如何在 android studio 中返回或重用 Volley 库的响应值？

Question

public class MainActivity extends AppCompatActivity {
    private static final String url = "https://www.googleapis.com/books/v1/volumes?q=android&maxResults=1";
    private static String data ="";
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);


        final StringRequest request = new StringRequest(url, new Response.Listener<String>() {
            @Override
            public void onResponse(String response) {
                data=data + response.substring(0);
                Log.d("CODE1",response);
            }
        }, new Response.ErrorListener() {
            @Override
            public void onErrorResponse(VolleyError error) {
                Toast.makeText(MainActivity.this,"Something went wrong",Toast.LENGTH_SHORT).show();
            }
        });

        RequestQueue queue = Volley.newRequestQueue(this);
        queue.add(request);

        TextView text = (TextView) findViewById(R.id.text_view);
        text.setText(data);


    }

}

I am trying to use the " response " value of onResponse function at the end of the onCreate function. As you can see data is assigned to TEXTVIEW but it is not displayed. How can we use the data in response to pass to other data structure and then use for other work?

Answer 1

use like this:

data=data + response.substring(0);
Log.d("CODE1",response);
text.setText(data);

Because, this line(setText) runs before you send request. You displayed empty data.

Answer 2

Move the setText method into onResponse

Your code will be like this:

       TextView text = (TextView) findViewById(R.id.text_view);
final StringRequest request = new StringRequest(url, new Response.Listener<String>() {
            @Override
            public void onResponse(String response) {
                Log.d("CODE1",response);
                    text.setText(response);
}
        }, new Response.ErrorListener() {
            @Override
            public void onErrorResponse(VolleyError error) {
                Toast.makeText(MainActivity.this,"Something went wrong",Toast.LENGTH_SHORT).show();
            }
        });

        RequestQueue queue = Volley.newRequestQueue(this);
        queue.add(request);