计算当前日期和过去日期之间的差异

Question

专家，试图展示Android Studio中两个日期之间的区别。有以下条件。

以下条件第一号工作正常。  1.当前日期与未来日期之间的差异

条件2有问题，它显示了值，但没有显示负号，以了解它已经通过。

1. 当前日期与过去日期之间的差异。

主要活动。

package com.bar.example.myapplication;

import android.app.DialogFragment;
//import android.support.design.widget.TextInputLayout;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.text.format.DateFormat;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;


import java.text.DecimalFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.concurrent.TimeUnit;

public class MainActivity extends AppCompatActivity {

  private EditText editTextDate1, editTextDate2, num1, num2;
  private TextView txtResult, tv, textDivNumber, textAVG, txtZaMisiac;
  private Button button;
  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    editTextDate1 = (EditText) findViewById(R.id.editTextDate1);
    editTextDate2 = (EditText) findViewById(R.id.editTextDate2);
    num1 = (EditText) findViewById(R.id.num1);
    num2 = (EditText) findViewById(R.id.num2);
    button = (Button) findViewById(R.id.button);
    txtResult = (TextView) findViewById(R.id.txtResult);
    textDivNumber = (TextView) findViewById(R.id.textDivNumber);
    textAVG = (TextView) findViewById(R.id.textAVG);
    txtZaMisiac = (TextView) findViewById(R.id.txtZaMisiac);
    tv = (TextView) findViewById(R.id.tv);
    tv.setText("Current date " + (DateFormat.format("dd.MM.yyyy", new java.util.Date()).toString()));
    editTextDate1.setText(DateFormat.format("dd.MM.yyyy", new java.util.Date()).toString());

  }

  public void diff(View view) {
    SimpleDateFormat myFormat = new SimpleDateFormat("dd.MM.yyyy");
    String inputString1 = editTextDate1.getText().toString();
    String inputString2 = editTextDate2.getText().toString();
    String number11 = num1.getText().toString();
    String number12 = num2.getText().toString();

    String[] isbnParts = inputString1.split("\\.");
    if (Integer.parseInt(isbnParts[0]) > 31) {
      Toast.makeText(this, "It looks like you've typed too many days in a month", Toast.LENGTH_SHORT).show();
    }
    if (Integer.parseInt(isbnParts[1]) > 12) {
      Toast.makeText(this, "Gm ... introduced a non-existent month)", Toast.LENGTH_SHORT).show();
    }

    String[] isbnParts1 = inputString2.split("\\.");
    if (Integer.parseInt(isbnParts1[0]) > 31) {
      Toast.makeText(this, "Hey ... too many days in a month", Toast.LENGTH_SHORT).show();
    }
    if (Integer.parseInt(isbnParts1[1]) > 12) {
      Toast.makeText(this, "Hmm ... you entered a non-existent month)", Toast.LENGTH_SHORT).show();
    }

    if (inputString1.matches("") || inputString2.matches("")) {
      Toast.makeText(this, "No dates entered", Toast.LENGTH_SHORT).show();
    } else {

      try {
        Date date1 = myFormat.parse(inputString1);
        Date date2 = myFormat.parse(inputString2);
        long diffDate = Math.abs(date2.getTime() - date1.getTime());
        txtResult.setText("" + TimeUnit.DAYS.convert(diffDate, TimeUnit.MILLISECONDS));

      } catch (ParseException e) {
        e.printStackTrace();
      }
      if (number11.matches("") || number12.matches("")) {
        Toast.makeText(this, "No numbers entered for calculation", Toast.LENGTH_SHORT).show();
      } else {

