how to calculate age or difference between two dates in java

Question

I want to get the number of months between 2 dates.The dates are someones birthday and the current date.So i m getting the number of years in between the two dates but not the number of months..

Suppose my dates are 06/09/2011 and 06/11/2012.So i want the answer to be 1yr 2mths .I am getting the year but not the month.Please help.Below is the code for getting the number of years

 public int getAge(Date dateOfBirth)      {                                                                                                                                                                         

    today = Calendar.getInstance(); 
    Calendar birthDate = Calendar.getInstance();

    birthDate.setTime(dateOfBirth);
    if (birthDate.after(today)) {
        throw new IllegalArgumentException("Can't be born in the future");
    }

    age = today.get(Calendar.YEAR) - birthDate.get(Calendar.YEAR);
    month = today.get(Calendar.MONTH) - birthDate.get(Calendar.MONTH);

    if ( (birthDate.get(Calendar.DAY_OF_YEAR) - today.get(Calendar.DAY_OF_YEAR) > 3) ||
            (birthDate.get(Calendar.MONTH) > today.get(Calendar.MONTH ))){
        days = birthDate.get(Calendar.DAY_OF_MONTH) - today.get(Calendar.DAY_OF_MONTH);
        age--;

        Toast.makeText(getApplicationContext(), "inside if", Toast.LENGTH_SHORT).show();
        Log.e("month is",month+"");
        Log.e("Days",days+ " left");


    }else if ((birthDate.get(Calendar.MONTH) == today.get(Calendar.MONTH )) &&
              (birthDate.get(Calendar.DAY_OF_MONTH) > today.get(Calendar.DAY_OF_MONTH ))){
        Toast.makeText(getApplicationContext(), "inside else if", Toast.LENGTH_SHORT).show();

        age--;
    }

    return age;

Answer 1

I have recently created a demo and uploaded here.

It is using JodaTime library for efficient results.

I hope it will be useful.

Screenshot:

Code:

MainActivity.java

public class MainActivity extends Activity {

    private SimpleDateFormat mSimpleDateFormat;
    private PeriodFormatter mPeriodFormat;

    private Date startDate;
    private Date endDate;
    private Date birthDate;


    private TextView tvStartDate,tvEndDate,tvDifferenceStandard,tvDifferenceCustom,tvBirthDate,tvAgeStandard,tvAgeCustom;

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

        init();

        //determine dateDiff
        Period dateDiff = calcDiff(startDate,endDate);
        tvDifferenceStandard.setText(PeriodFormat.wordBased().print(dateDiff));
        tvDifferenceCustom.setText( mPeriodFormat.print(dateDiff));


        //determine age
        Period age = calcDiff(birthDate,new Date());
        tvAgeStandard.setText(PeriodFormat.wordBased().print(age));
        tvAgeCustom.setText( mPeriodFormat.print(age));

    }

    private void init() {

        //ui
        tvStartDate = (TextView)findViewById(R.id.tvStartDate);
        tvEndDate = (TextView)findViewById(R.id.tvEndDate);
        tvDifferenceStandard = (TextView)findViewById(R.id.tvDifferenceStandard);
        tvDifferenceCustom = (TextView)findViewById(R.id.tvDifferenceCustom);
        tvBirthDate = (TextView)findViewById(R.id.tvBirthDate);
        tvAgeStandard = (TextView)findViewById(R.id.tvAgeStandard);
        tvAgeCustom = (TextView)findViewById(R.id.tvAgeCustom);



        //components
        mSimpleDateFormat = new SimpleDateFormat("dd/MM/yy");
        mPeriodFormat = new PeriodFormatterBuilder().appendYears().appendSuffix(" year(s) ").appendMonths().appendSuffix(" month(s) ").appendDays().appendSuffix(" day(s) ").printZeroNever().toFormatter();


        try {
            startDate = mSimpleDateFormat.parse(tvStartDate.getText().toString());
            endDate =  mSimpleDateFormat.parse(tvEndDate.getText().toString());
            birthDate = mSimpleDateFormat.parse(tvBirthDate.getText().toString());

