Android - startActivity（intent）崩溃应用程序

Question

我正在尝试这样做，以便在按下按钮时此方法启动一个新活动，但应用程序在第二个活动开始之前崩溃。该按钮正确对应方法，新活动列在清单文件中。

MainActivity方法：

public void okay(View view) {

        Intent intent = new Intent(MainActivity.this, DisplayActivity.class);

        boolean dayofweek, season, daystill;
        dayofweek = ((CheckBox) findViewById(R.id.checkBoxDayofweek)).isChecked();
        season = ((CheckBox) findViewById(R.id.checkBoxSeason)).isChecked();
        daystill = ((CheckBox) findViewById(R.id.checkBoxDaystill)).isChecked();

        intent.putExtra(EXTRA_DAYOFWEEK, dayofweek);
        intent.putExtra(EXTRA_SEASON, season);
        intent.putExtra(EXTRA_DAYSTILL, daystill);

        DatePicker datepicker = (DatePicker) findViewById(R.id.datePicker);
        int day, month, year;
        day = datepicker.getDayOfMonth();
        month = datepicker.getMonth();
        year = datepicker.getYear();

        intent.putExtra(EXTRA_DAY, day);
        intent.putExtra(EXTRA_MONTH, month);
        intent.putExtra(EXTRA_YEAR, year);

        startActivity(intent);

    }

DisplayActivity：

public class DisplayActivity extends Activity {
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        Intent intent = getIntent();
        boolean dayofweek = intent.getBooleanExtra(MainActivity.EXTRA_DAYOFWEEK, false);
        boolean season = intent.getBooleanExtra(MainActivity.EXTRA_SEASON, false);
        boolean daystill = intent.getBooleanExtra(MainActivity.EXTRA_DAYSTILL, false);
        int day = intent.getIntExtra(MainActivity.EXTRA_DAY, 0);
        int month = intent.getIntExtra(MainActivity.EXTRA_MONTH, 0);
        int year = intent.getIntExtra(MainActivity.EXTRA_YEAR, 0);

        TextView output = new TextView(this);
        output.setTextSize(30);

        String s = day + "/" + month + "/" + year + "\n";
        if(dayofweek) s += "";

        output.setText(s);
        setContentView(output);

    }
}