Why my volume variable stays 10 at all the time in my TV class

[nvthai]

The volume is set to be at 10 in my TV class and you should be able to increment and decrement it by 1 ( i used 1 for increment ) and -1 for decrement but if you increment it by one you get 11 but when you try it again and increment it you still get 11 instead of 12 here is the code \[code\]public class TV{ private boolean flag = false; private int ch; private int vol = 10; public TV(boolean onOffSwitch, int channel, int volume) { this.setFlag(onOffSwitch); this.setCh(channel); this.setVol(volume); } public void setFlag(boolean onOffSwitch) { flag = onOffSwitch; } public boolean getFlag() { return flag; }// End of getFlag public void setCh (int newChannel) { ch = (newChannel>=99) ? 99 : ((newChannel<0) ? 1 : newChannel); }//end of setCh public int getCh () { return ch; }// End of getCh public void setVol(int newVolume) { if(newVolume >= 20) { vol = 20; }else if(newVolume < 0) { vol = 0; } }// End of SetVolume public void incrementVolume() { vol = vol + 1; } public void decrementVolume() { vol--; } public int getVol() { return vol; }// ENd of getVolume public String toString() { String onOrOff = flag ? "ON" : "OFF"; return String.format("%s :%s\n%s:%d\n%s :%d","TV is switched",onOrOff,"TV channel",ch,"TV volume",vol); }}// End of TV class\[/code\]my test class \[code\]import java.util.Scanner;public class TvTest{ public static void main (String[] args) { String x; boolean y = true; boolean tvStatus = false; int chan; int volu; boolean remoteControlContinue = true; Scanner input = new Scanner(System.in); TV tv2 = new TV(false,2,10); // Print out the current status of our TV System.out.print(tv2); System.out.println();// print out an empty line do { do { System.out.println("Enter exit to stop using the remote !"); System.out.print("Turn TV On or Off ?"); x = input.next(); if(x.equalsIgnoreCase("exit")) { y = false; } if(x.equalsIgnoreCase("on")) { tvStatus = true; //y = false; remoteControlContinue = false; }else if(x.equalsIgnoreCase("off")) { tvStatus =false; remoteControlContinue = true; System.out.println(tv2); }// End of if }while (remoteControlContinue); // Ask for Channel System.out.print("Change the Channel to : "); chan = input.nextInt(); System.out.print("Increase the volume by 1 or Decrease by -1 : "); volu = input.nextInt(); TV tv1 = new TV(tvStatus,chan,volu); if(volu == 1) { tv1.incrementVolume(); }else if (volu == -1) { tv1.decrementVolume(); } System.out.println(tv1); }while(y); }}// ENd of TvTes\[/code\]here is the result i get pay attention to volume value please in the result\[code\]TV is switched :OFFTV channel:2TV volume :10Enter exit to stop using the remote !Turn TV On or Off ?onChange the Channel to : 55Increase the volume by 1 or Decrease by -1 : 1TV is switched :ONTV channel:55TV volume :11Enter exit to stop using the remote !Turn TV On or Off ?onChange the Channel to : 56Increase the volume by 1 or Decrease by -1 : 1TV is switched :ONTV channel:56TV volume :11Enter exit to stop using the remote !Turn TV On or Off ?\[/code\]