Ich möchte Hilfe beim Erstellen einer PHP-Datei für die Datenbank, um sie an meinen Server anzuhängen und zu verwenden es für json parsing.also weiß ich nicht, wie man ein spezifisches json in Bezug auf eine php Akte verursacht. Ich möchte nur eine App erstellen, um Textdaten vom Server abzurufen. ** Jede Informationen darüber, wie ein PHP-n seine json schaffen wird sehr hilfreich sein. **NullPointerException: Versuch, die virtuelle Methode 'org.json.JSONObject org.json.JSONArray.getJSONObject (int)' für eine Nullobjekt-Referenz aufzurufen
Das ist mein MainActivity.java Klasse
public class MainActivity extends ActionBarActivity implements View.OnClickListener {
private TextView textViewJSON;
private Button buttonGet;
private Button buttonParse;
public static final String MY_JSON ="MY_JSON";
private static final String JSON_URL = "\n" +
"http://file-manager.000webhost.com/file-manager/index.php";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
textViewJSON = (TextView) findViewById(R.id.textViewJSON);
textViewJSON.setMovementMethod(new ScrollingMovementMethod());
buttonGet = (Button) findViewById(R.id.buttonGet);
buttonParse = (Button) findViewById(R.id.buttonParse);
buttonGet.setOnClickListener(this);
buttonParse.setOnClickListener(this);
}
@Override
public void onClick(View v) {
if(v==buttonGet){
getJSON(JSON_URL);
}
if(v==buttonParse){
showParseActivity();
}
}
private void showParseActivity() {
Intent intent = new Intent(this, ParseJSON.class);
intent.putExtra(MY_JSON,textViewJSON.getText().toString());
startActivity(intent);
}
private void getJSON(String url) {
class GetJSON extends AsyncTask<String, Void, String>{
ProgressDialog loading;
@Override
protected void onPreExecute() {
super.onPreExecute();
loading = ProgressDialog.show(MainActivity.this, "Please Wait...",null,true,true);
}
@Override
protected String doInBackground(String... params) {
String uri = params[0];
BufferedReader bufferedReader = null;
try {
URL url = new URL(uri);
HttpURLConnection con = (HttpURLConnection) url.openConnection();
StringBuilder sb = new StringBuilder();
bufferedReader = new BufferedReader(new InputStreamReader(con.getInputStream()));
String json;
while((json = bufferedReader.readLine())!= null){
sb.append(json+"\n");
}
return sb.toString().trim();
}catch(Exception e){
return null;
}
}
@Override
protected void onPostExecute(String s) {
super.onPostExecute(s);
loading.dismiss();
textViewJSON.setText(s);
}
}
GetJSON gj = new GetJSON();
gj.execute(url);
}
}
Das ist mein ParserJson.java Klasse
public class ParseJSON extends ActionBarActivity implements View.OnClickListener{
private String myJSONString;
private static final String JSON_ARRAY ="result";
private static final String ID = "id";
private static final String USERNAME= "name";
private JSONArray users = null;
private int TRACK = 0;
private EditText editTextId;
private EditText editTextUserName;
private EditText editTextPassword;
Button btnPrev;
Button btnNext;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_parse_json);
Intent intent = getIntent();
myJSONString = intent.getStringExtra(MainActivity.MY_JSON);
editTextId = (EditText) findViewById(R.id.editTextID);
editTextUserName = (EditText) findViewById(R.id.editTextUsername);
editTextPassword = (EditText) findViewById(R.id.editTextPassword);
btnPrev = (Button) findViewById(R.id.buttonPrev);
btnNext = (Button) findViewById(R.id.buttonNext);
btnPrev.setOnClickListener(this);
btnNext.setOnClickListener(this);
extractJSON();
showData();
}
private void extractJSON(){
try {
JSONObject jsonObject = new JSONObject(myJSONString);
//users =new JSONArray(JSON_ARRAY);
users = jsonObject.getJSONArray(JSON_ARRAY);
// JSONObject jsonObject =users.getJSONObject(0);
} catch (JSONException e) {
e.printStackTrace();
}
}
private void moveNext(){
if(TRACK<users.length()){
TRACK++;
}
showData();
}
private void movePrev(){
if(TRACK>0){
TRACK--;
}
showData();
}
private void showData(){
try {
JSONObject jsonObject = users.getJSONObject(TRACK);
editTextId.setText(jsonObject.getString(ID));
editTextUserName.setText(jsonObject.getString(USERNAME));
} catch (JSONException e) {
e.printStackTrace();
}
}
@Override
public void onClick(View v) {
if(v == btnNext){
moveNext();
}
if(v == btnPrev){
movePrev();
}
}
}
Dies ist meine PHP-Datei im öffentlichen HTML-Ordner von Dateimanager.Ich weiß auch nicht, wo diese Datei zu speichern, die über meine Datenbank erzählt. Der Name meiner PHP-Datei ist mark42.php aber es spart als index.php.
<?php
define('HOST','mysql9.000webhost.com');
define('USER','**********');
define('PASS','******');
define('DB','a4023522_db');$con = mysqli_connect(HOST,USER,PASS,DB); $sql = "select * from mark42";
$res = mysqli_query($con,$sql);
$result = array();
while($row = mysqli_fetch_array($res)){
array_push($result,array('id'=>$row[0],'name'=>$row[1]));
}
echo json_encode(array("result"=>$result));
mysqli_close($con);
?>
Das ist mein logcat Fehler, Abstürze app, wenn ich drücken Sie die parsejson Taste.
FATAL EXCEPTION: main Process: test.nic.com.nicpro, PID: 6506
java.lang.RuntimeException: Unable to start activity ComponentInfo{test.nic.com.nicpro/test.nic.com.nicpro.ParseJSON}: java.lang.NullPointerException: Attempt to invoke virtual method 'org.json.JSONObject org.json.JSONArray.getJSONObject(int)' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2416)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
at android.app.ActivityThread.-wrap11(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'org.json.JSONObject org.json.JSONArray.getJSONObject(int)' on a null object reference
at test.nic.com.nicpro.ParseJSON.showData(ParseJSON.java:94)
at test.nic.com.nicpro.ParseJSON.onCreate(ParseJSON.java:62)
at android.app.Activity.performCreate(Activity.java:6251)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1107)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2369)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
at android.app.ActivityThread.-wrap11(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
TLDR - Konsolidierung Ihrer Frage bitte – cmorrissey
Können Sie Ihre gepostete Fehlerprotokoll Katze sehen? Bitte teilen Sie auch Ihre JSON-Datei. –
@MdSufiKhan Ich habe alle Java-Klassen gepostet, die ich benutzt habe.Sie finden darin einen Fehler. – 7rocker