Please enable desugaring by adding the following to build.gradle 오류

안드로이드 스튜디오에서 빌드시에 오류가 났다.
오류 메세지는 Please enable desugaring by adding the following to build.gradle 이것.
원인을 살펴보니 안드로이드 스튜디오에서 Java 8 을 사용하도록 설정하지 않아서였다.

프로젝트 우클릭 -> Open Module Settion (F4) 메뉴
-> Modules 에서 Source와 Target Compatibility 를 1.8 로 변경해주니 해결~

[Android] Glide

안드로이드용 이미지 로딩 라이브러리.

 

https://futurestud.io/blog/glide-getting-startedhttps://github.com/bumptech/glide
http://dktfrmaster.blogspot.kr/2016/09/glide.html
http://itpangpang.xyz/243

 

[Android] Retrofit

HTTP REST API 구현을 위한 라이브러리.

GET, POST, PUT, DELETED 전달  ->  xml, json, text, rss  등으로 응답을 받을 수 있음

 

 

http://thdev.tech/androiddev/2016/11/13/Android-Retrofit-Intro.html

[Android] Gallery Refresh after Kitkat (ver. 4.4)

안드로이드 킷캣 (4.4) 이후 갤러리 갱신 하는 방법이 변경되었다고 합니다.

이전에는 Media Mount 를 이용해서 전체적으로 갱신을 했었는데 배터리 소모가 심한 이슈가 있었다네요

이후에는 아래 코드를 사용하시면 됩니다.

원문 : http://stackoverflow.com/questions/4646913/android-how-to-use-mediascannerconnection-scanfile

import java.io.File;
import android.content.Context;
import android.media.MediaScannerConnection;
import android.media.MediaScannerConnection.MediaScannerConnectionClient;
import android.net.Uri;

public class SingleMediaScanner implements MediaScannerConnectionClient {

private MediaScannerConnection mMs;
private File mFile;

public SingleMediaScanner(Context context, File f) {
    mFile = f;
    mMs = new MediaScannerConnection(context, this);
    mMs.connect();
}

@Override
public void onMediaScannerConnected() {
    mMs.scanFile(mFile.getAbsolutePath(), null);
}

@Override
public void onScanCompleted(String path, Uri uri) {
    mMs.disconnect();
}

}

간단하게는 이 함수만 써도 될 것 같네요~

private void scanFile(String path) {

        MediaScannerConnection.scanFile(MainActivity.this,
                new String[] { path }, null,
                new MediaScannerConnection.OnScanCompletedListener() {

                    public void onScanCompleted(String path, Uri uri) {
                        Log.i("TAG", "Finished scanning " + path);
                    }
                });
    }

Android – BLE Scan Example

package com.example.android.bluetoothlegatt;

import android.app.Activity;
import android.app.ListActivity;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.bluetooth.BluetoothManager;
import android.content.Context;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.os.Bundle;
import android.os.Handler;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;
import java.util.ArrayList;

public class DeviceScanActivity extends ListActivity {
private LeDeviceListAdapter mLeDeviceListAdapter;
private BluetoothAdapter mBluetoothAdapter;
private boolean mScanning;
private Handler mHandler;

private static final int REQUEST_ENABLE_BT = 1;
// Stops scanning after 10 seconds.
private static final long SCAN_PERIOD = 10000;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    getActionBar().setTitle(R.string.title_devices);
    mHandler = new Handler();

    // Use this check to determine whether BLE is supported on the device.  Then you can
    // selectively disable BLE-related features.
    if (!getPackageManager().hasSystemFeature(PackageManager.FEATURE_BLUETOOTH_LE)) {
        Toast.makeText(this, R.string.ble_not_supported, Toast.LENGTH_SHORT).show();
        finish();
    }
    // Initializes a Bluetooth adapter.  For API level 18 and above, get a reference to
    // BluetoothAdapter through BluetoothManager.
    final BluetoothManager bluetoothManager =
            (BluetoothManager) getSystemService(Context.BLUETOOTH_SERVICE);
    mBluetoothAdapter = bluetoothManager.getAdapter();
    // Checks if Bluetooth is supported on the device.
    if (mBluetoothAdapter == null) {
        Toast.makeText(this, R.string.error_bluetooth_not_supported, Toast.LENGTH_SHORT).show();
        finish();
        return;
    }
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    getMenuInflater().inflate(R.menu.main, menu);
    if (!mScanning) {
        menu.findItem(R.id.menu_stop).setVisible(false);
        menu.findItem(R.id.menu_scan).setVisible(true);
        menu.findItem(R.id.menu_refresh).setActionView(null);
    } else {
        menu.findItem(R.id.menu_stop).setVisible(true);
        menu.findItem(R.id.menu_scan).setVisible(false);
        menu.findItem(R.id.menu_refresh).setActionView(
                R.layout.actionbar_indeterminate_progress);
    }
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    switch (item.getItemId()) {
        case R.id.menu_scan:
            mLeDeviceListAdapter.clear();
            scanLeDevice(true);
            break;
        case R.id.menu_stop:
            scanLeDevice(false);
            break;
    }
    return true;
}

@Override
protected void onResume() {
    super.onResume();
    // Ensures Bluetooth is enabled on the device.  If Bluetooth is not currently enabled,
    // fire an intent to display a dialog asking the user to grant permission to enable it.
    if (!mBluetoothAdapter.isEnabled()) {
        if (!mBluetoothAdapter.isEnabled()) {
            Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
            startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT);
        }
    }
    // Initializes list view adapter.
    mLeDeviceListAdapter = new LeDeviceListAdapter();
    setListAdapter(mLeDeviceListAdapter);
    scanLeDevice(true);
}

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    // User chose not to enable Bluetooth.
    if (requestCode == REQUEST_ENABLE_BT && resultCode == Activity.RESULT_CANCELED) {
        finish();
        return;
    }
    super.onActivityResult(requestCode, resultCode, data);
}

@Override
protected void onPause() {
    super.onPause();
    scanLeDevice(false);
    mLeDeviceListAdapter.clear();
}

private void scanLeDevice(final boolean enable) {
    if (enable) {
        // Stops scanning after a pre-defined scan period.
        mHandler.postDelayed(new Runnable() {
            @Override
            public void run() {
                mScanning = false;
                mBluetoothAdapter.stopLeScan(mLeScanCallback);
                invalidateOptionsMenu();
            }
        }, SCAN_PERIOD);
        mScanning = true;
        mBluetoothAdapter.startLeScan(mLeScanCallback);
    } else {
        mScanning = false;
        mBluetoothAdapter.stopLeScan(mLeScanCallback);
    }
    invalidateOptionsMenu();
}

// Adapter for holding devices found through scanning.
private class LeDeviceListAdapter extends BaseAdapter {
    private ArrayList<BluetoothDevice> mLeDevices;
    private LayoutInflater mInflator;

    public LeDeviceListAdapter() {
        super();
        mLeDevices = new ArrayList<BluetoothDevice>();
        mInflator = DeviceScanActivity.this.getLayoutInflater();
    }

    public void addDevice(BluetoothDevice device) {
        if(!mLeDevices.contains(device)) {
            mLeDevices.add(device);
        }
    }

    public BluetoothDevice getDevice(int position) {
        return mLeDevices.get(position);
    }

    public void clear() {
        mLeDevices.clear();
    }

    @Override
    public int getCount() {
        return mLeDevices.size();
    }

    @Override
    public Object getItem(int i) {
        return mLeDevices.get(i);
    }

    @Override
    public long getItemId(int i) {
        return i;
    }

    @Override
    public View getView(int i, View view, ViewGroup viewGroup) {
        ViewHolder viewHolder;
        // General ListView optimization code.
        if (view == null) {
            view = mInflator.inflate(R.layout.listitem_device, null);
            viewHolder = new ViewHolder();
            viewHolder.deviceAddress = (TextView) view.findViewById(R.id.device_address);
            viewHolder.deviceName = (TextView) view.findViewById(R.id.device_name);
            view.setTag(viewHolder);
        } else {
            viewHolder = (ViewHolder) view.getTag();
        }

        BluetoothDevice device = mLeDevices.get(i);
        final String deviceName = device.getName();
        if (deviceName != null && deviceName.length() > 0)
            viewHolder.deviceName.setText(deviceName);
        else
            viewHolder.deviceName.setText(R.string.unknown_device);
        viewHolder.deviceAddress.setText(device.getAddress());

        return view;
    }
}

// Device scan callback.
private BluetoothAdapter.LeScanCallback mLeScanCallback =
        new BluetoothAdapter.LeScanCallback() {

    @Override
    public void onLeScan(final BluetoothDevice device, int rssi, byte[] scanRecord) {
        runOnUiThread(new Runnable() {
            @Override
            public void run() {
                mLeDeviceListAdapter.addDevice(device);
                mLeDeviceListAdapter.notifyDataSetChanged();
            }
        });
    }
};

static class ViewHolder {
    TextView deviceName;
    TextView deviceAddress;
}

http://android-er.blogspot.kr/2011/05/scan-bluetooth-devices.html

안드로이드 디자인 가이드

2013.7.16 일부 내용 수정합니다.
: px * 1.5 를 사용하는 이유에 대해 좀 더 보충했습니다 :)

안드로이드 디자인 방법에 대해 설명해 달라던 디자이너에게 보냈던 메일입니다.

안드로이드 개발자라면 다들 아는 사항이지만 의외로 모르는 디자이너들이 많더군요 ..-_-

모바일앱 디자인 하는 디자이너라면 좀 공부해도 괜찮을텐데..라고 푸념해 봅니다..;;
여튼 참고하셔서 디자이너와 커뮤니케이션 할 때 이용하시면 좋겠네요;;

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