Nel codice le parti in azzurro sono quelle relative alla gestione dei permessi mentre quelle in giallo sono per la gestione della creazione del JSON
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<?xml version="1.0" encoding="utf-8"?><manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.example.lucainnocenti.jsontester"> <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" /> <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" /> <application android:allowBackup="true" android:icon="@mipmap/ic_launcher" android:label="@string/app_name" android:roundIcon="@mipmap/ic_launcher_round" android:supportsRtl="true" android:theme="@style/AppTheme"> <activity android:name=".MainActivity"> <intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> </activity> </application> </manifest>
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package com.example.lucainnocenti.jsontester;
import android.Manifest;
import android.content.pm.PackageManager;
import android.os.Environment;
import android.support.v4.app.ActivityCompat;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.JsonWriter;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;
import org.json.JSONException;
import org.json.JSONObject;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.io.UnsupportedEncodingException;
public class MainActivity extends AppCompatActivity {
private int requestCode;
private int grantResults[];
private FileOutputStream out;
private JsonWriter writer;
private File card;
private File file;
@Override protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE}, requestCode);
onRequestPermissionsResult(requestCode, new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE}, grantResults);
Button pulsante =(Button) findViewById(R.id.button);
pulsante.setOnClickListener(new View.OnClickListener() {
@Override public void onClick(View view) {
card = Environment.getExternalStorageDirectory();
file = new File (card.getAbsolutePath(),"dati.json");
try {
out = new FileOutputStream(file);
} catch (FileNotFoundException e) {
e.printStackTrace();
}
try {
writer = new JsonWriter(new OutputStreamWriter(out,"UTF-8"));
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
}
try {
writer.beginObject();
} catch (IOException e) {
e.printStackTrace();
}
try {
writer.name("nome").value("Luca");
writer.name("cognome").value("Innocenti");
} catch (IOException e) {
e.printStackTrace();
}
try {
writer.endObject();
} catch (IOException e) {
e.printStackTrace();
}
try {
writer.close();
} catch (IOException e) {
e.printStackTrace();
}
;
}
});
}
@Override
public void onRequestPermissionsResult(int requestCode, String permissions[], int[] grantResults) {
switch (requestCode) {
case 1: {
// If request is cancelled, the result arrays are empty. if (grantResults.length > 0
&& grantResults[0] == PackageManager.PERMISSION_GRANTED) {
Log.d("permission", "granted");
} else {
Toast.makeText(MainActivity.this, "Permission denied to read your External storage", Toast.LENGTH_SHORT).show();
onDestroy();
}
return;
}
}
}
}
