Android

package com.kerhoas.copyString;

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.TextView;

public class MainActivity extends AppCompatActivity {

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


        final TextView textView  = (TextView) findViewById(R.id.textViewDest);
        final EditText editText  = (EditText) findViewById(R.id.editTextSource);
        Button   button    = (Button)   findViewById(R.id.button);

        button.setOnClickListener(new View.OnClickListener(){

                                      @Override
                                      public void onClick(View view) {

                                          String text = editText.getText().toString();
                                          textView.setText(text);
                                      }
                                  }
        );
    }
}

<?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.kerhoas.copyString.MainActivity">


    <EditText
        android:id="@+id/editTextSource"
        android:layout_width="250dp"
        android:layout_height="80dp"
        android:background="@android:color/holo_green_light"
        android:ems="10"
        android:gravity="center"
        android:hint="Source"
        android:inputType="textPersonName"
        app:layout_constraintBottom_toTopOf="@+id/button"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.448" />

    <Button
        android:id="@+id/button"
        android:layout_width="118dp"
        android:layout_height="77dp"
        android:layout_marginBottom="252dp"
        android:text="copy"
        android:textSize="14sp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"

        app:layout_constraintTop_toBottomOf="@+id/editTextSource"
        app:layout_constraintVertical_bias="1.0" />

    <TextView
        android:id="@+id/textViewDest"
        android:layout_width="250dp"
        android:layout_height="80dp"
        android:background="@android:color/holo_blue_bright"
        android:gravity="center"
        android:text="Destination"
        android:textAlignment="center"
        android:textAllCaps="false"
        android:textSize="18sp"
        android:textStyle="italic"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.654"

        />


</android.support.constraint.ConstraintLayout>

package kerhoas.enib.fr.chrono;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.Chronometer;
import android.os.SystemClock;

public class MainActivity extends AppCompatActivity {
    private Button startButton;
    private Button restartButton;
    private Chronometer chronometer;
    private boolean isRunning;
    private long stopTime;
    private long pauseDuration;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        startButton = (Button) findViewById(R.id.button);
        restartButton = (Button) findViewById(R.id.restartId);
        chronometer = (Chronometer) findViewById(R.id.chrono);
        isRunning = false;

        startButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

            }
        });
        startButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                if(startButton.getText().equals("Start")){
                    if(!isRunning){
                        chronometer.setBase(SystemClock.elapsedRealtime());
                        chronometer.start();
                        isRunning = true;
                        startButton.setText("Stop");
                    }else{
                        pauseDuration = SystemClock.elapsedRealtime() - stopTime;
                        chronometer.setBase(chronometer.getBase() + pauseDuration);
                        chronometer.start();
                        startButton.setText("Stop");
                    }
                }else if(startButton.getText().equals("Stop")){
                    chronometer.stop();
                    stopTime = SystemClock.elapsedRealtime();
                    startButton.setText("Start");
                }
            }
        });

        restartButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                chronometer.setBase(SystemClock.elapsedRealtime());
                chronometer.stop();
                isRunning = false;
                if(startButton.getText().equals("Stop")){
                    startButton.setText("Start");
                }
            }
        });
    }
}

<?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"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="kerhoas.enib.fr.chrono.MainActivity">
    <!--android:background="@drawable/backgroudn"-->



    <Chronometer
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/chrono"
        android:textColor="#4169E1"
        android:textSize="@dimen/Chronometer_size"
        android:layout_centerHorizontal="true"
        android:text="@string/Start_chronometer"
        android:layout_alignParentTop="true"
        android:layout_alignBaseline="@+id/button"
        android:layout_alignBottom="@+id/button" />

    <Button
        android:text="Start"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@+id/StartId"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:layout_marginTop="41dp"
        android:id="@+id/button"
        android:background="#a2d1d4"
        android:textStyle="bold"
        android:textColor="#0da30a" />

    <Button
        android:text="Reset"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentRight="true"
        android:layout_alignParentEnd="true"
        android:id="@+id/restartId"
        android:layout_alignBaseline="@+id/button"
        android:background="#a2d1d4"
        android:textStyle="bold"
        android:textColor="#c20808" />


</RelativeLayout>