androidプログラミング

androidプログラミング

2018 Jan. 0６.
2018 Jan. 04.
2018 Jan. 03.
2017 Nov. 23.
2017 Aug. 16.

android, プログラミング, emulator, context, 1行, 読み込み,SD, ファイル読み込み, AlertDialog

preferenceで配列を扱う

https://qiita.com/ueno-yuhei/items/d51c00c5be3971f4cd40

コマンドラインからのemulator起動

$ Android/Sdk/tools/emulator -avd EMULATOR -qemu -m 512 -enable-kvm
EMULATOR: advの名前

context

参考サイト
http://yuki312.blogspot.jp/2012/02/thisgetapplicationcontextactivityapplic.html

1行読み込み

BufferedReader br = null;
try {
    br = new BufferedReader(new FileReader(file));
} catch (FileNotFoundException e) {
    e.printStackTrace();
    if (br != null) try {
        br.close();
    } catch (IOException e1) {
        e1.printStackTrace();
    }
}

String str;
try {
    while((str = br.readLine()) != null){
        Log.v("Read",str);
    }
} catch (IOException e) {
    e.printStackTrace();
} finally {
    if (br != null) {
        try {
            br.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

ＳＤカード上のファイルの読み込み

private String filename = "hoge.txt";
private File directory = Environment.getExternalStorageDirectory();
private String filepath = directory.getAbsolutePath() + "/YourDir/" + filename;

private File file = new File(filepath);

// SDカードマウント状態

final String state = Environment.getExternalStorageState();

if (!state.equals(Environment.MEDIA_MOUNTED)) {

    try {
      throw new IOException("No Mount");
  } catch (IOException e) {
      e.printStackTrace();
  }
}

BufferedReader br = null;
try {
    br = new BufferedReader(new FileReader(file));
} catch (FileNotFoundException e) {
    e.printStackTrace();
    if (br != null) try {
        br.close();
    } catch (IOException e1) {
        e1.printStackTrace();
    }
}

String str;
try {
    while((str = br.readLine()) != null){
        Log.v("Read",str);
    }
} catch (IOException e) {
    e.printStackTrace();
} finally {
    if (br != null) {
        try {
            br.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

AlertDialog　setItemｓ()利用時のコードと挙動

サンプル1　ダイアログにボタンを置かず、アイテムをクリックすれば前画面に戻る

public class MainActivity extends Activity {
  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    final Button btn = (Button)findViewById(R.id.btn);
    btn.setText("Show Dialog");
    btn.setOnClickListener(new View.OnClickListener() {
      public void onClick(View v) {
        final CharSequence[] items = {"car", "train", "byke"};
        new AlertDialog.Builder(MainActivity.this)
          .setTitle("Select tool")
          .setIcon(R.drawable.myIcon)
          .setItems(items, new DialogInterface.OnClickListener() {
            public void onClick(DialogInterface dlg, int which) {
              btn.setText(String.format("%sが選択されました。",items[which]));
            }
          })
          .show();
      }
    });
  }
}

サンプル2　ダイアログにボタンを置かず、アイテムをクリックしても前画面に戻らない

public class MainActivity extends Activity implements DialogInterface.OnClickListener {
    final String[] items = {"car", "train", "byke"};

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        final Button btn = (Button)findViewById(R.id.btn);
        btn.setText("Show Dialog");
        btn.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
                myShowDialog("Not Selected");
            }
        });
    }

    @Override
    public void onClick(DialogInterface dlg, int which) {
        myShowDialog(items[which]);
    }

    public void myShowDialog(final String titleStr) {
        AlertDialog.Builder dialog = new AlertDialog.Builder(this);
        dialog.setTitle(titleStr);
        dialog.setIcon(R.drawable.myIcon);
        dialog.setItems(items, this);
        dialog.show();
    }
}

サンプル3　ダイアログにボタンを置くが、アイテムのクリックでは前画面に戻らない

public class MainActivity extends Activity implements DialogInterface.OnClickListener {
    TextView tv;
    final String[] items = {"car", "train", "byke"};
    final List listItems = Arrays.asList(items); //配列をList型オブジェクトに変換

    @Override
    public void onClick(DialogInterface dlg, int which) {
        Log.v("dialog_which", String.valueOf(which)); // int of order of items
        showDialog(items[which]);
    }

    public void showDialog(final String titleStr) {
        AlertDialog.Builder dialog = new AlertDialog.Builder(this);
        dialog.setTitle(titleStr);
        dialog.setIcon(R.drawable.myIcon);
        dialog.setItems(items, this);

        dialog.setPositiveButton("決 定", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int index) {
                Log.v("dialog_index", String.valueOf(index));  // unexpected int
                tv.setText(titleStr);
            }
        });

        dialog.setNeutralButton("前 へ", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int index) {
                Log.v("dialog_index", String.valueOf(index)); // unexpected int
                int i = listItems.indexOf(titleStr); //list内に引数の要素が存在する最小のインデックスを返す
                int numArray = (i+3-1)%3;
                tv.setText(items[numArray]);
            }
        });

        dialog.setNegativeButton("2つ前へ", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int index) {
                Log.v("dialog_index", String.valueOf(index));  // unexpected int
                int i = listItems.indexOf(titleStr); //list内に引数の要素が存在する最小のインデックスを返す
                int numArray = (i+3-2)%3;
                tv.setText(items[numArray]);
            }
        });
        dialog.show();
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        tv = ((TextView)findViewById(R.id.tv));
        findViewById(R.id.btn).setOnClickListener(new View.OnClickListener(){
            @Override
            public void onClick(View v) {
                showDialog("");
            }
        });
    }
}