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Android Programming
Hands On No. 6 : Data Passing using JSON
Resources
API Code in PHP - showDetails.php
<?php
//0 for record not found
//-1 for Not Get Error
//-2 for Parameter Error
$s2 = array();
class Subject {
public $cno = "";
public $ccode = "";
public $cname = "";
public $cincharge = "";
}
$s = new Subject();
if($_GET)
{
$a = isset($_GET['id'])?$_GET['id']:0;
if($a==0)
{
$con = mysqli_connect("localhost","root","","tybca2018");
if (!$con)
{
echo "Error";
}
$res = mysqli_query($con,"select * from subject where sno='$a'");
$n = mysqli_num_rows($res);
//echo $n;
if($n==0)
{
$s->cno = "0";
$s->ccode = "0";
$s->cname = "0";
$s->cincharge = "0";
$s1 = array('subject' => $s);
array_push($s2,$s1);
}
else
{
while ($row = mysqli_fetch_assoc($res))
{
$s->cno = $row['sid'];
$s->ccode = $row['sno'];
$s->cname = $row['sname'];
$s->cincharge = $row['cincharge'];
$s1 = array('subject' => $s);
array_push($s2,$s1);
}
}
mysqli_close($con);
}
else
{
$s->cno = "-2";
$s->ccode = "-2";
$s->cname = "-2";
$s->cincharge = "-2";
$s1 = array('subject' => $s);
array_push($s2,$s1);
}
}
else
{
$s->cno = "-1";
$s->ccode = "-1";
$s->cname = "-1";
$s->cincharge = "-1";
$s1 = array('subject' => $s);
array_push($s2,$s1);
}
echo json_encode($s1);
?>
Table Schema of subject in MYSQL
CREATE TABLE `subject` (
`sid` bigint(20) UNSIGNED NOT NULL,
`sno` varchar(10) NOT NULL,
`sname` varchar(50) NOT NULL,
`cincharge` varchar(50) NOT NULL
) ENGINE=MyISAM DEFAULT CHARSET=latin1;
INSERT INTO `subject` (`sid`, `sno`, `sname`, `cincharge`) VALUES
(1, 'CA312', 'Andorid', 'Dhaval Mehta'),
(2, 'CA101', 'Web Design', 'Yash Karanke');
ALTER TABLE `subject`
ADD UNIQUE KEY `sid` (`sid`);
ALTER TABLE `subject`
MODIFY `sid` bigint(20) UNSIGNED NOT NULL AUTO_INCREMENT, AUTO_INCREMENT=3;
COMMIT;
Source Code of ActivityMain.java
mport androidx.appcompat.app.AppCompatActivity;
import android.app.AlertDialog;
import android.content.Context;
import android.content.DialogInterface;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import com.android.volley.Request;
import com.android.volley.Response;
import com.android.volley.VolleyError;
import com.android.volley.toolbox.JsonObjectRequest;
import com.android.volley.toolbox.Volley;
import org.json.JSONException;
import org.json.JSONObject;
public class MainActivity extends AppCompatActivity {
Button mButton;
TextView tv1,tv2;
AlertDialog.Builder builder;
String s;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mButton = (Button)findViewById(R.id.load_data);
tv1 = (TextView) findViewById(R.id.txtcname);
final EditText et1 = (EditText) findViewById(R.id.txtcode);
builder = new AlertDialog.Builder(this);
builder.setMessage("Are You Sure to Exit").setTitle("W3TechBlog");
builder.create();
mButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
ConnectivityManager cm = (ConnectivityManager) getApplicationContext().getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo nInfo = cm.getActiveNetworkInfo();
boolean connected = nInfo != null && nInfo.isAvailable() && nInfo.isConnected();
if(connected) {
s = et1.getText().toString().trim();
String url = "https://w3techblog.com/tybca_example/showDetails.php?id=" + s;
JsonObjectRequest jsonRequest = new JsonObjectRequest
(Request.Method.GET, url, null, new Response.Listener() {
@Override
public void onResponse(JSONObject response) {
// the response is already constructed as a JSONObject!
try {
response = response.getJSONObject("subject");
String sname = response.getString("cname"),
cname = response.getString("cincharge");
if (sname.equals("0")) {
tv1.setText("Record Not Found");
} else if (sname.equals("-1")) {
tv1.setText("Not using GET method");
} else if (sname.equals("-2")) {
tv1.setText("Error in Parameter");
} else {
tv1.setText("Course Name " + sname + "\nCourse Incharge Name : " + cname);
}
} catch (JSONException e) {
tv1.setText(e.toString());
System.out.println(e.toString());
}
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
builder.setMessage("Server is not Responding...").setTitle("W3TechBlog");
builder.setPositiveButton("OK", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
}
});
builder.show();
}
});
Volley.newRequestQueue(MainActivity.this).add(jsonRequest);
}
else
{
builder.setMessage("Internet is Off").setTitle("W3TechBlog");
builder.setPositiveButton("OK", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
}
});
builder.show();
}
}
});
}
@Override
public void onBackPressed() {
builder.setMessage("Are You Sure to Exit").setTitle("W3TechBlog");
builder.setPositiveButton("OK", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
System.exit(0);
}
});
builder.setNegativeButton("CANCEL", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
// User cancelled the dialog
}
});
builder.show();
}
}
Add following line in build.gradle of app
implementation 'com.android.volley:volley:1.1.1'
Source Code of activity_main.xml
<TableLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent">
<TableRow android:layout_marginTop="50dp">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_column="1"
android:layout_marginLeft="40dp"
android:text="Course Code"
android:textAppearance="@style/TextAppearance.AppCompat.Body2"
android:textColor="@android:color/holo_blue_light"
android:textSize="25sp" />
<EditText
android:id="@+id/txtcode"
android:layout_width="wrap_content"
android:layout_height="60dp"
android:layout_marginLeft="20dp"
android:width="150dp"
android:ems="20" />
</TableRow>
<TableRow
android:layout_width="fill_parent"
android:layout_height="fill_parent">
<Button
android:id="@+id/load_data"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_column="2"
android:layout_marginLeft="20dp"
android:layout_marginTop="20dp"
android:background="@color/colorAccent"
android:text="Submit"
android:textColor="@android:color/white"
android:textSize="25sp" />
</TableRow>
<TableRow
android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView
android:id="@+id/txtcname"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="40dp"
android:layout_span="2"
android:text="Course Code"
android:textColor="@android:color/holo_blue_light" />
</TableRow>
</TableLayout>
Add following code in AndroidManifest.xml File
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />