This article shows how to obtain other application data and the application process of runtime permission through an example of obtaining all contacts.

1. Add the following permissions to AndroidManifest.xml

<uses-permission android:name="android.permission.READ_CONTACTS"></uses-permission>

1. Declare that a listView stores the contact information retrieved; check whether there is a corresponding permission, if not, request the corresponding permission, and there will be a corresponding callback method after the permission is granted.

    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        ListView contractsView = findViewById(R.id.contacts_view);
        adapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, contactsList);
        contactsView.setAdapter(adapter);
        if (ContextCompat.checkSelfPermission(this, Manifest.permission.READ_CONTACTS) !=
                PackageManager.PERMISSION_GRANTED) {
            ActivityCompat.requestPermissions(this,
                    new String[]{Manifest.permission.READ_CONTACTS}, 1);
        } else {
            readContacts();
        }
    }

1. Callback method after authorization.

 @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
        switch (requestCode) {
            case 1:
                if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                    readContacts();
                } else {
                    Toast.makeText(this, "You denied the permission", Toast.LENGTH_SHORT).show();
                }
                break;
            default:
        }
    }

1. Read contacts, use ContentResolver's query() method, pass in uri and other filtering parameters, and return a Cursor object. Traverse the Cursor and put it in the listview.

 private void readContacts() {
        Cursor cursor = null;
        try {
            cursor = getContentResolver().query(ContactsContract.CommonDataKinds.Phone.CONTENT_URI, null, null, null, null);
            if (cursor != null) {
                while (cursor.moveToNext()) {
                    String displatName = cursor.getString(cursor.getColumnIndex(ContactsContract.CommonDataKinds.Phone.DISPLAY_NAME));
                    String number = cursor.getString(cursor.getColumnIndex(ContactsContract.CommonDataKinds.Phone.NUMBER));
                    contactsList.add(displatName + "\n" + number);
                }
                adapter.notifyDataSetChanged();
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if (cursor != null) {
                cursor.close();
            }
        }
    }