我有listView显示来自MySQL DB的图像和文本。到目前为止还可以，但现在我想知道如果点击某个项目从数据库中打开该ID，该如何制作。示例ListView 1与数据库中的id=1一致。ListView 2与id=2一样，依此类推。当我单击第2项以从DB打开该ID时。知道我该怎么办？
这是加载listview的xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:minHeight="50dp"
android:orientation="vertical" >
<LinearLayout
android:layout_width="300dp"
android:layout_height="wrap_content"
android:orientation="horizontal"
android:background="@drawable/buttons"
android:layout_marginTop="10dp"
>
<ImageView
android:id="@+id/image"
android:layout_width="50dp"
android:layout_height="50dp"
/>
<TextView
android:id="@+id/name"
android:layout_width="300dp"
android:layout_height="wrap_content"
android:paddingBottom="10dp"
android:paddingLeft="5dp"
android:paddingTop="15dp"
android:text="" />
</LinearLayout>
</LinearLayout>
这是我认为需要解决的代码部分
public class Restaurants extends Activity {
ListView listView;
TextView textView, textView1;
private StockAdaptor stockAdaptor;
String jsonResult = null;
ImageView image;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.restaurants); //Just a listView, shown below
listView = (ListView) findViewById(android.R.id.list);
textView = (TextView) findViewById(R.id.name);
image = (ImageView) findViewById(R.id.image);
new JsonReadTask().execute("http://link/GetRestaurants.php");
RelativeLayout.LayoutParams lp = new RelativeLayout.LayoutParams(listView.getLayoutParams());
lp.setMargins(10, 10, 0, 0);
listView.setLayoutParams(lp);
textView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent intent = new Intent(Restaurants.this, RestaurantInformation.class);
startActivity(intent);
}
});
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
return true; //No options
}
public void onStart() {
super.onStart();
stockAdaptor = new StockAdaptor(this); //Create a new StockAdaptor
}
public static String strFromStream(InputStream in) throws IOException { //Simple function, getting a String from an InputStream
StringBuilder out = new StringBuilder();
BufferedReader breader = new BufferedReader(new InputStreamReader(in));
String cline;
String newLine = System.getProperty("line.separator");
while ((cline = breader.readLine()) != null) {
out.append(cline);
out.append(newLine);
}
return out.toString();
}
private class StockAdaptor extends BaseAdapter { //The stocks list adaptor
class ViewHolder {
TextView name;
//TextView menu;
ImageView image;
}
private LayoutInflater layoutInflater;
private RestaurantStrings[] stocks = null; //Array of stocks
private ListView stocksListView = null;
public StockAdaptor(Context context) {
super();
layoutInflater = LayoutInflater.from(context);
}
public void setStockList(RestaurantStrings[] stocksinfo) {
this.stocks = stocksinfo;// //////////////LITERALLY THIS
}
@Override
public int getCount() {
return stocks.length;
}
@Override
public Object getItem(int position) {
return stocks[position];
}
public RestaurantStrings[] getAll() { //Return the array of stocks
return stocks;
}
@Override
public long getItemId(int position) {
return 0;
}
public View getView(int position, View convertView, ViewGroup parent) {
ViewHolder holder; //New holder
if (convertView == null) {
convertView = layoutInflater.inflate(R.layout.restaurant_second, null);
holder = new ViewHolder();
// Creates the new viewHolder define above, storing references to the children
holder.name = (TextView) convertView.findViewById(R.id.name);
//holder.menu = (TextView) convertView.findViewById(R.id.menu);
holder.image = (ImageView) convertView.findViewById(R.id.image);
if (holder.image != null) {
if (holder.image.getDrawable() == null) {
new ImageDownloaderTask(holder.image, null)
.execute(stocks[position].image); //Download the image using the image
}
}
convertView.setTag(holder);
} else {
holder = (ViewHolder) convertView.getTag();
}
holder.name.setText(stocks[position].name);
