我试图将ArrayList中的项目显示给ListView，但遇到了问题。当包含ListView的SearchActivity开始时，我给出了一个空白屏幕。任何人都可以打电话给我，为什么？
这里的SearchActivity.Java（顺便说一下，prettyprint函数用字符串填充ArrayList）
package com.example.activity2;
import java.util.ArrayList;
import java.util.Iterator;
import android.app.Activity;
import android.app.SearchManager;
import android.content.Intent;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import com.google.api.services.youtube.model.SearchResult;
public class SearchActivity extends Activity {
ListView lst;
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_search_activity);
Intent intent = getIntent();
if (Intent.ACTION_SEARCH.equals(intent.getAction())) {
String query = intent.getStringExtra(SearchManager.QUERY);
ArrayList<SearchResult> results = new ArrayList<SearchResult>();
Iterator<SearchResult> it = results.iterator();
SearchYoutube.prettyPrint(it, query);
lst = (ListView) findViewById(R.id.list);
ArrayAdapter<String> adapter = new ArrayAdapter(this, android.R.layout.simple_list_item_1, SearchYoutube.ytstuff);
lst.setAdapter(adapter);
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.search, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
}
这是相应的xml：
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="com.example.activity2.SearchActivity"
android:orientation="vertical" >
<ListView
android:id="@+id/list"
android:layout_width="309dp"
android:layout_height="309dp"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:layout_marginTop="52dp" >
</ListView>
</LinearLayout>
更新：
SearchYoutube.java：
package com.example.activity2;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.Properties;
import com.google.api.client.googleapis.json.GoogleJsonResponseException;
import com.google.api.client.http.HttpRequest;
import com.google.api.client.http.HttpRequestInitializer;
import com.google.api.services.youtube.YouTube;
import com.google.api.services.youtube.model.ResourceId;
import com.google.api.services.youtube.model.SearchListResponse;
import com.google.api.services.youtube.model.SearchResult;
import com.google.api.services.youtube.model.Thumbnail;
/**
* Print a list of videos matching a search term.
*
* @author Jeremy Walker
*/
public class SearchYoutube {
public static ArrayList<String> ytstuff = new ArrayList();
/**
* Define a global variable that identifies the name of a file that
* contains the developer's API key.
*/
private static final String PROPERTIES_FILENAME = "youtube.properties";
private static final long NUMBER_OF_VIDEOS_RETURNED = 25;
/**
* Define a global instance of a Youtube object, which will be used
* to make YouTube Data API requests.
*/
private static YouTube youtube;
/**
* Initialize a YouTube object to search for videos on YouTube. Then
* display the name and thumbnail image of each video in the result set.
*
* @param args command line args.
*/
public static void main(String[] args) {
// Read the developer key from the properties file.
Properties properties = new Properties();
try {
InputStream in = SearchActivity.class.getResourceAsStream("/" + PROPERTIES_FILENAME);
properties.load(in);
} catch (IOException e) {
System.err.println("There was an error reading " + PROPERTIES_FILENAME + ": " + e.getCause()
+ " : " + e.getMessage());
System.exit(1);
}
try {
// This object is used to make YouTube Data API requests. The last
// argument is required, but since we don't need anything
// initialized when the HttpRequest is initialized, we override
// the interface and provide a no-op function.
youtube = new YouTube.Builder(Auth.HTTP_TRANSPORT, Auth.JSON_FACTORY, new HttpRequestInitializer() {
public void initialize(HttpRequest request) throws IOException {
}
}).setApplicationName("youtube-cmdline-search-sample").build();
// Prompt the user to enter a query term.
String queryTerm = getInputQuery();
// Define the API request for retrieving search results.
YouTube.Search.List search = youtube.search().list("id,snippet");
// Set your developer key from the Google Developers Console for
// non-authenticated requests. See:
// https://console.developers.google.com/
String apiKey = properties.getProperty("youtube.apikey");
search.setKey(apiKey);
search.setQ(queryTerm);
// Restrict the search results to only include videos. See:
// https://developers.google.com/youtube/v3/docs/search/list#type
search.setType("video");
// To increase efficiency, only retrieve the fields that the
// application uses.
search.setFields("items(id/kind,id/videoId,snippet/title,snippet/thumbnails/default/url)");
search.setMaxResults(NUMBER_OF_VIDEOS_RETURNED);
// Call the API and print results.
SearchListResponse searchResponse = search.execute();
List<SearchResult> searchResultList = searchResponse.getItems();
if (searchResultList != null) {
prettyPrint(searchResultList.iterator(), queryTerm);
}
} catch (GoogleJsonResponseException e) {
System.err.println("There was a service error: " + e.getDetails().getCode() + " : "
+ e.getDetails().getMessage());
} catch (IOException e) {
System.err.println("There was an IO error: " + e.getCause() + " : " + e.getMessage());
} catch (Throwable t) {
t.printStackTrace();
}
}
/*
* Prompt the user to enter a query term and return the user-specified term.
*/
private static String getInputQuery() throws IOException {
String inputQuery = "";
System.out.print("Please enter a search term: ");
BufferedReader bReader = new BufferedReader(new InputStreamReader(System.in));
inputQuery = bReader.readLine();
if (inputQuery.length() < 1) {
// Use the string "YouTube Developers Live" as a default.
inputQuery = "YouTube Developers Live";
}
return inputQuery;
}
/*
* Prints out all results in the Iterator. For each result, print the
* title, video ID, and thumbnail.
*
* @param iteratorSearchResults Iterator of SearchResults to print
*
* @param query Search query (String)
*/
public static void prettyPrint(Iterator<SearchResult> iteratorSearchResults, String query) {
if (!iteratorSearchResults.hasNext()) { }
while (iteratorSearchResults.hasNext()) {
SearchResult singleVideo = iteratorSearchResults.next();
ResourceId rId = singleVideo.getId();
// Confirm that the result represents a video. Otherwise, the
// item will not contain a video ID.
if (rId.getKind().equals("youtube#video")) {
Thumbnail thumbnail = singleVideo.getSnippet().getThumbnails().getDefault();
for (int i=0;i<27;i=i+2)
for (int j= 1;j <28;i=i+2)
if (j-i == 1)
{
ytstuff.set(i,rId.getVideoId()); //first thing is video id
ytstuff.set(j,singleVideo.getSnippet().getTitle()); //second thing is title
}
}
}
}
}
答案 0 :(得分：0)
然后是，您的列表视图的适配器未提供任何内容。这就是活动空白的原因。此外，如果您未传递操作Intent.ACTION_SEARCH，则适配器将再次为空，从而导致空白活动。