E/AndroidRuntime: FATAL EXCEPTION: main
                                                                                  Process: com.example.raahulanand.samplecode, PID: 2819
                                                                                  java.lang.NullPointerException: Attempt to invoke virtual method 'int java.lang.String.length()' on a null object reference
                                                                                      at org.json.JSONTokener.nextCleanInternal(JSONTokener.java:116)
                                                                                      at org.json.JSONTokener.nextValue(JSONTokener.java:94)
                                                                                      at org.json.JSONObject.<init>(JSONObject.java:156)
                                                                                      at org.json.JSONObject.<init>(JSONObject.java:173)
                                                                                      at com.example.raahulanand.samplecode.Main2Activity.insert(Main2Activity.java:99)
                                                                                      at com.example.raahulanand.samplecode.Main2Activity$1.onClick(Main2Activity.java:46)
                                                                                      at android.view.View.performClick(View.java:5198)
                                                                                      at android.view.View$PerformClick.run(View.java:21147)
                                                                                      at android.os.Handler.handleCallback(Handler.java:739)
                                                                                      at android.os.Handler.dispatchMessage(Handler.java:95)
                                                                                      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)

public class Main2Activity extends AppCompatActivity {
    EditText ipusername,ippassword,ipname,ipdept;
    Button btnreg;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main2);


        getSupportActionBar().setDisplayHomeAsUpEnabled(true);
        ipusername = (EditText)findViewById(R.id.editText);
        ippassword = (EditText)findViewById(R.id.editText2);
        ipname = (EditText)findViewById(R.id.editText3);
        ipdept = (EditText)findViewById(R.id.editText4);
        btnreg = (Button)findViewById(R.id.button2);
        btnreg.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                insert();
            }
        });
    }
    public void insert()
    {
        String result1 = null;
        InputStream is = null;
        String username = ipusername.getText().toString();
        String password = ippassword.getText().toString();
        String name = ipname.getText().toString();
        String dept = ipdept.getText().toString();
        ArrayList<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>();
        nameValuePairs.add(new BasicNameValuePair("username", username));
        nameValuePairs.add(new BasicNameValuePair("password",password));
        nameValuePairs.add(new BasicNameValuePair("name",name));
        nameValuePairs.add(new BasicNameValuePair("dept",dept));
        try
        {
            HttpClient httpclient = new DefaultHttpClient();
            HttpPost httppost = new HttpPost("http://10.0.2.2/markolepsy/android_connect/create_fac.php");
            httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
            HttpResponse response = httpclient.execute(httppost);
            HttpEntity entity = response.getEntity();
            is = entity.getContent();

            Log.e("log_tag", "connection success ");
        }
        catch(Exception e)
        {
            Log.e("log_tag", "Error in http connection "+e.toString());
            Toast.makeText(getApplicationContext(), "Connection fail", Toast.LENGTH_SHORT).show();

        }
        try
        {
            BufferedReader reader = new BufferedReader(new InputStreamReader(is,"iso-8859-1"),8);
            StringBuilder sb = new StringBuilder();
            String line = null;
            while ((line = reader.readLine()) != null)
            {
                sb.append(line + "n");
            }
            is.close();

            result1=sb.toString();
        }
        catch(Exception e)
        {
            Log.e("log_tag", "Error converting result "+e.toString());
        }
        try
        {
            JSONObject obj = new JSONObject(result1);
            String w= obj.getString("re");
            Toast.makeText(getApplicationContext(), w, Toast.LENGTH_SHORT).show();
        }
        catch(JSONException e)
        {
            Log.e("log_tag", "Error parsing data " + e.toString());
            Toast.makeText(getApplicationContext(), "JsonArray fail", Toast.LENGTH_SHORT).show();
        }
    }

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.example.raahulanand.samplecode.Main2Activity">

    <EditText
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/editText"
        android:layout_alignParentTop="true"
        android:layout_marginTop="56dp"
        android:layout_alignParentEnd="true"
        android:layout_alignParentStart="true"
        android:hint="NAME" />

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="INSERT"
        android:id="@+id/button2"
        android:layout_alignParentBottom="true"
        android:layout_centerHorizontal="true" />

    <EditText
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/editText2"
        android:layout_below="@+id/editText"
        android:layout_alignParentStart="true"
        android:layout_alignParentEnd="true"
        android:hint="password" />

    <EditText
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/editText3"
        android:layout_below="@+id/editText2"
        android:layout_alignParentEnd="true"
        android:layout_alignParentStart="true"
        android:hint="name" />

    <EditText
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/editText4"
        android:layout_centerVertical="true"
        android:layout_alignParentStart="true"
        android:layout_alignParentEnd="true" />
</RelativeLayout>