//holder.menu.setText(stocks[position].menu);
return convertView;
}
}
private class JsonReadTask extends AsyncTask<String, Void, String> {
@Override
protected String doInBackground(String... params) {
if (URLUtil.isValidUrl(params[0])) {
final AndroidHttpClient client = AndroidHttpClient.newInstance("Android");
final HttpGet getRequest = new HttpGet(params[0]);
try {
HttpResponse response = client.execute(getRequest);
final HttpEntity httpentity = response.getEntity();
if (httpentity != null){
InputStream inputStream = null;
try {
inputStream = httpentity.getContent();
jsonResult = strFromStream(inputStream);
Log.i("", jsonResult);
return jsonResult;
} catch (IllegalArgumentException e) {
//
} finally {
httpentity.consumeContent();
}
}
} catch (ClientProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
client.close();
}
}
return null;
}
@Override
protected void onPostExecute(String result) {
ListDrwaer();
}
}// end async task
// build hash set for list view
public void ListDrwaer() {
//Log.d("data from server", "data: " + jsonResult.toString());
try {
if (jsonResult!=null) {
JSONObject jsonResponse = new JSONObject(jsonResult);
JSONArray jsonMainNode = jsonResponse.optJSONArray("restaurants");
Vector<RestaurantStrings> vstocks = new Vector<RestaurantStrings>();
if(jsonMainNode == null)
{
Log.e("If is null", "jsonMainNode is null");
return;
}
for (int i = 0; i < jsonMainNode.length(); i++) {
JSONObject jsonChildNode = jsonMainNode.getJSONObject(i);
RestaurantStrings stock = new RestaurantStrings();
stock.image = jsonChildNode.getString("image");
stock.name = jsonChildNode.optString("name");
//stock.menu = jsonChildNode.optString("menu");
//stock.imgPath = jsonChildNode.getString("imgPath");
Log.e("err", stock.image + " " + stock.name);
vstocks.add(stock);
}
RestaurantStrings[] stocks = new RestaurantStrings[jsonMainNode.length()];
int stockscount = jsonMainNode.length();
for (int n = 0; n < stockscount; n++)
{
stocks[n] = vstocks.get(n);
}
stockAdaptor.setStockList(stocks);
listView.setAdapter(stockAdaptor);
} else {
Toast.makeText(getApplicationContext(), "Error; jsonResult null",
Toast.LENGTH_SHORT).show();
}
} catch (JSONException e) {
Toast.makeText(getApplicationContext(), "Error" + e.toString(),
Toast.LENGTH_SHORT).show();
}
}
private class ImageDownloaderTask extends AsyncTask<String, Void, Bitmap> {
private final WeakReference<ImageView> imageViewReference;
public ImageDownloaderTask(ImageView imageView, View view) {
imageViewReference = new WeakReference<ImageView>(imageView);
}
@Override
// Actual download method, run in the task thread
protected Bitmap doInBackground(String... params) {
// params comes from the execute() call: params[0] is the url.
return downloadBitmap(params[0]);
}
@Override
// Once the image is downloaded, associates it to the imageView
protected void onPostExecute(Bitmap bitmap) {
if (isCancelled()) {
bitmap = null;
}
if (imageViewReference != null) {
ImageView imageView = imageViewReference.get();
if (imageView != null) {
if (bitmap != null) {
imageView.setImageBitmap(bitmap);
} else {
//
}
}
}
}
Bitmap downloadBitmap(String url) {
if(URLUtil.isValidUrl(url)){
final AndroidHttpClient client = AndroidHttpClient.newInstance("Android");
final HttpGet getRequest = new HttpGet(url);
try {
HttpResponse response = client.execute(getRequest);
final int statusCode = response.getStatusLine().getStatusCode();
if (statusCode != HttpStatus.SC_OK) {
Log.w("ImageDownloader", "Error " + statusCode
+ " while retrieving bitmap from " + url);
return null;
}
final HttpEntity entity = response.getEntity();
if (entity != null) {
InputStream inputStream = null;
try {
inputStream = entity.getContent();
try {
byte[] buffer = new byte[8192];
int bytesRead;
