Input and Output String by using EditText and Button

Activiti_main.xml Code:

<?xml version="1.0" encoding="utf-8"?>

<android.support.constraint.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="com.example.seam.addtonumber.MainActivity">

    <Button        android:id="@+id/button" 

       android:layout_width="wrap_content" 

      android:layout_height="wrap_content" 

     android:text="Button" 

       android:layout_marginTop="161dp"  

      app:layout_constraintTop_toBottomOf="@+id/editText"  

    android:layout_marginRight="8dp"  

    app:layout_constraintRight_toRightOf="parent"

     android:layout_marginLeft="8dp" 

    app:layout_constraintLeft_toLeftOf="parent" 

   app:layout_constraintBottom_toBottomOf="parent"  

      android:layout_marginBottom="8dp" />

    <EditText        android:id="@+id/editText"  

    android:layout_width="wrap_content"  

    android:layout_height="wrap_content"  

     android:ems="10"   

     android:inputType="textPersonName"    

    android:text="Name"    

    app:layout_constraintLeft_toLeftOf="parent"  

      app:layout_constraintRight_toRightOf="parent"   

     app:layout_constraintTop_toTopOf="parent"  

   android:layout_marginTop="82dp"   

     app:layout_constraintHorizontal_bias="0.502" />

</android.support.constraint.ConstraintLayout>

Main Activity.java Code:

package com.example.seam.addtonumber;

import android.provider.Settings;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {


    private EditText edittext1,edittext2;
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        setOnbutton();
    }
    public void setOnbutton()
    {
        Button bt=(Button) findViewById(R.id.button);
        //EditText e=(EditText)findViewById(R.id.editText);        edittext1=(EditText)findViewById(R.id.editText);

        bt.setOnClickListener(new View.OnClickListener()
        {
            public void onClick(View v)
            {
                String value1=edittext1.getText().toString();
                Toast.makeText(MainActivity.this, value1, Toast.LENGTH_SHORT).show();
                Toast.makeText(MainActivity.this, "Islam", Toast.LENGTH_SHORT).show();

            }
        });
    }
}