我正在使用纽约时代电影评论API制作电影评论应用，API给了我一个字符串“short_summary”，我有一个类将API中的所有信息转换为ListView，我想创建一个将向用户显示评论摘要的新活动，但我知道如何获取此信息的唯一方法就是使用MovieArrayAdapter做同样的事情。
有没有办法只能从用户点击列表的评论中获取short_summary？
MainActivity.java
package br.com.pedro.pedrodaumas;
import android.annotation.TargetApi;
import android.content.Context;
import android.content.Intent;
import android.os.AsyncTask;
import android.os.Build;
import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.design.widget.TextInputEditText;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.LayoutInflater;
import android.view.View;
import android.view.Menu;
import android.view.MenuItem;
import android.view.inputmethod.InputMethodManager;
import android.widget.AdapterView;
import android.widget.LinearLayout;
import android.widget.ListView;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLEncoder;
import java.util.ArrayList;
import java.util.List;
public class MainActivity extends AppCompatActivity {
private List<Movie> movieList = new ArrayList<>();
private MovieArrayAdapter movieArrayAdapter;
private ListView movieListView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
movieListView = (ListView) findViewById(R.id.movieListView);
movieArrayAdapter = new MovieArrayAdapter(this, movieList);
movieListView.setAdapter(movieArrayAdapter);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
TextInputEditText search_bar;
search_bar = (TextInputEditText) findViewById(R.id.search_bar);
URL url = createURL(search_bar.getText().toString());
if(url != null){
dismissKeyboard(search_bar);
GetMovieTask getLocalMovieTask = new GetMovieTask();
getLocalMovieTask.execute(url);
}else {
Snackbar.make(findViewById(R.id.coordinatorLayout), R.string.invalid_url,
Snackbar.LENGTH_LONG).show();
}
}
});
movieListView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
switch (position) {
default:
Intent nextActivity = new Intent(MainActivity.this, ShortReview.class);
startActivity(nextActivity);
break;
}
}
});
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, 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();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
private void dismissKeyboard (View view){
InputMethodManager imm = (InputMethodManager)getSystemService(Context.INPUT_METHOD_SERVICE);
imm.hideSoftInputFromWindow(view.getWindowToken(),0);
}
private URL createURL (String movie){
String apiKey = getString (R.string.api_key);
String baseUrl = getString(R.string.nyt_url);
try{
String urlString = baseUrl + "?api_key=" + apiKey + "&query=" + URLEncoder.encode (movie, "UTF-8");
return new URL(urlString);
}
catch( Exception e){
e.printStackTrace();
}
return null;
}
private class GetMovieTask extends AsyncTask<URL, Void, JSONObject> {
@TargetApi(Build.VERSION_CODES.KITKAT)
@Override
protected JSONObject doInBackground(URL... params) {
HttpURLConnection connection = null;
try {
connection = (HttpURLConnection) params[0].openConnection();
int response = connection.getResponseCode();
if (response == HttpURLConnection.HTTP_OK){
StringBuilder builder = new StringBuilder ();
try (BufferedReader reader = new BufferedReader(new InputStreamReader(connection.getInputStream()))){
String line;
while ((line = reader.readLine()) != null){
builder.append(line);
}
}
catch (IOException e){
Snackbar.make(findViewById(R.id.coordinatorLayout), R.string.read_error, Snackbar.LENGTH_LONG).show();
e.printStackTrace();
}
return new JSONObject(builder.toString());
}
}
catch (Exception e){
Snackbar.make(findViewById(R.id.coordinatorLayout), R.string.connect_error, Snackbar.LENGTH_LONG).show();
e.printStackTrace();
}
finally{
if (connection != null){
connection.disconnect();
}
}
return null;
}
protected void onPostExecute(JSONObject movie) {
convertJSONToArrayList (movie);
movieArrayAdapter.notifyDataSetChanged();
movieListView.smoothScrollToPosition(0);
}
}
private void convertJSONToArrayList (JSONObject forecast){
movieList.clear();
try{
JSONArray results = forecast.getJSONArray("results");
for (int i = 0; i < results.length(); i++) {
JSONObject movie = results.getJSONObject(i);
if(movie.isNull("multimedia")){
movieList.add(new Movie(movie.getString("display_title"),
movie.getString("publication_date"),
"image", movie.getString("summary_short")));
}else {
JSONObject multimedia = movie.getJSONObject("multimedia");
movieList.add(new Movie(movie.getString("display_title"),
movie.getString("publication_date"),
multimedia.getString("src"), movie.getString("summary_short")));
}
}
}
catch (JSONException e){
e.printStackTrace();
}
}
}
