嗨，我一直在使用我的第一个 android 应用程序，它开始变得有点缓慢和滞后。我以前做过 iPhone 应用程序，我知道我必须发布一些东西。所以我想我的问题是在避免内存泄漏方面为 android 编码的最佳实践是什么。从 JSON 提要加载数据并通常简化我的代码以使其更有效地改善用户体验？
您可以提供的任何帮助都会受到赞赏和对 android 的热情，但只是想确保我做对了
到目前为止，这是我的代码示例
public class HomeActivity extends ListActivity {
private MergeAdapter adapter=null;
private ArrayAdapter<String> arrayAdapter=null;
private ArrayAdapter<String> arrayAdapter2=null;
private ArrayAdapter<String> arrayAdapter3=null;
private static final String apiKey = "46fhr636gdbc737hjd92932dd";
private static final String apiUser = "android-app-v1";
private static final String ChosenTeam = null;
private static String ChosenMethod = null;
public String fulldata = null;
public String chosenLeagueId = "40";
public List<String> newsList = null;
public List<String> newsList2 = null;
public List<String> newsList3 = null;
public int newsAmount = 0;
long unixTimeStamp = System.currentTimeMillis() / 1000L;
//add Time Stamp to URL
//public String chosenMethod;
String newsFeedRequest = "1.0/website/" + chosenLeagueId + "/news?timestamp=" + unixTimeStamp;
String fixturesFeedURL = "https://website.com/_services/api/" + newsFeedRequest;
private int container;
private static String buildHmacSignature(String pKey, String pStringToSign)
{
String lSignature = "None";
try
{
Mac lMac = Mac.getInstance("HmacSHA256");
SecretKeySpec lSecret = new SecretKeySpec(pKey.getBytes(), "HmacSHA256");
lMac.init(lSecret);
byte[] lDigest = lMac.doFinal(pStringToSign.getBytes());
BigInteger lHash = new BigInteger(1, lDigest);
lSignature = lHash.toString(16);
if ((lSignature.length() % 2) != 0) {
lSignature = "0" + lSignature;
}
}
catch (NoSuchAlgorithmException lEx)
{
throw new RuntimeException("Problems calculating HMAC", lEx);
}
catch (InvalidKeyException lEx)
{
throw new RuntimeException("Problems calculating HMAC", lEx);
}
return lSignature;
}
public void checkPreferences(){
SharedPreferences preferences = getSharedPreferences("prefs", Context.MODE_PRIVATE);
final String ChosenMethodPref = preferences.getString("ChosenMethod", ChosenMethod);
Log.v("myapp", "ChosenMethod Home = " + ChosenMethodPref);
if (ChosenMethodPref.equals("Team")) {
setContentView(R.layout.homeactteam2);
newsAmount = 5;
} else {
setContentView(R.layout.homeact);
newsAmount = 10;
}
}
public void loadData(){String myhash = buildHmacSignature(apiKey, fixturesFeedURL);
HttpClient client = new DefaultHttpClient();
HttpPost post = new HttpPost(fixturesFeedURL);
List<NameValuePair> pairs = new ArrayList<NameValuePair>();
pairs.add(new BasicNameValuePair("requestToken", myhash));
pairs.add(new BasicNameValuePair("apiUser", apiUser));
try {
post.setEntity (new UrlEncodedFormEntity(pairs));
HttpResponse response = client.execute(post);
BufferedReader reader = new BufferedReader(new InputStreamReader(response.getEntity().getContent(), "UTF-8"));
String json = reader.readLine();
fulldata = String.valueOf(json);
Log.v("myApp","newsdata" + fulldata);
newsList = new ArrayList<String>();
newsList2 = new ArrayList<String>();
newsList3 = new ArrayList<String>();
JSONObject obj = new JSONObject(json);
JSONObject objData = obj.getJSONObject("data");
JSONArray jArray = objData.getJSONArray("news");
for(int t = 0; t < newsAmount; t++){
JSONObject newsTitleDict = jArray.getJSONObject(t);
newsList3.add(newsTitleDict.getString("title"));
}
for(int t = 0; t < 1; t++){
JSONObject newsTitleDict = jArray.getJSONObject(t);
newsList.add(newsTitleDict.getString("title"));
newsList2.add(newsTitleDict.getString("title"));
}
} catch (ClientProtocolException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
arrayAdapter = new ArrayAdapter<String>(this, R.layout.single_item, newsList);
arrayAdapter2 = new ArrayAdapter<String>(this, R.layout.single_item, newsList2);
arrayAdapter3 = new ArrayAdapter<String>(this, R.layout.single_item, newsList3);
ListView list = getListView();
list.setTextFilterEnabled(true);
LayoutInflater inflater = (LayoutInflater) this.getSystemService(Context.LAYOUT_INFLATER_SERVICE );
View header = inflater.inflate( R.layout.homeheader, list, false);
View header2 = inflater.inflate( R.layout.homeheader2, list, false);
View header3 = inflater.inflate( R.layout.homeheader3, list, false);
//setListAdapter (arrayAdapter);
adapter = new MergeAdapter();
adapter.addView(header);
adapter.addAdapter(arrayAdapter);
adapter.addView(header2);
adapter.addAdapter(arrayAdapter2);
adapter.addView(header3);
adapter.addAdapter(arrayAdapter3);
setListAdapter(adapter);
}
@Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
checkPreferences();
loadData();
Button backbtn = (Button) findViewById(R.id.backbtn);
//Listening to button event
backbtn.setOnClickListener(new View.OnClickListener() {
public void onClick(View arg0) {
//Starting a new Intent
Intent previousScreen = new Intent(getApplicationContext(), ChooseTeamActivity.class);
ChosenMethod = "null";
SharedPreferences preferences = getSharedPreferences("prefs", Context.MODE_PRIVATE);
SharedPreferences.Editor editor = preferences.edit();
editor.putString("ChosenMethod", ChosenMethod);
editor.commit();
previousScreen.putExtra("FullData", fulldata);
startActivity(previousScreen);
}
});
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.menu, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
if (item.getItemId() == R.id.home) {
startActivity(new Intent(HomeActivity.this, HomeActivity.class));
return(true);
}
if (item.getItemId() == R.id.match) {
startActivity(new Intent(HomeActivity.this, MatchActivity.class));
return(true);
}
if (item.getItemId() == R.id.teams) {
startActivity(new Intent(HomeActivity.this, TeamsActivity.class));
return(true);
}
if (item.getItemId() == R.id.twitter) {
startActivity(new Intent(HomeActivity.this, TwitterActivity.class));
return(true);
}
if (item.getItemId() == R.id.info) {
startActivity(new Intent(HomeActivity.this, InfoActivity.class));
return(true);
}
return(super.onOptionsItemSelected(item));
}
}