如何添加自动刷新在下面的代码安卓API服务

Question

如何设置5秒的后台刷新间隔。根据我的代码，当我发布新名称时，它不会显示，因此当我重新打开应用程序时，它会显示，所以我需要自动刷新。

我应该更改什么或添加什么。

MainActivity
public class MainActivity extends AppCompatActivity {
ListView listView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
listView = (ListView) findViewById(R.id.listViewHeroes);
//calling the method to display the heroes
getHeroes();
}
private void getHeroes() {
Retrofit retrofit = new Retrofit.Builder()
.baseUrl(Api.BASE_URL)
.addConverterFactory(GsonConverterFactory.create()) //Here we are using the GsonConverterFactory to directly convert json data to object
.build();
Api api = retrofit.create(Api.class);
Call<List<Hero>> call = api.getHeroes();
call.enqueue(new Callback<List<Hero>>() {
@Override
public void onResponse(Call<List<Hero>> call, Response<List<Hero>> response) {
List<Hero> heroList = response.body();
//Creating an String array for the ListView
String[] heroes = new String[heroList.size()];
//looping through all the heroes and inserting the names inside the string array
for (int i = 0; i < heroList.size(); i++) {
heroes[i] = heroList.get(i).getName();
}

//displaying the string array into listview
listView.setAdapter(new ArrayAdapter<String>(getApplicationContext(), android.R.layout.simple_list_item_1, heroes));
}
@Override
public void onFailure(Call<List<Hero>> call, Throwable t) {
Toast.makeText(getApplicationContext(), t.getMessage(), Toast.LENGTH_SHORT).show();
}
});
}
}

Answer 1

看到变化，基本上使用Handler作为周期性的东西-

public class MainActivity extends AppCompatActivity {
ListView listView;
Handler handler = new Handler();
int apiDelayed = 5*1000; //1 second=1000 milisecond, 5*1000=5seconds
Runnable runnable;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
listView = (ListView) findViewById(R.id.listViewHeroes);
//calling the method to display the heroes
getHeroes();
}
@Override
protected void onResume() {
super.onResume();
handler.postDelayed( runnable = new Runnable() {
public void run() {
//do your function;
getHeroes();
handler.postDelayed(runnable, apiDelayed);
}
}, apiDelayed); // so basically after your getHeroes(), from next time it will be 5 sec repeated
}
@Override
protected void onPause() {
super.onPause();
handler.removeCallbacks(runnable); //stop handler when activity not visible
}
private void getHeroes() {
Retrofit retrofit = new Retrofit.Builder()
.baseUrl(Api.BASE_URL)
.addConverterFactory(GsonConverterFactory.create()) //Here we are using the GsonConverterFactory to directly convert json data to object
.build();
Api api = retrofit.create(Api.class);
Call<List<Hero>> call = api.getHeroes();
call.enqueue(new Callback<List<Hero>>() {
@Override
public void onResponse(Call<List<Hero>> call, Response<List<Hero>> response) {
List<Hero> heroList = response.body();
//Creating an String array for the ListView
String[] heroes = new String[heroList.size()];
//looping through all the heroes and inserting the names inside the string array
for (int i = 0; i < heroList.size(); i++) {
heroes[i] = heroList.get(i).getName();
}

//displaying the string array into listview
listView.setAdapter(new ArrayAdapter<String>(getApplicationContext(), android.R.layout.simple_list_item_1, heroes));
}
@Override
public void onFailure(Call<List<Hero>> call, Throwable t) {
Toast.makeText(getApplicationContext(), t.getMessage(), Toast.LENGTH_SHORT).show();
}
});
}
}