ByteArrayOutputStream output = new ByteArrayOutputStream();
while ((bytesRead = inputStream.read(buffer)) != -1) {
output.write(buffer, 0, bytesRead);
}
return BitmapFactory.decodeByteArray(output.toByteArray(), 0, output.toByteArray().length);
} catch (IllegalArgumentException e) {
e.printStackTrace();
return null;
}
} finally {
if (inputStream != null) {
inputStream.close();
}
entity.consumeContent();
}
}
} catch (Exception e) {
getRequest.abort();
Log.w("ImageDownloader", "Error while retrieving bitmap from " + url);
} finally {
if (client != null) {
client.close();
}
}
return null;
}
return null;
}
}
}
如果我尝试输入onCreate()一个setOnClickListener，您可以看到该应用提供"Unfortunately your app has stopped"
更新
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".Activity"
android:background="#D3D3D3">
<ImageView
android:id="@+id/image"
android:layout_width="0dp"
android:layout_height="0dp"
android:layout_alignParentLeft="true"
android:layout_centerVertical="true"
/>
<ListView
android:id="@id/android:list"
android:layout_width="300dp"
android:layout_height="match_parent"
android:layout_toRightOf="@+id/image"
android:layout_alignParentTop="true"
android:divider="@android:color/transparent"
android:dividerHeight="5dp" >
</ListView>
</RelativeLayout>
错误
11-05 13:37:26.498: E/AndroidRuntime(1493): FATAL EXCEPTION: main
11-05 13:37:26.498: E/AndroidRuntime(1493): Process: com.reserveme, PID: 1493
11-05 13:37:26.498: E/AndroidRuntime(1493): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.reserveme/com.reserveme.Restaurants}: java.lang.NullPointerException
11-05 13:37:26.498: E/AndroidRuntime(1493): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2195)
11-05 13:37:26.498: E/AndroidRuntime(1493): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
11-05 13:37:26.498: E/AndroidRuntime(1493): at android.app.ActivityThread.access$800(ActivityThread.java:135)
11-05 13:37:26.498: E/AndroidRuntime(1493): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
11-05 13:37:26.498: E/AndroidRuntime(1493): at android.os.Handler.dispatchMessage(Handler.java:102)
11-05 13:37:26.498: E/AndroidRuntime(1493): at android.os.Looper.loop(Looper.java:136)
11-05 13:37:26.498: E/AndroidRuntime(1493): at android.app.ActivityThread.main(ActivityThread.java:5017)
11-05 13:37:26.498: E/AndroidRuntime(1493): at java.lang.reflect.Method.invokeNative(Native Method)
11-05 13:37:26.498: E/AndroidRuntime(1493): at java.lang.reflect.Method.invoke(Method.java:515)
11-05 13:37:26.498: E/AndroidRuntime(1493): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
11-05 13:37:26.498: E/AndroidRuntime(1493): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
11-05 13:37:26.498: E/AndroidRuntime(1493): at dalvik.system.NativeStart.main(Native Method)
11-05 13:37:26.498: E/AndroidRuntime(1493): Caused by: java.lang.NullPointerException
11-05 13:37:26.498: E/AndroidRuntime(1493): at com.reserveme.Restaurants.onCreate(Restaurants.java:69)
11-05 13:37:26.498: E/AndroidRuntime(1493): at android.app.Activity.performCreate(Activity.java:5231)
11-05 13:37:26.498: E/AndroidRuntime(1493): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
11-05 13:37:26.498: E/AndroidRuntime(1493): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2159)
11-05 13:37:26.498: E/AndroidRuntime(1493): ... 11 more
答案 0 :(得分：3)
我也在我的一个项目中使用ListView。要在listview中获取触摸/单击的位置，我已将ClickHandler注册到ListView（而不是列表中的项目）。 在你的例子中，ID等于位置，所以我认为你也可以这样做。
listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, final View view, int position, long id) {
Intent intent = new Intent(Restaurants.this, RestaurantInformation.class);
intent.putExtra("myID", position);
startActivity(intent);
}
});
在新的活动中，您可以调用以下内容来获取ID：
Intent intent = getIntent();
if (intent.getExtras() != null) {
myID = (Integer) intent.getExtras().get("myID");
}