abstract method in jav code example

Example 1: how to make abstract method in java

public abstract class Account {		//abstract class //perent class
    protected int accountNumber;
    protected Customer customerObj;
    protected double balance;
  	//constructor
  	public Account(int saccountNumber, Customer scustomerObj,double sbalance){
        accountNumber = saccountNumber;
        customerObj = scustomerObj;
        balance = sbalance;
    }
  	// abstract Function
    public abstract boolean withdraw(double amount); 
}   

public class SavingsAccount extends Account { // child class
    private double minimumBalance;
  	// constructor
    public SavingsAccount(int saccountNumber, Customer scustomerObj, double sbalance, double sminimumBalance) {
        super(saccountNumber, scustomerObj, sbalance);
        minimumBalance = sminimumBalance;
    }
	// Implementation of abstract function in child class
    public boolean withdraw(double amount) {
        if (balance() > minimumBalance && balance() - amount > minimumBalance) {
            super.setBalance(balance() - amount);
            return true;
        } else {
            return false;
        }
    }
}

Example 2: java abstract

abstract class Pesan {
   public void success() {
     System.out.println("Mobil Berhasil Dibeli");
   }
   
   public void error() {
     System.out.println("Uang Anda Tidak Cukup");
   }
}
 
class Car extends Pesan {
    protected String nama = "toyota supra";
    protected String warna = "merah";
    protected int harga = 2000000000;
    protected String brand = "toyota";
}
 
class ShowRoom extends Car {
  protected String namaShowroom = "Catur Sentosa Raya";
  protected String alamatShowroom = "Jl.siliwangin kec pancoranmas kota depok 16436";
}
 
class Pembeli extends ShowRoom {
    protected String namaPembeli = "anto jayabaya";
    protected String alamatPembeli = "jl.swadaya rt.01/rw.04 no.112 kec pancoranmas kota depok";
    protected int saldoPembeli = 50000000;
}
 
class BeliMobil extends Pembeli {
 
 public BeliMobil(String nama, String warna, int harga, String brand, String nsr, String asr, String np, String ap, int sdp) {
    super();
    
    super.nama = nama;
    super.warna = warna;
    super.harga = harga;
    super.brand = brand;
    super.namaShowroom = nsr;
    super.alamatShowroom = asr;
    super.namaPembeli = np;
    super.alamatPembeli = ap;
    super.saldoPembeli = sdp;
 }
    
void getResult(String nama, String warna, int harga, String brand, String np, String ap) {
    
     if(super.harga > super.saldoPembeli) {
       System.out.println("=======================");
       super.error();
       System.out.println("=======================");
     } else {
       System.out.println("=======================");
       super.success();
       System.out.println("=======================");
       System.out.println("");
       System.out.println("=======================");
       System.out.println("Jenis Mobil");
       System.out.println("=======================");
       System.out.println("");
       System.out.println("Nama Mobil:" + nama);
       System.out.println("Warna Mobil:" + warna);
       System.out.println("Harga Mobil:" + harga);
       System.out.println("Brand Mobil:" + brand);
       System.out.println("");
       System.out.println("=======================");
       System.out.println("Nama Pembeli Mobil");
       System.out.println("=======================");
       System.out.println("Nama Pembeli:" + np);
       System.out.println("Nama Pembeli:" + ap);
     }
  }
    
 public static void main(String[] args) {
   BeliMobil beli = new BeliMobil("avanza", "hitam", 128000000, "toyota", "Jaya Mobil", "Jakarta", "Anton", "Depok", 228000000);
   beli.getResult(beli.nama, beli.warna, beli.harga, beli.brand, beli.namaPembeli, beli.alamatPembeli);
  }
}