SvetofarPurvoKontrolno

package com.example.eurynomus.kontrolnosvetofar;

import android.graphics.Color;
import android.os.CountDownTimer;
import android.support.constraint.ConstraintLayout;
import android.support.v4.content.ContextCompat;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {

    ConstraintLayout mConstraintLayout;
    TextView red, yellow, green, txtGreen;
    Button button;

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

        mConstraintLayout = (ConstraintLayout) findViewById(R.id.constraintLayout);
        button = (Button) findViewById(R.id.button);
        red = findViewById(R.id.R);
        yellow = findViewById(R.id.Y);
        green = findViewById(R.id.G);
        txtGreen = findViewById(R.id.textViewGreen);




        button.setOnClickListener(new View.OnClickListener() {
            private int colorIndex = 1;
            @Override
            public void onClick(View view) {
                if(colorIndex==1){
                    red.setBackgroundResource(R.color.Red);
                    colorIndex = 0;
                }else if(colorIndex==0) {
                    yellow.setBackgroundResource(R.color.Yellow);
                    colorIndex = 2;
                }else if (colorIndex == 2){
                    green.setBackgroundResource(R.color.Green);
                    colorIndex = 3;
                    txtGreen.setBackgroundResource(R.color.Green);

                } else if (colorIndex ==3){

                    red.setBackgroundColor(0);
                    yellow.setBackgroundColor(0);
                    green.setBackgroundColor(0);
                    txtGreen.setBackgroundColor(0);
                    colorIndex = 1;
                }




            }

        });

    }

}









<?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:id="@+id/constraintLayout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity"
    >

    <Button
        android:id="@+id/button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="8dp"
        android:layout_marginTop="8dp"
        android:layout_marginEnd="8dp"
        android:layout_marginBottom="8dp"
        android:text="Button"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.902"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.049" />

    <TextView
        android:id="@+id/R"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="151dp"
        android:layout_marginTop="88dp"
        android:layout_marginEnd="201dp"
        android:text="R"
        android:textSize="30sp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.55"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <TextView
        android:id="@+id/Y"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="151dp"
        android:layout_marginTop="92dp"
        android:layout_marginEnd="201dp"
        android:text="Y"
        android:textSize="30sp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.529"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/R" />

    <TextView
        android:id="@+id/G"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="151dp"
        android:layout_marginTop="88dp"
        android:layout_marginEnd="201dp"
        android:text="G"
        android:textSize="30sp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.52"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/Y" />

    <TextView
        android:id="@+id/textViewGreen"
        android:layout_width="392dp"
        android:layout_height="151dp"
        android:layout_marginStart="3dp"
        android:layout_marginTop="183dp"
        android:layout_marginEnd="16dp"
        android:layout_marginBottom="6dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/G" />


</android.support.constraint.ConstraintLayout>