从数据库mySQL中检索数据，应用程序已停止（Android studio）

Question

当我想从数据库中检索记录的详细信息时出现问题，当我运行项目时它告诉我项目已停止工作。错误在这一行JSONObject json = jParser.makeHttpRequest（url_Edu_details，＆＃34; GET＆＃34;，params）;

package com.example.dell.adegma;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import org.apache.http.NameValuePair;
import org.apache.http.message.BasicNameValuePair;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import android.app.Activity;
import android.app.ListActivity;
import android.app.ProgressDialog;
import android.content.Intent;
import android.os.AsyncTask;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

public class GetEduDetails extends GetRecords {

TextView txtName;

String ID;


private ProgressDialog pDialog;

JSONParser jParser = new JSONParser();

private static final String url_Edu_details= "http://10.10.88.105/app_connect/get_school_details.php";

private static final String TAG_SUCCESS = "success";
private static final String TAG_EDUCATION = "education";
private static final String TAG_ID = "ID";
private static final String TAG_SNAME = "SName";
private static final String TAG_TYPE = "Type";
private static final String TAG_GENDER = "Gender";
private static final String TAG_GRADES = "Grades";
private static final String TAG_LOCATION = "Location";
private static final String TAG_TELEPHONE = "Telephone";
private static final String TAG_CURRICULUM = "Curriculum";
private static final String TAG_EMAIL = "Email";
private static final String TAG_FEES = "Fees";


@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.content_get_records);

    Intent i = getIntent();

    ID = i.getStringExtra(ID);

    new loadEduDetails().execute();

}

/**
 * Background Async Task to Get complete school details
 * */
class loadEduDetails extends AsyncTask<String, String, String> {

    /* Before starting background thread Show Progress Dialog*/
    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        pDialog = new ProgressDialog(GetEduDetails.this);
        pDialog.setMessage("Loading school details. Please wait...");
        pDialog.setIndeterminate(false);
        pDialog.setCancelable(true);
        pDialog.show();
    }

    /**
     * Getting school details in background thread
     * */
    protected String doInBackground(String... params) {

        // updating UI from Background Thread
        runOnUiThread(new Runnable() {
            public void run() {
                // Check for success tag
                int success;
                try {
                    // Building Parameters
                    HashMap<String, String> params = new HashMap<>();
                    params.put(TAG_ID,ID);



                    // getting school details by making HTTP request
                    // Note that school details url will use GET request
                    JSONObject json = jParser.makeHttpRequest(url_Edu_details, "GET", params);

                    // check your log for json response
                    Log.d("Single school Details", json.toString());

                    // json success tag
                    success = json.getInt(TAG_SUCCESS);
                    if (success == 1) {
                        // successfully received school details
                        JSONArray educationObj = json.getJSONArray(TAG_EDUCATION); // JSON Array

                        // get first school object from JSON Array
                        JSONObject education = educationObj.getJSONObject(0);

                        // school with this id found
                        // Edit Text
                        txtName = (TextView) findViewById(R.id.SchoolName);


                        // display data in TextView
                        txtName.setText(education.getString(TAG_SNAME));


                    }else{
                        // school with id not found
                    }
                } catch (JSONException e) {
                    e.printStackTrace();
                }
            }
        });

        return null;
    }

    /**
     * After completing background task Dismiss the progress dialog
     * **/
    protected void onPostExecute(String file_url) {
        // dismiss the dialog once got all details
        pDialog.dismiss();
    }
}

}

这是logcat： -

03-31 15:18:17.144 6012-6012/com.example.dell.adegma D/AndroidRuntime: Shutting down VM
03-31 15:18:17.146 6012-6012/com.example.dell.adegma E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.dell.adegma, PID: 6012
java.lang.NullPointerException: Attempt to invoke virtual method 'int     java.lang.String.length()' on a null object reference
at libcore.net.UriCodec.encode(UriCodec.java:132)
at java.net.URLEncoder.encode(URLEncoder.java:57)
at com.example.dell.adegma.JSONParser.makeHttpRequest(JSONParser.java:38)
at com.example.dell.adegma.GetEduDetails$loadEduDetails$1.run(GetEduDetails.java:107)
at android.os.Handler.handleCallback(Handler.java:815)
at android.os.Handler.dispatchMessage(Handler.java:104)
at android.os.Looper.loop(Looper.java:194)
at android.app.ActivityThread.main(ActivityThread.java:5651)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:959)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:754)