how to add a fragment in your activity by selecting items from the dropdown menu?

Question

i want to add a fragment only on selecting items from the dropdown menu and by default there should be no fragment in the activity except the dropdown. I tried using .add() function but its giving me error.

I have 2 fragments named SAR.java and Pagdi.java and the dropdown has 3 entries:select-following,sar,pagdi.

ReportIncident.xml

<?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"

    tools:context="com.example.user.sindhuworld.ReportIncident">
    <include
        android:layout_height="wrap_content"
        android:layout_width="match_parent"
        layout="@layout/toolbar_layout"
        android:id="@+id/toolBar">
    </include>
    <Spinner
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="20dp"
        android:id="@+id/spinner"
        android:entries="@array/Select_following"
        android:gravity="center"
        android:layout_below="@id/toolBar"
        android:background="@drawable/dropdownimg"
        ></Spinner>

    <FrameLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"

        android:id="@+id/sar">
    </FrameLayout>
    <FrameLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/pagdi">
    </FrameLayout>

</RelativeLayout>

ReportIncident.java here drop down has 3 entries: select_following,sar,pagdi..i don't need any fragment when the select-following item has been selected but for rest two items i want fragment to be added in the activity. Suggest the code to be written in cases or any alternative approach?

package com.example.user.sindhuworld;

import android.app.FragmentManager;
import android.app.FragmentTransaction;
import android.content.Intent;
import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.Toolbar;
import android.view.View;
import android.widget.AdapterView;
import android.widget.Spinner;

public class ReportIncident extends AppCompatActivity {
Spinner sp;
    Toolbar toolbar;
    ViewPager viewPager;
    ViewPagerAdapter viewPagerAdapter;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_report_incident);
        toolbar=(Toolbar)findViewById(R.id.toolBar);
        setSupportActionBar(toolbar);
        viewPager=(ViewPager)findViewById(R.id.viewpager);

        sp=(Spinner)findViewById(R.id.spinner);
        sp.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
            @Override
            public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
                switch (position){
                    case 0:
                    case 1:
                    case 2:

                }
            }

            @Override
            public void onNothingSelected(AdapterView<?> parent) {

            }
        });
    }
}

Answer 1

There is no need for 2 containers as you did below

<FrameLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent"

    android:id="@+id/sar">
</FrameLayout>
<FrameLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:id="@+id/pagdi">
</FrameLayout>

it's enought to use only one container then add fragmetns and remove if needed

<FrameLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:id="@+id/fragContainer">
</FrameLayout>

then inside your spinner's item selected, you should just handle case 2 and 3 because you don't anything to happen when select_following is clicked

switch (position){
    case 1:
        getSupportFragmentManager().beginTransaction().replace(R.id.fragContainer, new Sar()).commit();
        break;
    case 2:
        getSupportFragmentManager().beginTransaction().replace(R.id.fragContainer, new Pagdi()).commit();
        break;
}