package goodroid.sample.date;

import goodroid.sample.date.R;

import java.util.Calendar;

import android.app.Activity;
import android.os.Bundle;
import android.widget.TextView;

public class DateActivity extends Activity {
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        Calendar calendar = Calendar.getInstance();

        // 年月日を取得
        int year = calendar.get(Calendar.YEAR);
        int month = calendar.get(Calendar.MONTH);
        int day = calendar.get(Calendar.DAY_OF_MONTH);

        // 曜日を取得
        String weekday = null;
        switch(calendar.get(Calendar.DAY_OF_WEEK)){
        case 1:
        	weekday = "日";
        	break;
        case 2:
        	weekday = "月";
        	break;
        case 3:
        	weekday = "火";
        	break;
        case 4:
        	weekday = "水";
        	break;
        case 5:
        	weekday = "木";
        	break;
        case 6:
        	weekday = "金";
        	break;
        case 7:
        	weekday = "土";
        	break;
        }

        // 何週目かを取得する（月、年）
        int week1 = calendar.get(Calendar.WEEK_OF_MONTH);
        int week2 = calendar.get(Calendar.WEEK_OF_YEAR);

        TextView tv1 = (TextView)findViewById(R.id.date);
        tv1.setText(year + "年" + month + "月" + day + "日 (" + weekday + ")");

        TextView tv2 = (TextView)findViewById(R.id.weekOfMonth);
        tv2.setText("月の第" + week1 + "週目");

        TextView tv3 = (TextView)findViewById(R.id.weekOfYear);
        tv3.setText("年の第" + week2 + "週目");

    }
}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >

    <TextView
        android:id="@+id/date"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content" />
    <TextView
        android:id="@+id/weekOfMonth"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content" />
    <TextView
        android:id="@+id/weekOfYear"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content" />

</LinearLayout>