Question

need basic default constructor , and shoed an example too

s0. write the class Battery and it has
s1. a data for the battery capacity (that is similar to myBalance of the BankAccount class.)
s2. a parameterized constructor: public Battery(double amount)
s3. a drain mutator
s4. a change mutator
s5. a getRemainingCapacity accessor

Need to run this tester -

public class BatteryTester{
public static void main(String[] args) {
Battery autoBattery = new Battery(2000); //call default constructor
System.out.println("1. battery capacity is " + autoBattery.getRemainingCapacity() + " mAh.");
autoBattery.drain(100);
System.out.println("2. battery capacity is " + autoBattery.getRemainingCapacity() + " mAh.");
autoBattery.charge();
System.out.println("3. battery capacity is " + autoBattery.getRemainingCapacity() + " mAh.");
}
}

Similar Example-

/**
BankAccount class
*/
public class BankAccount { //s0
   private double myBalance; //s1
   public BankAccount() {myBalance = 0.00;}//s2
   /**
   My parameterizedconstructor
   @param initial amount
   */
   public BankAccount(double pAmount){myBalance = pAmount;} //s3
   /**
   My mtator to deposit $$
   @param deposit amount
   */
   public void deposit(double pAmount){myBalance += pAmount;} //s4
   /**
   My accessor getBalnace
   @return balance
   */
   public double getBalance(){return myBalance;} //s5

Answer 1

If you have any problem with the code feel free to comment.

Program

class Battery {
   // instance variables
   private double capacity;
   private double fullCapacity;// for holding full capacity of battery

   public Battery(double capacity) {// constructor
       this.capacity = capacity;
       fullCapacity = capacity;
   }

   public void drain(double i) {
       if (i < capacity)// checking if the drainage value is less than the capacity
           capacity -= i;
       else// turn capacity to zero
           capacity = 0;
   }

   public void charge() {
       capacity = fullCapacity;// charging the capacity to fullCapacity
   }

   public double getRemainingCapacity() {
       return capacity;// returning capacity value
   }

}

public class Test {// driver class
   public static void main(String[] args) {
       Battery autoBattery = new Battery(2000); // call default constructor
       System.out.println("1. battery capacity is " + autoBattery.getRemainingCapacity() + " mAh.");
       autoBattery.drain(100);
       System.out.println("2. battery capacity is " + autoBattery.getRemainingCapacity() + " mAh.");
       autoBattery.charge();
       System.out.println("3. battery capacity is " + autoBattery.getRemainingCapacity() + " mAh.");
   }
}

Output