按下按钮时不弹出日期

Question

我是 android 编码新手。我正在尝试通过单击按钮来设置日期。我已经阅读并尝试了其他成员在这里发布的许多方法，但是每当我点击按钮时，什么都没有发生。我的代码有什么问题吗？

public class Date extends Activity {

private TextView tvDisplayDate;
private Button btnDate;

private int year;
private int month;
private int day;

static final int DATE_DIALOG_ID = 999;

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

    setCurrentDateOnView();
    addListenerOnButton();

}

// display current date
public void setCurrentDateOnView() {

    tvDisplayDate = (TextView) findViewById(R.id.date);
    //dpResult = (DatePicker) findViewById(R.id.dpResult);

    final Calendar c = Calendar.getInstance();
    year = c.get(Calendar.YEAR);
    month = c.get(Calendar.MONTH);
    day = c.get(Calendar.DAY_OF_MONTH);

    // set current date into textview
    tvDisplayDate.setText(new StringBuilder()
        // Month is 0 based, just add 1
        .append(month + 1).append("-").append(day).append("-")
        .append(year).append(" "));



}

public void addListenerOnButton() {

    btnDate = (Button) findViewById(R.id.SetDate);

    btnDate.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View v) {

            showDialog(DATE_DIALOG_ID);

        }

    });

}

@Override
protected Dialog onCreateDialog(int id) {
    switch (id) {
    case DATE_DIALOG_ID:
       // set date picker as current date
       return new DatePickerDialog(this, datePickerListener, 
                     year, month,day);
    }
    return null;
}

private DatePickerDialog.OnDateSetListener datePickerListener 
            = new DatePickerDialog.OnDateSetListener() {

    // when dialog box is closed, below method will be called.
    public void onDateSet(DatePicker view, int selectedYear,
            int selectedMonth, int selectedDay) {
        year = selectedYear;
        month = selectedMonth;
        day = selectedDay;

        // set selected date into textview
        tvDisplayDate.setText(new StringBuilder().append(month + 1)
           .append("-").append(day).append("-").append(year)
           .append(" "));


    }
};

}

Answer 1

您确实可以使用日历 class 但是我宁愿保持简短和简单，但结果相同。我将向您展示我在其他人的博客上使用并找到的替代方案。

// Formats are everywhere on the internet.
DateFormat dateFormat = new SimpleDateFormat("MM-dd-yyyy ");
Calendar cal = Calendar.getInstance();
String output = dateFormat.format(cal.getTime());
System.out.println(output);

只需将 System.out.print 方法更改为视图的 setText。

来源：http://www.mkyong.com/java/java-how-to-get-current-date-time-date-and-calender/

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