashMap封裝的資料丟到ArrayList中(就是說將一筆資料轉成HashMap再丟進ArrayList)
counter++;
}while(counter < 10);
}

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35行修改的部分

private void getdata()
{
ArrayList<HashMap<String,String>> datas = new ArrayList<HashMap<String,String>>();
String urlData = "";
urlData = GetURLDate();
Parser(urlData);
final String[] items = {"userid","text"} //有幾個欄位就幾個欄位請注意順序
final int[] viewId = {R.id.textViewUserid,R.id.textViewText} //請建立一個新的Layout上面放兩的textView來作顯示userid和text使用
final SimpleAdapter sa;
sa = new SimpleAdapter(this, datas,R.layout.datas_list(你所創的layout名稱),items,viewId);
listView.setAdapter(sa);
}

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Layout的做法就不多加說明簡單來說就是開一個新的Layout
再拖兩個TextView進去(你要顯示多少資料欄位就拖都多少進來)，TextView怎麼擺，你的ListView就怎麼顯示

上面 items和viewId這兩個陣列是互相對應的

作者: wind8894 時間: 2012-9-30 23:43
本帖最後由 wind8894 於 2012-9-30 23:45 編輯

我照你上面這樣修改過後，會變得無法執行欸

是不是public class MysqltestActivity extends Activity

要改成public class MysqltestActivity extends ListActivity

還有81行，用object會錯誤，改成string就可以，是不是跟這邊有關呢?
HashMap<String,String> hm = new HashMap<String,String>();

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.widget.Button;
import android.widget.ListView;
import android.widget.SimpleAdapter;
public class MysqltestActivity extends Activity {
Button button;
String WebURL ="http://192.192.155.75/listview.aspx";
List<String> userid;
List<String> text;
ArrayList<HashMap<String,String>> datas;
private ListView listView;
int itemIndex = 0;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
listView=(ListView)findViewById(R.id.lva);
getdata();
}
private void getdata()
{
ArrayList<HashMap<String,String>> datas = new ArrayList<HashMap<String,String>>();
String urlData = "";
urlData = GetURLDate();
Parser(urlData);
final String[] items = {"userid","text"}; //有幾個欄位就幾個欄位請注意順序
final int[] viewId = {R.id.user_id,R.id.user_text}; //請建立一個新的Laylout上面放兩的textView來作顯示userid和text使用
final SimpleAdapter sa;
sa = new SimpleAdapter(this, datas,R.layout.user,items,viewId);
listView.setAdapter(sa);
}
public String GetURLDate()
{
String urlData = null;
try{
HttpURLConnection httpUrlconnection = null;
URL url = new URL(WebURL);
httpUrlconnection = (HttpURLConnection)url.openConnection();
httpUrlconnection.setDoInput(true);
httpUrlconnection.setDoOutput(true);
httpUrlconnection.connect();
BufferedReader in = new BufferedReader(
new InputStreamReader(httpUrlconnection.getInputStream()));
String decodedString;
while ((decodedString = in.readLine()) != null) {
urlData += decodedString;
}
in.close();
httpUrlconnection.disconnect();
}
catch(Exception e){
Log.e("ERROR", e.toString());
}
return urlData;
}
public void Parser(String urlData){
String temp = null;
int end = 0;
int start =0;
int counter = 0;
do{
HashMap<String,String> hm = new HashMap<String,String>();
start = urlData.indexOf("<td>", end+1);
end = urlData.indexOf("</td>", start+1);
temp = urlData.substring(start+4, end);
if ( !temp.equals("-") )
hm.put("userid",temp);
else
hm.put("userid","");
start = urlData.indexOf("<td>", end+1);
end = urlData.indexOf("</td>", start+1);
temp = urlData.substring(start+4, end);
if ( !temp.equals("-") )
hm.put("text",temp);
else
hm.put("text","");
datas.add(hm);
counter++;
}while(counter < 10);
}
}

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作者: 不知火羽 時間: 2012-10-1 09:58
本帖最後由不知火羽於 2012-10-1 10:02 編輯

HashMap<String,String> hm = new HashMap<String,String>();
是HashMap<String,String>才對

如果是HashMap<String,Object>的話
可能是我筆誤這點抱歉

這點非public class MysqltestActivity extends Activity
要改成public class MysqltestActivity extends ListActivity

其實不需要如果你的layout有ListView其實不需要用到ListActivity

如果無法執行的話請把LOG給我看照道理應該是可以執行的

作者: wind8894 時間: 2012-10-1 10:29
本帖最後由 wind8894 於 2012-10-1 10:31 編輯

我在想會不會是因為我用List<String> userid; 這樣宣告userid使 HashMap<String,String>在跑的時候出錯呢?

