Question

我有此代码，我尝试使用Android Studio从JSON脚本获取PHP代码，然后获取图片网址和名称以绘制RecycleView有一些列表，并填充它...我总是从NullPointerException JsonArrayRequest方法接收JSON_DATA_WEB_CALL()，我的脑袋会爆炸，我找不到解决方案。 PHP已经过测试，但是它有效，它会正确显示JSON ...任何帮助都会很棒。 Thx提前。这是代码：

访问getdata.php

<?php

    //importing Config file
    include 'include/Config.php';

    // Create connection
    $conn = new mysqli(DB_HOST,DB_USER,DB_PASSWORD,DB_DATABASE);

    if ($conn->connect_error) {
        die("Connection failed: " . $conn->connect_error);
    } 

    $sql ="SELECT * FROM imageplums";
    $result = $conn->query($sql);

    if ($result->num_rows >0) {
        // output data of each row
        while($row[] = $result->fetch_assoc()) {
            $tem = $row;
            $json = json_encode($tem);
        }
    } else {
        echo "0 results";
    }

    echo $json;
    $conn->close();
?>

MainActivity.Java

public class MainActivity extends AppCompatActivity
    implements NavigationView.OnNavigationItemSelectedListener {
    public TextView text;
    public static String MAIL_KEY; 
    RecyclerView recyclerView;
    RecyclerView.Adapter pAdapter;
    RecyclerView.LayoutManager recyclerViewlayoutManager;
    List<PlumImage> plumList;

    String GET_JSON_DATA_HTTP_URL = "http://192.168.1.39:8080/plumster/getdata.php";
    String JSON_IMAGE_TITLE_NAME = "image_title";
    String JSON_IMAGE_URL = "image_url";

    JsonArrayRequest jsonArrayRequest ;
    RequestQueue requestQueue ;

    private SessionManager session;
    private SQLiteHandler db;


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    plumList=new ArrayList<>();

    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) {
            addPlum();
        }
    });

    DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
    ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
            this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
    drawer.setDrawerListener(toggle);
    toggle.syncState();

    NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view); //Creamos Navigationview que corresponde a nav_header_main.xml
    navigationView.setNavigationItemSelectedListener(this);
    View header=navigationView.getHeaderView(0); 
    text=(TextView)header.findViewById(R.id.textViewEmail);

    // SqLite database handler
    db = new SQLiteHandler(getApplicationContext());

    // session manager
    session = new SessionManager(getApplicationContext());


    // Fetching user details from sqlite
    HashMap<String, String> user = db.getUserDetails();

    MAIL_KEY = user.get("email");



    recyclerView=(RecyclerView) findViewById(R.id.recyclerview);
    recyclerView.setHasFixedSize(true);
    recyclerViewlayoutManager = new LinearLayoutManager(this);

    recyclerView.setLayoutManager(recyclerViewlayoutManager);
    //recyclerView.setLayoutManager(new GridLayoutManager(this,2));
    JSON_DATA_WEB_CALL();

}



public void JSON_DATA_WEB_CALL() {
    //Showing a progress dialog
    //final ProgressDialog loading = ProgressDialog.show(this, "Loading data", "Please wait...", false, false);

    JsonArrayRequest jsonArrayRequest = new JsonArrayRequest(GET_JSON_DATA_HTTP_URL,

            new Response.Listener<JSONArray>() {
                @Override
                public void onResponse(JSONArray response) {

                    JSON_PARSE_DATA_AFTER_WEBCALL(response);
                    //loading.dismiss();
                }
            },
            new Response.ErrorListener() {
                @Override
                public void onErrorResponse(VolleyError error) {

                    Toast.makeText(getApplicationContext(),
                            error.networkResponse.toString(), Toast.LENGTH_LONG)
                            .show();
                }
            });

    requestQueue = Volley.newRequestQueue(this);

    requestQueue.add(jsonArrayRequest);
}

//This method will parse json data
public void JSON_PARSE_DATA_AFTER_WEBCALL(JSONArray array){

    for(int i = 0; i<array.length(); i++) {

       PlumImage plumImage = new PlumImage();

        JSONObject json = null;
        try {

            json = array.getJSONObject(i);

            plumImage.setName(json.getString(JSON_IMAGE_TITLE_NAME));

            plumImage.setPhoto(json.getString(JSON_IMAGE_URL));

        } catch (JSONException e) {

            e.printStackTrace();
        }
        plumList.add(plumImage);
    }

    pAdapter = new PlumAdapter(plumList, this);

    recyclerView.setAdapter(pAdapter);
}

Answer 1

它已经解决了，这是一个问题，PHP代码返回null答案。无论如何，谢谢。

填充Recycleview，在JsonArrayRequest中给出null

1 个答案: