Ketlle

public class Kettle {
 private int volume;
 public Kettle(int water) {
  volume =water;
  System.out.println("This Kettle Volume is "+volume);
 }
 public int heatingwater (int needwater){
  int actualwater=0;
  
  if(needwater>volume){
   System.out.println("Too much!");
  }
  else{
   actualwater=needwater-2;
   if(actualwater<=0){
    System.out.println("need more water!");
   }
   else{
    System.out.println("heating"+" "+actualwater+"L water");
   }
   
  }  
  return actualwater;
 }
}

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import java.util.Scanner;

public class cl {

public static void main(String[] args) {   Scanner in =new Scanner(System.in);

System.out.println("please input Kettle volume：");

int a1 =in.nextInt();

System.out.println("please input needwater：");

int a2 =in.nextInt();

Kettle k1 =new Kettle(a1);

k1.heatingwater(a2);

}

}