如何从 JSONArray 获取 JSONObject?

Question

尝试从 json 数组获取 json 对象时遇到问题。捕获的错误表明JSONArray无法转换为JSONObject。有效地可以从Web服务获取JSON响应，但我不知道如何将数组转换为对象

错误信息

org.json.JSONException: Value [{"codaspirante":"1","nombre":"Saul","apellido":"Goodman","mail":"[e-mail]","telefono":"012034948123","codusuario":"0"},{"codaspirante":"2","nombre":"Lalo","apellido":"Salamanca","mail":"[e-mail]","telefono":"12351233","codusuario":"10"},{"codaspirante":"3","nombre":"Walter","apellido":"White","mail":"[e-mail]","telefono":"54843439","codusuario":"10"},{"codaspirante":"4","nombre":"Gustavo","apellido":"Frings","mail":"[e-mail]","telefono":"845738848434","codusuario":"10"}] at 0 of type org.json.JSONArray cannot be converted to JSONObject

方法：

private void buscarCandidatos_Serivicio(String URL){
JsonArrayRequest jsonArrayRequest = new JsonArrayRequest(Request.Method.POST, URL, null, new Response.Listener<JSONArray>() {
@Override
public void onResponse(JSONArray response) {
try {
for (int i = 0; i < response.length(); i++) {
JSONObject candidato = response.getJSONObject(i);
Candidato c = new Candidato(
candidato.getInt("codaspirante"),
candidato.getString("nombre"),
candidato.getString("apellido"),
candidato.getString("mail"),
candidato.getString("telefono"),
candidato.getInt("codusuario")
);
listaCandidatos.add(c);
}
} catch (JSONException e) {
Toast.makeText(getApplicationContext(), e.getMessage().toString(), Toast.LENGTH_SHORT).show();
}
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
Toast.makeText(getApplicationContext(), error.getMessage(), Toast.LENGTH_SHORT).show();
}
}
);
RequestQueue rq= Volley.newRequestQueue(this);
rq.add(jsonArrayRequest);
}

Answer 1

错误是因为 response.getJSONObject(0( 返回的是 JSONArray 而不是 JSONObject。

我猜你想从那个数组中获取数据。 在你的On response方法中，你应该添加response=response.getJSONArray(0(。

public void onResponse(JSONArray response) {
try {
response = response.getJSONArray(0);
for (int i = 0; i < response.length(); i++) {        

这应该可以解决您的问题。

Answer 2

val stringRequest = object : StringRequest(
Request.Method.POST, Config."your URL",
Response.Listener<String> { response ->
try {
val obj = JSONObject(response)
if (!obj.getBoolean("error")) {
val userssListArray = obj.getJSONArray("arrayname")
for (i in 0 until userssListArray.length()) {
var usersObj = userssListArray.getJSONObject(i)
}

} else {
if (obj.getString("message") == "Your login expired please re login") {
val intent = Intent(this, LoginActivity::class.java)
startActivity(intent)
finish()
}
}
} catch (e: JSONException) {
e.printStackTrace()
}
},
Response.ErrorListener {
Toast.makeText(this, "Network Error Try Again...", Toast.LENGTH_LONG).show()
}) {
@Throws(AuthFailureError::class)
override fun getParams(): Map<String, String> {
val params = HashMap<String, String>()
return params
}
}
stringRequest.retryPolicy = DefaultRetryPolicy(
15000,
DefaultRetryPolicy.DEFAULT_MAX_RETRIES,
DefaultRetryPolicy.DEFAULT_BACKOFF_MULT)
//adding request to queue
VolleySingleton.instance?.addToRequestQueue(stringRequest)

你可以像这样使用凌空抽射