how to subtract fixed number of days from a provided date by the user in android studio?

e.g. if the user fills in the date and there is a spinner consisting of three options i.e. 70,90 & 45. So if the user fills in the date and selects for example 70 & clicks submit then 20 days should be subtracted from the date filled by the user and the result should be shown i.e. the result will the date 20 days before the date filled in by the user. If selects 90 then 30 days before and so on... (java code) the ui image

<Button      android:id="@+id/backBtn7"      android:layout_width="wrap_content"      android:layout_height="wrap_content"      android:text="Back"      app:layout_constraintBottom_toBottomOf="parent"      app:layout_constraintEnd_toEndOf="parent"      app:layout_constraintHorizontal_bias="0.498"      app:layout_constraintStart_toStartOf="parent"      app:layout_constraintTop_toTopOf="parent"      app:layout_constraintVertical_bias="0.915" />    <EditText      android:id="@+id/input1"      android:layout_width="222dp"      android:layout_height="49dp"      android:ems="10"      android:hint="Shipment Date"      android:inputType="date"      app:layout_constraintBottom_toBottomOf="parent"      app:layout_constraintEnd_toEndOf="parent"      app:layout_constraintHorizontal_bias="0.532"      app:layout_constraintStart_toStartOf="parent"      app:layout_constraintTop_toTopOf="parent"      app:layout_constraintVertical_bias="0.096" />    <Spinner      android:id="@+id/spinner1"      android:layout_width="220dp"      android:layout_height="47dp"      android:text="Lead Time"      app:layout_constraintBottom_toBottomOf="parent"      app:layout_constraintEnd_toEndOf="parent"      app:layout_constraintHorizontal_bias="0.529"      app:layout_constraintStart_toStartOf="parent"      app:layout_constraintTop_toBottomOf="@+id/input1"      app:layout_constraintVertical_bias="0.063"      tools:ignore="HardcodedText" />    <Button      android:id="@+id/submitBtn2"      android:layout_width="223dp"      android:layout_height="53dp"      android:text="Submit"      app:layout_constraintBottom_toBottomOf="parent"      app:layout_constraintEnd_toEndOf="parent"      app:layout_constraintHorizontal_bias="0.539"      app:layout_constraintStart_toStartOf="parent"      app:layout_constraintTop_toBottomOf="@+id/spinner1"      app:layout_constraintVertical_bias="0.074" />    <RelativeLayout      android:layout_width="match_parent"      android:layout_height="match_parent">        <TextView          android:layout_width="wrap_content"          android:layout_height="wrap_content"          android:textAppearance="?android:attr/textAppearanceLarge"          android:id="@+id/tv_result"          android:layout_centerInParent="true" />  </RelativeLayout>  

Java Code

@Override  protected void onCreate(Bundle savedInstanceState) {      super.onCreate(savedInstanceState);      setContentView(R.layout.activity_p_c_d_calculator);      backBtn7 = findViewById(R.id.backBtn7);      submitBtn2 = findViewById(R.id.submitBtn2);      getSupportActionBar().setTitle("PCD Calculator");      tv_result = (TextView) findViewById(R.id.tv_result);      input1 = findViewById(R.id.input1);      spinner1 = findViewById(R.id.spinner1);      submitBtn2 = findViewById(R.id.submitBtn2);          submitBtn2.setOnClickListener(new View.OnClickListener() {          @Override          public void onClick(View v) {            }      });            tv_result.setText("PCD: ");          String[] users = { "70", "90", "45" };      Spinner spin = (Spinner) findViewById(R.id.spinner1);      ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, android.R.layout.simple_spinner_item, users);      adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);      spin.setPrompt("Lead Time");      spin.setAdapter(adapter);          backBtn7.setOnClickListener(new View.OnClickListener() {          @Override          public void onClick(View v) {              startActivity(new Intent(getApplicationContext(),MainActivity.class));              finish();          }      });          }  

}

https://stackoverflow.com/questions/66951164/how-to-subtract-fixed-number-of-days-from-a-provided-date-by-the-user-in-android April 05, 2021 at 05:54PM