Java: contoh inheritance

Nilai.java

public class Nilai extends Grade{

	double presensi ;
	double uts;
	double uas;
	double tugas;
	
	public Nilai(){
		this.presensi = 0;
		this.uts = 0;
		this.uas = 0;
		this.tugas = 0;
		super.nilaiAkhir = 0;
	}
	
	public void setPresensi(double presensi){
		this.presensi=presensi;
	}	
	
	public void setUts (double uts){
		this.uts=uts;
	}
	
	public void setUas (double uas){
		this.uas=uas;
	}
	
	public void setTugas (double tugas){
		this.tugas=tugas;
	}
	public void setNilaiAkhir(){
		double n = 0.0;
		n = this.presensi + this.uts + this.uas + this.tugas;
		this.nilaiAkhir = n;
	}
	public get

	
}