我去查了一下似乎有HashMap<String,List<String>>這樣的用法

10-01 02:26:51.470: E/AndroidRuntime(410): FATAL EXCEPTION: main
10-01 02:26:51.470: E/AndroidRuntime(410): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.mysqltest/com.mysqltest.MysqltestActivity}: java.lang.NullPointerException
10-01 02:26:51.470: E/AndroidRuntime(410): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1647)
10-01 02:26:51.470: E/AndroidRuntime(410): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663)
10-01 02:26:51.470: E/AndroidRuntime(410): at android.app.ActivityThread.access$1500(ActivityThread.java:117)
10-01 02:26:51.470: E/AndroidRuntime(410): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931)
10-01 02:26:51.470: E/AndroidRuntime(410): at android.os.Handler.dispatchMessage(Handler.java:99)
10-01 02:26:51.470: E/AndroidRuntime(410): at android.os.Looper.loop(Looper.java:123)
10-01 02:26:51.470: E/AndroidRuntime(410): at android.app.ActivityThread.main(ActivityThread.java:3683)
10-01 02:26:51.470: E/AndroidRuntime(410): at java.lang.reflect.Method.invokeNative(Native Method)
10-01 02:26:51.470: E/AndroidRuntime(410): at java.lang.reflect.Method.invoke(Method.java:507)
10-01 02:26:51.470: E/AndroidRuntime(410): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
10-01 02:26:51.470: E/AndroidRuntime(410): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
10-01 02:26:51.470: E/AndroidRuntime(410): at dalvik.system.NativeStart.main(Native Method)
10-01 02:26:51.470: E/AndroidRuntime(410): Caused by: java.lang.NullPointerException
10-01 02:26:51.470: E/AndroidRuntime(410): at com.mysqltest.MysqltestActivity.Parser(MysqltestActivity.java:100)
10-01 02:26:51.470: E/AndroidRuntime(410): at com.mysqltest.MysqltestActivity.getdata(MysqltestActivity.java:43)
10-01 02:26:51.470: E/AndroidRuntime(410): at com.mysqltest.MysqltestActivity.onCreate(MysqltestActivity.java:33)
10-01 02:26:51.470: E/AndroidRuntime(410): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
10-01 02:26:51.470: E/AndroidRuntime(410): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1611)
10-01 02:26:51.470: E/AndroidRuntime(410): ... 11 more

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作者: 不知火羽 時間: 2012-10-1 12:12
本帖最後由不知火羽於 2012-10-1 12:16 編輯

重點是這一個

ComponentInfo{com.mysqltest/com.mysqltest.MysqltestActivity}: java.lang.NullPointerException

請將36行

ArrayList<HashMap<String,String>> datas = new ArrayList<HashMap<String,String>>();

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改成

datas = new ArrayList<HashMap<String,String>>();

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就不會有問題了

datas已經在前面被宣告了就不必getdata()內再被宣告如過被後面的函數重新宣告的話就會出現NullPointerException的錯誤
因為後面Parser(String urlData)抓不到getdata()內部宣告變數的值

另外
List<String> userid;
List<String> text;
並不需要到用到可以拿掉

因為SimpleAdapter是透過List<Map<String,Object>>的形式來送資料的

作者: wind8894 時間: 2012-10-1 14:56
本帖最後由 wind8894 於 2012-10-1 15:07 編輯

如果要做到當點擊某個listview欄位時

跳出一個dialog

但是裡面的內容怎麼不是listview上顯示的，而且有{userid=...,text=....}這樣

登錄/註冊後可看大圖