A DatePicker is a widget that allows the user to select a month, day and year. java.lang.Object -> android.view.View -> android.view.ViewGroup -> android.widget.FrameLayout -> android.widget.DatePicker.
Layout file:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="
http://schemas.android.com/apk/res/android"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="vertical">
<TextView android:id="@+id/dateDisplay"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text=""/>
<Button android:id="@+id/pickDate"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Change the date"/>
</LinearLayout>
For the layout, we're using a vertical LinearLayout, with a TextView that will display the date and a Button that will initiate the DatePicker dialog. With this layout, the TextView will sit above the Button. The text value in the TextView is set empty, as it will be filled with the current date when our Activity runs.
Java code, myDatePicker.java:
package com.bogotobogo.myDatePicker;
import java.util.Calendar;
import android.app.Activity;
import android.app.DatePickerDialog;
import android.app.Dialog;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.DatePicker;
import android.widget.TextView;
public class myDatePicker extends Activity {
private TextView mDateDisplay;
private Button mPickDate;
private int mYear;
private int mMonth;
private int mDay;
static final int DATE_DIALOG_ID = 0;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
// capture our View elements
mDateDisplay = (TextView) findViewById(R.id.dateDisplay);
mPickDate = (Button) findViewById(R.id.pickDate);
// add a click listener to the button
mPickDate.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
showDialog(DATE_DIALOG_ID);
}
});
// get the current date
final Calendar c = Calendar.getInstance();
mYear = c.get(Calendar.YEAR);
mMonth = c.get(Calendar.MONTH);
mDay = c.get(Calendar.DAY_OF_MONTH);
// display the current date
updateDisplay();
}
@Override
protected Dialog onCreateDialog(int id) {
switch (id) {
case DATE_DIALOG_ID:
return new DatePickerDialog(this,
mDateSetListener,
mYear, mMonth, mDay);
}
return null;
}
// updates the date we display in the TextView
private void updateDisplay() {
mDateDisplay.setText(
new StringBuilder()
// Month is 0 based so add 1
.append(mMonth + 1).append("-")
.append(mDay).append("-")
.append(mYear).append(" "));
}
// the callback received when the user "sets" the date in the dialog
private DatePickerDialog.OnDateSetListener mDateSetListener =
new DatePickerDialog.OnDateSetListener() {
public void onDateSet(DatePicker view, int year,
int monthOfYear, int dayOfMonth) {
mYear = year;
mMonth = monthOfYear;
mDay = dayOfMonth;
updateDisplay();
}
};
}
Let's look at the code.
We start by instantiating variables for our Views and date fields. The DATE_DIALOG_ID is a static integer that uniquely identifies the Dialog.
In the onCreate() method, we get prepared by setting the layout and capturing the View elements.
We start by instantiating variables for our Views and date fields. The DATE_DIALOG_ID is a static integer that uniquely identifies the Dialog.
In the onCreate() method, we get prepared by setting the layout and capturing the View elements.
mDateDisplay = (TextView) findViewById(R.id.dateDisplay);
mPickDate = (Button) findViewById(R.id.pickDate);
Then we create an on-click listener for the Button, so that when it is clicked it will show our DatePicker dialog. The showDialog() method will pop-up the date picker dialog by calling the onCreateDialog() callback method.
mPickDate.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
showDialog(DATE_DIALOG_ID);
}
});
We then create an instance of Calendar and get the current year, month and day. Finally, we call updateDisplay()�our own method (defined later) that will fill the TextView.
final Calendar c = Calendar.getInstance();
mYear = c.get(Calendar.YEAR);
mMonth = c.get(Calendar.MONTH);
mDay = c.get(Calendar.DAY_OF_MONTH);
updateDisplay();
Next, onCreateDialog() callback method.
This method is called by showDialog() and it is passed the identifier we gave showDialog() and initializes the DatePicker to the date we retrieved from our Calendar instance.
This method is called by showDialog() and it is passed the identifier we gave showDialog() and initializes the DatePicker to the date we retrieved from our Calendar instance.
@Override
protected Dialog onCreateDialog(int id) {
switch (id) {
case DATE_DIALOG_ID:
return new DatePickerDialog(this,
mDateSetListener,
mYear, mMonth, mDay);
}
return null;
}
The updateDisplay() method uses the member date values to write the date to our TextView.
private void updateDisplay() {
mDateDisplay.setText(
new StringBuilder()
// Month is 0 based so add 1
.append(mMonth + 1).append("-")
.append(mDay).append("-")
.append(mYear).append(" "));
}
This OnDateSetListener() method listens for when the user is done setting the date (clicks the "Set" button). At that time, this fires and we update our member fields with the new date defined by the user and update our TextView by callingupdateDisplay().
private DatePickerDialog.OnDateSetListener mDateSetListener =
new DatePickerDialog.OnDateSetListener() {
public void onDateSet(DatePicker view, int year,
int monthOfYear, int dayOfMonth) {
mYear = year;
mMonth = monthOfYear;
mDay = dayOfMonth;
updateDisplay();
}
};
Time to run our application.
We'll get something like this:
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