        String pattern = "##0.00";
        String pattern1 = "##0";
        DecimalFormat decimalFormat = new DecimalFormat(pattern);
        DecimalFormat decimalFormat1 = new DecimalFormat(pattern1);

        float number1 = Integer.parseInt(number11);
        float number2 = Integer.parseInt(number12);
        float diffDateInt = Integer.parseInt(txtResult.getText().toString());
        float diffnumb = Math.abs(number1 - number2);
        String format3 = decimalFormat1.format(diffnumb);
        textDivNumber.setText(String.valueOf(format3));
        String format = decimalFormat.format((diffnumb / diffDateInt) * 30.00);
        txtZaMisiac.setText(String.valueOf(format));
        String format1 = decimalFormat.format(diffnumb / diffDateInt);
        textAVG.setText(String.valueOf(format1));
      }
    }
  }

  public void setDate1(View view) {
    DialogFragment newFragment = new DatePickerFragment();
    newFragment.show(getFragmentManager(), "Date Picker");
  }
  public void setDate2(View view) {
    DialogFragment newFragment = new DatePickerFragment2();
    newFragment.show(getFragmentManager(), "Date Picker");
  }
}

DatePickerFragment.java

package com.bar.example.myapplication;

import android.app.DatePickerDialog;
import android.app.DialogFragment;
import android.os.Bundle;
import android.widget.EditText;
import android.widget.DatePicker;
import android.app.Dialog;
import java.util.Calendar;

public class DatePickerFragment extends DialogFragment implements DatePickerDialog.OnDateSetListener {

  @Override
  public Dialog onCreateDialog(Bundle savedInstanceState) {

    final Calendar c = Calendar.getInstance();
    int year = c.get(Calendar.YEAR);
    int month = c.get(Calendar.MONTH);
    int day = c.get(Calendar.DAY_OF_MONTH);
    return new DatePickerDialog(getActivity(), this, year, month, day);
  }
  public void onDateSet(DatePicker view, int year, int month, int day) {
    EditText editTextDate1 = (EditText) getActivity().findViewById(R.id.editTextDate1);
    String stringOfDate = day + "." + (month + 1) + "." + year;
    editTextDate1.setText(stringOfDate);
  }
}

DatePickerFragment2.java

package com.bar.example.myapplication;

import android.app.DatePickerDialog;
import android.app.Dialog;
import android.app.DialogFragment;
import android.os.Bundle;
import android.widget.DatePicker;
import android.widget.EditText;


import java.util.Calendar;

public class DatePickerFragment2 extends DialogFragment implements DatePickerDialog.OnDateSetListener {

  @Override
  public Dialog onCreateDialog(Bundle savedInstanceState) {

    final Calendar c = Calendar.getInstance();
    int year = c.get(Calendar.YEAR);
    int month = c.get(Calendar.MONTH);
    int day = c.get(Calendar.DAY_OF_MONTH);
    return new DatePickerDialog(getActivity(), this, year, month, day);
  }

  public void onDateSet(DatePicker view, int year, int month, int day) {
    EditText editTextDate2 = (EditText) getActivity().findViewById(R.id.editTextDate2);
    String stringOfDate = day + "." + (month + 1) + "." + year;
    editTextDate2.setText(stringOfDate);
  }
}

布局

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
    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:padding="16dp"
    android:background="#B3E5FC"
    tools:context=".MainActivity"
    >
    <!--This example works only date picker mode = spinner mode only-->
    <!--DatePicker with spinner and without Calendar-->
    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="set date 1"
        android:id="@+id/btnDate1" android:layout_alignParentTop="true" android:layout_alignParentLeft="true"
        android:layout_marginTop="42dp" android:onClick="setDate1"/>
    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="set date 2"
        android:id="@+id/btnDate2" android:layout_alignTop="@+id/btnDate1" android:layout_alignParentRight="true"
        android:onClick="setDate2"/>
    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="calculate"
        android:id="@+id/button"
        android:onClick="diff" android:layout_centerVertical="true" android:layout_centerHorizontal="true"
        android:textColor="#f21124"/>
    <EditText
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/editTextDate1" android:layout_below="@+id/btnDate1" android:layout_alignParentLeft="true"
        android:layout_alignRight="@+id/btnDate1"
        android:inputType="date" android:textColor="#9e0e1f" android:textSize="15dp"/>
    <EditText
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/editTextDate2" android:layout_below="@+id/btnDate2"
        android:layout_alignRight="@+id/btnDate2" android:layout_alignLeft="@+id/btnDate2"
        android:inputType="date" android:textColor="#e11515" android:textSize="15dp"/>
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textAppearance="?android:attr/textAppearanceLarge"
        android:id="@+id/txtResult"
        android:text="............"
        android:textSize="14dp" android:layout_below="@+id/button" android:layout_alignLeft="@+id/num2"
        android:layout_alignStart="@+id/num2" android:textColor="#5c2e2e"/>
    <EditText
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:inputType="number"
        android:ems="10"
        android:id="@+id/num1" android:layout_below="@+id/editTextDate1" android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:layout_toStartOf="@+id/button" android:layout_alignRight="@+id/editTextDate1"
        android:layout_alignEnd="@+id/editTextDate1" android:textColor="#590e9b" android:textSize="15dp"/>
    <EditText
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:inputType="number"
        android:ems="10"
        android:id="@+id/num2" android:layout_below="@+id/editTextDate2" android:layout_alignParentRight="true"
        android:layout_alignParentEnd="true" android:layout_alignLeft="@+id/editTextDate2"
        android:layout_alignStart="@+id/editTextDate2" android:textColor="#3818ad" android:textSize="15dp"/>

