我有两个日期的字符串格式，并使用共享首选项存储它。第一个日期（当前日期）设置为日期选择日期，第二个日期是第一个日期添加41天后的日期。我有一个按钮以天为单位来获取两个日期之间的差异。它是使用共享首选项存储的。问题是我必须根据每个当前日期减少这两个日期之间的差异。如何做到这一点？请帮助... < / p>
import android.app.Activity;
import android.app.DatePickerDialog;
import android.app.Dialog;
import android.content.Intent;
import java.util.Calendar;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.DatePicker;
import android.widget.ImageButton;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeUnit;
import static com.example.aiswarya.mantraapp.R.id.end;
//import static com.example.aiswarya.mantraapp.R.id.enddate;
import static com.example.aiswarya.mantraapp.R.id.imageView;
import static com.example.aiswarya.mantraapp.R.id.myImageViewText;
//import static com.example.aiswarya.mantraapp.R.id.startdate;
import static com.example.aiswarya.mantraapp.R.id.textView3;
/**
* Created by aiswarya on 3/24/2017.
*/
public class Fasting extends AppCompatActivity {
ImageButton backb;
ImageButton reset;
TextView startdate,enddate;
ImageView remaining;
TextView remainingtext;
SharedPreferences myprefs;
public String dayys;
public long from,to;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activitydate);
backb=(ImageButton) findViewById(R.id.back);
reset= (ImageButton) findViewById(R.id.reset);
// startdate= (TextView) findViewById(R.id.textView2);
// enddate= (TextView) findViewById(textView3);
remaining=(ImageView) findViewById(R.id.myImageView);
//remainingtext=(TextView) findViewById(R.id.myImageViewText);
backb.setOnClickListener(new View.OnClickListener(){
@Override
public void onClick(View v) {
Intent intent = new Intent(Fasting.this,
Home.class);
startActivity(intent);
}
});
reset.setOnClickListener(new View.OnClickListener(){
@Override
public void onClick(View v) {
startdate.setText("START DATE");
enddate.setText("END DATE");
remainingtext.setText("REMAINING DAYS");
}
});
myprefs=getPreferences(MODE_PRIVATE);
init();
}
public void selectFrom(View v) {
final Calendar today = Calendar.getInstance();
DatePickerDialog dp = new DatePickerDialog(Fasting.this, new DatePickerDialog.OnDateSetListener() {
@Override
public void onDateSet(DatePicker view, int year, int month, int dayOfMonth) {
Log.d("date", dayOfMonth + "/" + month + "/" + year);
Calendar cal = Calendar.getInstance();
cal.set(Calendar.DAY_OF_MONTH, dayOfMonth);
cal.set(Calendar.MONTH, month);
cal.set(Calendar.YEAR, year);
((TextView)findViewById(R.id.textView2)).setText(cal.get(Calendar.DAY_OF_MONTH) + "-" + (cal.get(Calendar.MONTH)+1) + "-" + cal.get(Calendar.YEAR));
cal.add(Calendar.DAY_OF_MONTH, 41);
((TextView)findViewById(textView3)).setText(cal.get(Calendar.DAY_OF_MONTH) + "-" + (cal.get(Calendar.MONTH)+1) + "-" + cal.get(Calendar.YEAR));
long from = today.getTimeInMillis();
long to = cal.getTimeInMillis();
int days = (int) TimeUnit.MILLISECONDS.toDays(Math.abs(from - to));
Toast.makeText(getApplicationContext(), "DAYS = " + days, Toast.LENGTH_LONG).show();
final String dayss=String.valueOf(days);
remaining.setOnClickListener(new View.OnClickListener(){
@Override
public void onClick(View v){
remainingtext.setText(""+dayss+" DAYS");
}
});
}
}, today.get(Calendar.YEAR), today.get(Calendar.MONTH), today.get(Calendar.DAY_OF_MONTH));
dp.show();
}
private void init(){
startdate=(TextView) findViewById(R.id.textView2);
enddate=(TextView) findViewById(R.id.textView3);
remainingtext=(TextView) findViewById(R.id.myImageViewText);
readPreferences();
}
public void onSave(View view) {
String start=startdate.getText().toString();
String end=enddate.getText().toString();
String rem=remainingtext.getText().toString();
//int ageText=Integer.parseInt(age.getText().toString());
SharedPreferences.Editor editor=myprefs.edit();
editor.putString("keyname",start);
editor.putString("keyage",end);
editor.putString("keyrem",rem);
editor.commit();
}
public void onReset(View view) {
SharedPreferences.Editor editor=myprefs.edit();
editor.clear();
editor.commit();
readPreferences();
}
public void readPreferences(){
String stl= myprefs.getString("keyname","");
startdate.setText(stl);
//int vall=myprefs.getInt("keyage",0);
String vall=myprefs.getString("keyage","");
enddate.setText(String.valueOf(vall));
String remdays=myprefs.getString("keyrem","");
remainingtext.setText(String.valueOf(remdays));
}
}
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
tools:context="com.example.aiswarya.mantraapp.Fasting">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="40dp"
android:background="@drawable/linir_back"
>
<ImageButton
android:id="@+id/back"
android:layout_width="50dp"
android:layout_marginTop="5dp"
android:layout_height="30dp"
android:background="@drawable/linir_back"
android:src="@drawable/back_button"/>
<TextView
android:gravity="center"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="FASTING"
android:textSize="30dp"
android:textColor="@color/colorBlue"
android:textStyle="bold"
/>
</LinearLayout>
<TextView
android:id="@+id/textView2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textColorHint="@color/colorAccent"
android:textStyle="bold"
android:textColor="@color/colorAccent"
android:visibility="visible"
android:onClick="selectFrom"
android:layout_marginTop="5dp"
android:text="START DATE"
android:textAppearance="?android:attr/textAppearanceMedium" />
<TextView
android:id="@+id/textView3"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@+id/textView2"
android:layout_marginTop="10dp"
android:textColorHint="@color/colorAccent"
android:textStyle="bold"
android:textColor="@color/colorAccent"
android:visibility="visible"
android:text="END DATE"
android:textAppearance="?android:attr/textAppearanceMedium" />
<ImageButton
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:src="@drawable/submit4resized1"
android:onClick="onSave"
android:layout_marginLeft="90dp"
/>
<ImageButton
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/reset"
android:src="@drawable/resetbutton"
android:layout_marginTop="5dp"
android:background="@color/colorWhite"
android:layout_marginLeft="70dp"
android:onClick="onReset" />
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="216dp">
<ImageView
android:id="@+id/myImageView"
android:layout_width="200dp"
android:layout_height="150dp"
android:onClick="showDiff"
android:src="@drawable/new1"
android:layout_marginRight="63dp"
android:layout_marginEnd="63dp"
android:layout_alignParentTop="true"
android:layout_alignParentRight="true"
android:layout_alignParentEnd="true" />
<TextView
android:id="@+id/myImageViewText"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:gravity="center"
android:text="REMAINING DAYS"
android:textColor="@color/colorWhite"
android:layout_marginRight="41dp"
android:layout_marginEnd="41dp"
android:layout_alignBottom="@+id/myImageView"
android:layout_alignRight="@+id/myImageView"
android:layout_alignEnd="@+id/myImageView"
android:layout_marginBottom="65dp" />
</RelativeLayout>