How to recyclerView Item on the basis of boolean parameter and only display true items?

Question

I have a question that how can I sort Arraylist in on the basis of boolean parameter and only display true items. datasource.sortByDescending { it.favorite } Here I am getting sorted array in which I got true items on top and false items on bottom. What I want is that it only display true items and not display false items.

I hope I am clear with my question.

Full Code is below:

class MainActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_main)

    rvlist.layoutManager = LinearLayoutManager(this,LinearLayoutManager.VERTICAL,false)
    val datasource = getDataSource()
    val beneficiaryAdapter = BeneficiaryAdapter(datasource)
    rvlist.adapter = beneficiaryAdapter

    btnAll.setOnClickListener{
        btnFavorite.setBackgroundColor(Color.BLUE)
        btnAll.setBackgroundColor(Color.GREEN)
        btnSortByFrequency.setBackgroundColor(Color.BLUE)
        btnSortByName.setBackgroundColor(Color.BLUE)

        rvlist.layoutManager = LinearLayoutManager(this,LinearLayoutManager.VERTICAL,false)
        val datasource = getDataSource()
        val beneficiaryAdapter = BeneficiaryAdapter(datasource)
        rvlist.adapter = beneficiaryAdapter
    }

    btnFavorite.setOnClickListener{
        btnFavorite.setBackgroundColor(Color.GREEN)
        btnAll.setBackgroundColor(Color.BLUE)
        btnSortByFrequency.setBackgroundColor(Color.BLUE)
        btnSortByName.setBackgroundColor(Color.BLUE)

        rvlist.layoutManager = LinearLayoutManager(this,LinearLayoutManager.VERTICAL,false)
        val datasource = getDataSource()
        datasource.sortByDescending { it.favorite }
        val beneficiaryAdapter = BeneficiaryAdapter(datasource)
        rvlist.adapter = beneficiaryAdapter
    }

    btnSortByFrequency.setOnClickListener{
        btnFavorite.setBackgroundColor(Color.BLUE)
        btnAll.setBackgroundColor(Color.BLUE)
        btnSortByFrequency.setBackgroundColor(Color.GREEN)
        btnSortByName.setBackgroundColor(Color.BLUE)

        rvlist.layoutManager = LinearLayoutManager(this,LinearLayoutManager.VERTICAL,false)
        val datasource = getDataSource()
        datasource.sortByDescending { it.frequency }
        val beneficiaryAdapter = BeneficiaryAdapter(datasource)
        rvlist.adapter = beneficiaryAdapter
    }

    btnSortByName.setOnClickListener{
        btnFavorite.setBackgroundColor(Color.BLUE)
        btnAll.setBackgroundColor(Color.BLUE)
        btnSortByFrequency.setBackgroundColor(Color.BLUE)
        btnSortByName.setBackgroundColor(Color.GREEN)

        rvlist.layoutManager = LinearLayoutManager(this,LinearLayoutManager.VERTICAL,false)
        val datasource = getDataSource()
        datasource.sortBy { it.name }
        val beneficiaryAdapter = BeneficiaryAdapter(datasource)
        rvlist.adapter = beneficiaryAdapter
    }

}

private fun getDataSource():ArrayList<beneficiary>{
    val list = ArrayList<beneficiary>()
    list.add(beneficiary(1, "Adbul Malik", "12346564555124", "Meezan",true,5))
    list.add(beneficiary(2, "Naeem Ali", "6454886614281", "HBL",true,5))
    list.add(beneficiary(3, "Ali Raza", "456467864568465", "Soneri",false,4))
    list.add(beneficiary(4, "Talha Abid", "46873456465464564", "Allied",false,1))
    list.add(beneficiary(5, "Hassan Ali", "16456464564646", "Meezan",false,5))
    list.add(beneficiary(6, "Shahid Khan", "78946756195845648", "HBL",true,3))
    list.add(beneficiary(7, "Umer Riaz", "79464567754379", "Soneri",false,6))
    list.add(beneficiary(8, "Zeeshan Farooq", "797536187897465", "Allied",false,1))
    list.add(beneficiary(9, "Qasim Ali", "551988763478565746765", "MCB",false,1))
    list.add(beneficiary(10, "Farooq Haider", "81786523478465010", "Punjab",false,2))

    return list
}

}

Does this answer your question? [How to filter a Java Collection (based on predicate)?](https://stackoverflow.com/questions/122105/how-to-filter-a-java-collection-based-on-predicate) — Mehdi Dehghani, Apr 15 '22 at 16:24

Berk Berber · Accepted Answer · 2022-04-15T16:46:29.690

You can basically filter your array list as below

getDataSource().filter { it.favorite }

You can update your code as below:

btnFavorite.setOnClickListener{
        btnFavorite.setBackgroundColor(Color.GREEN)
        btnAll.setBackgroundColor(Color.BLUE)
        btnSortByFrequency.setBackgroundColor(Color.BLUE)
        btnSortByName.setBackgroundColor(Color.BLUE)

        rvlist.layoutManager = LinearLayoutManager(this,LinearLayoutManager.VERTICAL,false)
        val beneficiaryAdapter = BeneficiaryAdapter(getDataSource().filter { it.favorite })
        rvlist.adapter = beneficiaryAdapter
    }

This won't update your dataSource variable after you tried to change. You have to put it into new variable or directly use it on where you are going to use

val datasource = getDataSource()
datasource.sortByDescending { it.frequency }

I have tested and it works. You probably do it on variable directly, but it doesn't update your old variable as you have did. I have updated my code, if still has issues, let me know — Berk Berber, Apr 15 '22 at 16:47

How to recyclerView Item on the basis of boolean parameter and only display true items?

1 Answers1