'class Button' has no member named 'init'

// Include Libraries
#include "Arduino.h"
#include "Button.h"
// Pin Definitions
#define REFLECTIVEIR_PIN_COLL A3
#define REFLECTIVEIR_PIN_COLL_M A5
// object initialization
Button ReflectiveIR(REFLECTIVEIR_PIN_COLL);
Button ReflectiveIR_M(REFLECTIVEIR_PIN_COLL_M);
// define vars for testing menu
const int timeout = 10000; //define timeout of 10 sec
char menuOption = 0;
long time0;

#include <Servo.h>
#define redpin 5
#define bluepin 6
#define greenpin 7
#define redpin_M 8
#define bluepin_M 9
#define greenpin_M 10
int plasticsensor=A0;
int anothersensor=A2;
int metalsensor=A4;
int metalsensor_M=A6;

Servo myservo; // create servo object to control a servo
Servo myservo_M; // create servo object to control a servo
// twelve servo objects can be created on most boards

int pos = 165; // variable to store the servo position
int pos_M = 158; // variable to store the servo position

void setup() {
myservo.attach(11); // attaches the servo on pin 9 to the servo object
myservo_M.attach(12); // attaches the servo on pin 9 to the servo object
pinMode(redpin,OUTPUT);
pinMode(bluepin,OUTPUT);
pinMode(greenpin,OUTPUT);
//metal sensor
pinMode(redpin_M,OUTPUT);
pinMode(bluepin_M,OUTPUT);
pinMode(greenpin_M,OUTPUT);

pinMode(plasticsensor,INPUT_PULLUP);
pinMode(metalsensor,INPUT_PULLUP);
pinMode(anothersensor,INPUT_PULLUP);
pinMode(metalsensor_M,INPUT_PULLUP);
Serial.begin(9600);
analogWrite(redpin,255);
analogWrite(bluepin,0255);
analogWrite(greenpin,255);
analogWrite(redpin_M,255);
analogWrite(bluepin_M,0255);
analogWrite(greenpin_M,255);
ReflectiveIR.init();
ReflectiveIR_M.init();
}

void loop() {

int sensor_read=digitalRead(plasticsensor);
int sensor_read_m=digitalRead(metalsensor);
int sensor_read_mm=digitalRead(metalsensor_M);
Serial.println("plastic sensor");
Serial.println(sensor_read);
Serial.println("metal sensor");
Serial.println(sensor_read_m);
Serial.println(sensor_read_mm);

bool ReflectiveIR_Val = ReflectiveIR.read();
bool ReflectiveIR_Val_M = ReflectiveIR_M.read();
//Plastic bin
if((sensor_read==0)&&(sensor_read_m!=1)){
for (pos = 160; pos >= 90; pos -= 1) { // goes from 0 degrees to 180 degrees
// in steps of 1 degree
myservo.write(pos); // tell servo to go to position in variable 'pos'
delay(1); // waits 15ms for the servo to reach the position
}
analogWrite(redpin,255);
analogWrite(bluepin,0);
analogWrite(greenpin,255);
delay(2500);
for (pos = 90; pos <= 160; pos += 1) { // goes from 180 degrees to 0 degrees
myservo.write(pos); // tell servo to go to position in variable 'pos'
delay(1); // waits 15ms for the servo to reach the position

     }
 analogWrite(redpin,0);
 analogWrite(bluepin,0);
  analogWrite(greenpin,0);

}

else if(ReflectiveIR_Val==1){ //checking the volume of the trash
 analogWrite(redpin,0);
analogWrite(bluepin,255);
analogWrite(greenpin,255);

}

else{
  // goes from 180 degrees to 0 degrees
myservo.write(pos);              // tell servo to go to position in variable 'pos'
                       // waits 15ms for the servo to reach the position


analogWrite(redpin,255);
analogWrite(bluepin,255);
analogWrite(greenpin,255);

}

//metal sensor

  if(sensor_read_mm==1){

for (pos_M = 160; pos_M >= 90; pos_M -= 1) { // goes from 0 degrees to 180 degrees
// in steps of 1 degree
myservo_M.write(pos_M); // tell servo to go to position in variable 'pos'
delay(1); // waits 15ms for the servo to reach the position
}
analogWrite(redpin_M,255);
analogWrite(bluepin_M,0);
analogWrite(greenpin_M,255);
delay(2500);
for (pos_M = 90; pos_M <= 160; pos_M += 1) { // goes from 180 degrees to 0 degrees
myservo_M.write(pos_M); // tell servo to go to position in variable 'pos'
delay(1); // waits 15ms for the servo to reach the position

 }
  analogWrite(redpin_M,0);
  analogWrite(bluepin_M,0);

analogWrite(greenpin_M,0);

}

else if(ReflectiveIR_Val_M==1){
analogWrite(redpin_M,0);
analogWrite(bluepin_M,255);
analogWrite(greenpin_M,255);

}

else{
// goes from 180 degrees to 0 degrees
myservo_M.write(pos_M); // tell servo to go to position in variable 'pos'
// waits 15ms for the servo to reach the position

analogWrite(redpin_M,255);
analogWrite(bluepin_M,255);
analogWrite(greenpin_M,255);

}

}

Your post was MOVED to its current location as it is more suitable.

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Where did you get the Button library from ?

in google

More details please

Can you post a link to where you got it from ?