    <TextView
        android:id="@+id/textView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignBottom="@+id/txtResult"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:text="Between dates"
        android:textAppearance="?android:attr/textAppearanceMedium"
        android:textColor="#060606"
        android:textSize="14dp" />

    <TextView
        android:id="@+id/textView2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:layout_below="@+id/textView"
        android:text="The difference between the numbers"
        android:textAppearance="?android:attr/textAppearanceMedium"
        android:textColor="#070707"
        android:textSize="14dp" />
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textAppearance="?android:attr/textAppearanceMedium"
        android:text="............"
        android:id="@+id/textDivNumber"
        android:layout_below="@+id/txtResult" android:layout_alignLeft="@+id/txtResult"
        android:layout_alignStart="@+id/txtResult" android:textColor="#782f2f" android:textSize="14dp"/>

    <TextView
        android:id="@+id/textView4"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:layout_below="@+id/textView2"
        android:text="Average value"
        android:textAppearance="?android:attr/textAppearanceMedium"
        android:textColor="#0a0a0a"
        android:textSize="14dp" />
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textAppearance="?android:attr/textAppearanceMedium"
        android:text="............"
        android:id="@+id/textAVG"
        android:layout_below="@+id/textDivNumber" android:layout_alignLeft="@+id/textDivNumber"
        android:layout_alignStart="@+id/textDivNumber" android:textColor="#7e3333" android:textSize="14dp"/>
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textAppearance="?android:attr/textAppearanceSmall"
        android:text="Small Text"
        android:id="@+id/tv"
        android:layout_alignParentTop="true" android:layout_centerHorizontal="true"/>

    <TextView
        android:id="@+id/textView3"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_above="@+id/textDivNumber"
        android:layout_alignParentEnd="true"
        android:layout_alignParentRight="true"
        android:text="days"
        android:textAppearance="?android:attr/textAppearanceSmall" />

    <TextView
        android:id="@+id/textView5"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/textView3"
        android:layout_alignParentEnd="true"
        android:layout_alignParentRight="true"
        android:layout_alignStart="@+id/textView3"
        android:layout_below="@+id/textDivNumber"
        android:text="in a day"
        android:textAppearance="?android:attr/textAppearanceSmall"
        android:textSize="10dp" />

    <TextView
        android:id="@+id/textView6"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:layout_alignTop="@+id/txtZaMisiac"
        android:text="Per month"
        android:textAppearance="?android:attr/textAppearanceMedium"
        android:textColor="#171414"
        android:textSize="14dp" />
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textAppearance="?android:attr/textAppearanceMedium"
        android:text="............"
        android:id="@+id/txtZaMisiac"
        android:layout_below="@+id/textView5" android:layout_alignLeft="@+id/textAVG"
        android:layout_alignStart="@+id/textAVG" android:textSize="14dp" android:textColor="#052df7"/>
</RelativeLayout>