Movie.java
package br.com.pedro.pedrodaumas;
public class Movie {
public final String title;
public final String publication_date;
public final String iconURL;
public final String short_summary;
public Movie(String title,String publication_date, String iconName, String short_summary) {
this.title = title;
this.publication_date = publication_date;
this.iconURL = iconName;
this.short_summary = short_summary;
}
}
MovieArrayAdapter.java
package br.com.pedro.pedrodaumas;
import android.annotation.TargetApi;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.AsyncTask;
import android.os.Build;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.ImageView;
import android.widget.TextView;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
public class MovieArrayAdapter extends ArrayAdapter<Movie> {
private static class ViewHolder{
ImageView movieImage;
TextView description;
TextView publication_date;
}
private Map<String, Bitmap> bitmaps = new HashMap<>();
public MovieArrayAdapter (Context context, List<Movie>
forecast){
super (context, -1, forecast);
}
public View getView(int position, View convertView, ViewGroup parent) {
Movie review = getItem (position);
ViewHolder viewHolder;
if (convertView == null){
viewHolder = new ViewHolder();
LayoutInflater inflater = LayoutInflater.from(getContext());
convertView = inflater.inflate(R.layout.complete_review, parent, false);
viewHolder.movieImage = (ImageView)convertView.findViewById(R.id.movieImage);
viewHolder.description = (TextView)convertView.findViewById(R.id.description);
viewHolder.publication_date = (TextView)convertView.findViewById(R.id.publication_date);
convertView.setTag(viewHolder);
}
else{
viewHolder = (ViewHolder)convertView.getTag();
}
if(review.iconURL == "image"){
viewHolder.movieImage.setImageResource(R.drawable.ic_import_contacts_white_24dp);
}
else{
new LoadImageTask (viewHolder.movieImage).execute (review.iconURL);
}
Context context = getContext();
viewHolder.description.setText(review.title);
viewHolder.publication_date.setText(review.publication_date);
return convertView;
}
private class LoadImageTask extends AsyncTask<String, Void, Bitmap> {
private ImageView imageView;
public LoadImageTask (ImageView imageView){
this.imageView = imageView;
}
@TargetApi(Build.VERSION_CODES.KITKAT)
@Override
protected Bitmap doInBackground(String... params) {
Bitmap bitmap = null;
HttpURLConnection connection = null;
try{
URL url = new URL(params[0]);
connection = (HttpURLConnection) url.openConnection();
try(InputStream inputStream = connection.getInputStream ()){
bitmap = BitmapFactory.decodeStream(inputStream);
bitmaps.put (params[0], bitmap);
}
catch (Exception e){
e.printStackTrace();
}
}
catch (Exception e){
e.printStackTrace();
}
finally{
connection.disconnect();
}
return bitmap;
}
protected void onPostExecute(Bitmap bitmap) {
imageView.setImageBitmap(bitmap);
}
}
}
ShortReview.java
package br.com.pedro.pedrodaumas;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.widget.TextView;
public class ShortReview extends AppCompatActivity {
private TextView short_summary;
private Movie review;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.movie_description);
short_summary = (TextView) findViewById(R.id.short_summary);
short_summary.setText("test");
}
}
答案 0 :(得分：2)
感谢来自（https://forums.xamarin.com/discussion/38235/setcontentview-of-mainactivity-gives-null-pointer-after-adding-preference-xml-to-project）的Zainal Fahrudin和Nilanchala 我能够通过使用getSummary并将其添加到putExtra来解决我的问题。
以下是我改变的内容：
MainAtivity
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
switch (position) {
default:
Movie review = movieArrayAdapter.getItem(position);
Intent nextActivity = new Intent(MainActivity.this, ShortReview.class);
nextActivity.putExtra("summary", review.getsummary());
startActivity(nextActivity);
break;
}
}
});
}
电影
public String getsummary() {
return short_summary;
}
ShortReview
private TextView short_summary;
private String s_summary;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.movie_description);
Intent intent = getIntent();
if (null != intent) {
s_summary = intent.getStringExtra("summary");
}
short_summary = (TextView) findViewById(R.id.short_summary);
short_summary.setText(s_summary);
}
答案 1 :(得分：0)
您可以使用intent extra，
Intent intent = new Intent(FirstActivity.this,SecondActivity.class);
intent.putExtra("short_summary", "the summary is here");
startActivity(intent)
然后获取第二个活动的字符串值
Bundle bundle = getIntent().getExtras();
if (bundle!=null){
String summary = bundle.getString("short_summary");
}