p7

 activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <Button
        android:id="@+id/btn_call"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="CALL"
        android:textSize="24sp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.154"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.944" />


    <Button
        android:id="@+id/btn_save"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="SAVE"
        android:textSize="24sp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.716"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.944" />

    <Button
        android:id="@+id/btn_four"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="4"
        android:textSize="24sp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.123"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.521" />

    <Button
        android:id="@+id/btn_eight"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="8"
        android:textSize="24sp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.461"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.662" />

    <Button
        android:id="@+id/btn_seven"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="7"
        android:textSize="24sp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.105"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.662" />

    <Button
        android:id="@+id/btn_zero"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="0"
        android:textSize="24sp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.461"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.804" />

    <Button
        android:id="@+id/btn_star"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="*"
        android:textSize="24sp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.145"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.804" />

    <Button
        android:id="@+id/btn_hash"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="#"
        android:textSize="24sp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.814"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.804" />

    <Button
        android:id="@+id/btn_nine"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="9"
        android:textSize="24sp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.814"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.662" />


    <Button
        android:id="@+id/btn_five"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="5"
        android:textSize="24sp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.439"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.521" />

    <Button
        android:id="@+id/btn_six"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="6"
        android:textSize="24sp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.792"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.521" />

    <Button
        android:id="@+id/btn_three"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="3"
        android:textSize="24sp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.792"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.39" />

    <Button
        android:id="@+id/btn_one"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="1"
        android:textSize="24sp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.125"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.39" />

    <Button
        android:id="@+id/btn_two"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="2"
        android:textSize="24sp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.461"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.39" />
    <TextView
        android:id="@+id/textView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="CALL AND SAVE APPLICATION"
        android:textAlignment="center"
        android:textColor="#5E35B1"
        android:textSize="24sp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.097" />

    <Button
        android:id="@+id/btn_delete"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="DEL"
        android:textSize="24sp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.915"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.259" />

    <EditText
        android:id="@+id/txt_phonenumber"
        android:layout_width="269dp"
        android:layout_height="67dp"
        android:ems="10"
        android:inputType="phone"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.112"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.265" />

</androidx.constraintlayout.widget.ConstraintLayout>

mainactivity.java

package com.example.dailer;

import androidx.appcompat.app.AppCompatActivity;

import android.content.Intent;
import android.net.Uri;
import android.os.Bundle;
import android.provider.ContactsContract;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;

public class MainActivity extends AppCompatActivity implements
        View.OnClickListener {

    Button btnOne, btnTwo, btnThree, btnFour, btnFive, btnSix,
            btnSeven, btnEight, btnNine, btnZero;
    Button btnSave, btnDel, btnStar, btnHash, btnCall;
    EditText txtPhone;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        btnOne = (Button) findViewById(R.id.btn_one);
        btnOne.setOnClickListener(this);

        btnTwo = (Button) findViewById(R.id.btn_two);
        btnTwo.setOnClickListener(this);

        btnThree = (Button) findViewById(R.id.btn_three);
        btnThree.setOnClickListener(this);

        btnFour = (Button) findViewById(R.id.btn_four);
        btnFour.setOnClickListener(this);

        btnFive = (Button) findViewById(R.id.btn_five);
        btnFive.setOnClickListener(this);

        btnSix = (Button) findViewById(R.id.btn_six);
        btnSix.setOnClickListener(this);

        btnSeven = (Button) findViewById(R.id.btn_seven);
        btnSeven.setOnClickListener(this);
        btnEight = (Button) findViewById(R.id.btn_eight);
        btnEight.setOnClickListener(this);

        btnNine = (Button) findViewById(R.id.btn_nine);
        btnNine.setOnClickListener(this);

        btnZero = (Button) findViewById(R.id.btn_zero);
        btnZero.setOnClickListener(this);

        btnSave = (Button) findViewById(R.id.btn_save);
        btnSave.setOnClickListener(this);

        btnCall = (Button) findViewById(R.id.btn_call);
        btnCall.setOnClickListener(this);

        btnHash = (Button) findViewById(R.id.btn_hash);
        btnHash.setOnClickListener(this);

        btnStar = (Button) findViewById(R.id.btn_star);
        btnStar.setOnClickListener(this);

        btnDel = (Button) findViewById(R.id.btn_delete);
        btnDel.setOnClickListener(this);

        txtPhone = (EditText)
                findViewById(R.id.txt_phonenumber);
        txtPhone.setText("");
    }

    @Override
    public void onClick(View v) {
        if (v.equals(btnOne))
            txtPhone.append("1");
        else if (v.equals(btnTwo))
            txtPhone.append("2");
        else if (v.equals(btnThree))
            txtPhone.append("3");
        else if (v.equals(btnFour))
            txtPhone.append("4");
        else if (v.equals(btnFive))
            txtPhone.append("5");
        else if (v.equals(btnSix))
            txtPhone.append("6");
        else if (v.equals(btnSeven))
            txtPhone.append("7");
        else if (v.equals(btnEight))
            txtPhone.append("8");
        else if (v.equals(btnNine))
            txtPhone.append("9");
        else if (v.equals(btnZero))
            txtPhone.append("0");
        else if (v.equals(btnHash))
            txtPhone.append("#");
        else if (v.equals(btnStar))
            txtPhone.append("*");

        else if (v.equals(btnSave)) {
            Intent contactIntent = new
                    Intent(ContactsContract.Intents.Insert.ACTION);

            contactIntent.setType(ContactsContract.RawContacts.CONTENT_TYPE)
            ;

            contactIntent.putExtra(ContactsContract.Intents.Insert.NAME,
                    "Parveen");

            contactIntent.putExtra(ContactsContract.Intents.Insert.PHONE,
                    txtPhone.getText().toString());
            startActivity(contactIntent);
        } else if (v.equals(btnDel)) {
            String data = txtPhone.getText().toString();

            if (data.length() > 0)
                txtPhone.setText(data.substring(0, data.length() - 1));
            else
                txtPhone.setText("");
        }
        btnCall.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String data = txtPhone.getText().toString();
                Intent i = new Intent(Intent.ACTION_DIAL);
                i.setData(Uri.parse("tel:" + data));
                startActivity(i);
            }
        });
    }
}