条件第一，工作正常（当前日期与未来日期）。截图截图。

条件数二（当前日期与过去日期），显示值而不是负值-29。

新差异代码

＆＃13;
＆＃13;
public void diff(View view) {

  //  SimpleDateFormat myFormat = new SimpleDateFormat("dd.MM.yyyy");
  // String inputString1 = ok.getText().toString();
  //  String inputString2 = ok1.getText().toString();
  CharSequence inputString1 = editTextDate1.getText();

  try {
    LocalDate date1 = LocalDate.parse(inputString1, dateFormatter);
    CharSequence inputString2 = editTextDate2.getText();
    try {
      LocalDate date2 = LocalDate.parse(inputString2, dateFormatter);
      long diffDate = ChronoUnit.DAYS.between(date1, date2);
      txtResult.setText(String.valueOf(diffDate));
    } catch (DateTimeParseException dtpe) {
      Toast.makeText(this, "Date2 is not a valid date: " + inputString2, Toast.LENGTH_SHORT).show();
    }
  } catch (DateTimeParseException dtpe) {
    Toast.makeText(this, "Date1 is not a valid date: " + inputString1, Toast.LENGTH_SHORT).show();
  }
  //   if (number11.matches("")||number12.matches("")){Toast.makeText(this, "No numbers entered for calculation", Toast.LENGTH_SHORT).show();}

}
＆＃13;
＆＃13;
＆＃13;

Answer 1

java.time

让我们首先声明一个格式化程序。这可能是一个静态字段：

private static DateTimeFormatter dateFormatter
        = DateTimeFormatter.ofPattern("d.M.uuuu");

然后在diff中的MainActivity方法中，您可能会执行以下操作：

    CharSequence inputString1 = editTextDate1.getText();
    try {
        LocalDate date1 = LocalDate.parse(inputString1, dateFormatter);
        CharSequence inputString2 = editTextDate2.getText();
        try {
            LocalDate date2 = LocalDate.parse(inputString2, dateFormatter);
            long diffDate = ChronoUnit.DAYS.between(date1, date2);
            txtResult.setText(String.valueOf(diffDate));
        } catch (DateTimeParseException dtpe) {
            Toast.makeText(this, "Date2 is not a valid date: " + inputString2, Toast.LENGTH_SHORT).show();
        }
    } catch (DateTimeParseException dtpe) {
        Toast.makeText(this, "Date1 is not a valid date: " + inputString1, Toast.LENGTH_SHORT).show();
    }

• 如果日期为5.5.2018和31.5.2018，则会显示26的差异。
• 如果日期为5.5.2018和1.5.2018，则会显示-4的差异。

您的代码出了什么问题？

我相信这条线是罪魁祸首：

        long diffDate = Math.abs(date2.getTime() - date1.getTime());

Math.abs()获取参数的绝对值，即将负数转换为正数。所以无论日期是过去还是将来，你都会得到一个正数。从毫秒转换为天后，您仍然有一个正数，因此它显示没有符号。

也就是说，您使用的日期和时间类Calendar，Date和SimpleDateFormat已经过时且设计不佳。 SimpleDateFormat特别是出了名的麻烦。考虑避免它们并使用java.time，即现代Java日期和时间API。

问题：我可以在Android上使用java.time吗？

是的，java.time适用于较旧和较新的Android设备。它至少需要 Java 6 。

• 在Java 8及更高版本和新的Android设备上（来自API级别26，我被告知）新的API内置。
• 在Java 6和7中获取ThreeTen Backport，这是新类的后端（JST 310的ThreeTen，其中首次描述了现代API）。
• 在（较旧的）Android上，使用Android版的ThreeTen Backport。它被称为ThreeTenABP。确保从包org.threeten.bp和子包中导入日期和时间类。

链接

• Oracle tutorial: Date Time，解释了如何使用java.time。
• ThreeTen Backport project
• ThreeTenABP，Android版ThreeTen Backport
• Question: How to use ThreeTenABP in Android Project，有一个非常详尽的解释。
• Java Specification Request (JSR) 310。