        } catch (ParseException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }

    private Period calcDiff(Date startDate,Date endDate)
    {
        DateTime START_DT = (startDate==null)?null:new DateTime(startDate);
        DateTime END_DT = (endDate==null)?null:new DateTime(endDate);

        Period period = new Period(START_DT, END_DT);

        return period;

    }

}

activity_main.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".MainActivity" >


<TextView 
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:text="Date Diff Calculator"
    android:textStyle="bold"
    android:gravity="center"
    android:background="@android:color/darker_gray"
    />


<TextView
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:textStyle="bold"
    android:text="Start Date:" />

<TextView
    android:id="@+id/tvStartDate"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:text="06/09/2011" />

<TextView
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:textStyle="bold"
    android:text="End Date:" />

<TextView
    android:id="@+id/tvEndDate"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:text="29/10/2013" />

<TextView
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:textStyle="bold"
    android:text="Difference (Standard)" />

<TextView
    android:id="@+id/tvDifferenceStandard"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:text="result" />

<TextView
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:textStyle="bold"
    android:text="Difference (Custom)" />

<TextView
    android:id="@+id/tvDifferenceCustom"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:text="result" />


<TextView 
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:text="Age Calculator"
    android:textStyle="bold"
    android:gravity="center"
    android:background="@android:color/darker_gray"
    />

<TextView
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:textStyle="bold"
    android:text="Birth Date:" />

<TextView
    android:id="@+id/tvBirthDate"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:text="01/09/1989" />

<TextView
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:textStyle="bold"
    android:text="Age (Standard)" />

<TextView
    android:id="@+id/tvAgeStandard"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:text="result" />

<TextView
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:textStyle="bold"
    android:text="Age (Custom)" />

<TextView
    android:id="@+id/tvAgeCustom"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:text="result" />

Note:

1) don't forget to add JodaTime library to your project

2) As you can see in layout file, I have used fixed value for "Start Date","End Date" to calculate Date Difference and fixed value for "Birth Date" to calculate Age. You may replace it with your dynamic values.

Answer 2

java.time

Because this answer got referenced from here…

With java.time classes you can calculate the age very easy:

long years = ChronoUnit.YEARS.between(LocalDate.of(1900, Month.NOVEMBER, 20), LocalDate.now());

or (if you need year and months)

Period p = Period.between(birthday, today);
p.getYears();
p.getMonths();

To count all the months in the entire period, as asked in the Question, call toTotalMonths.

int totalMonths = p.toTotalMonths();

Answer 3

Joda Time has code to do all this and more

You can do the following to get the month between two dates:

Calendar startCalendar = new GregorianCalendar();
startCalendar.setTime(startDate);
Calendar endCalendar = new GregorianCalendar();
endCalendar.setTime(endDate);

int diffYear = endCalendar.get(Calendar.YEAR) - startCalendar.get(Calendar.YEAR);
int diffMonth = diffYear * 12 + endCalendar.get(Calendar.MONTH) - startCalendar.get(Calendar.MONTH);

Check out Link

Note: that if your dates are 2013-01-31 and 2013-02-01, you get a distance of 1 month this way, which may or may not be what you want.

Answer 4

Age can be calculate in a very easy way. The following is my complete java code .

 public class age {


    public static void main(String [] args){
        Scanner s=new Scanner(System.in);
        Date dd=new Date();
        int d=Integer.parseInt(new SimpleDateFormat("dd").format(dd));
        int m=Integer.parseInt(new SimpleDateFormat("MM").format(dd));
        int y=Integer.parseInt(new SimpleDateFormat("yyyy").format(dd));
         System.out.println( "Enter Day ");
        int d1=Integer.parseInt(s.nextLine());
        System.out.println( "Enter Month ");
        int m1=Integer.parseInt(s.nextLine());
         System.out.println( "Year");
        int y1=Integer.parseInt(s.nextLine());
        if(d<d1){
            d+=30;
            m-=1;
        }
        if(m<m1){
            m+=12;
            y-=1;
        }
      System.out.println((y-y1)+" years "+(m-m1)+"  month "+(d-d1)+" days ");

    }
 }