Android Studio Nilai Siswa

activity_main.xml

    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="16dp"
    android:paddingLeft="16dp"
    android:paddingRight="16dp"
    android:orientation="vertical"
    android:paddingTop="16dp"
    tools:context=".MainActivity">

            android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:orientation="vertical">
                    android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Nilai absen"
            android:textStyle="bold"
            android:layout_marginBottom="8dp"
            android:textColor="#0000FF" />
                    android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:id="@+id/nilaiabsen"
            android:text="0"
            android:inputType="number"/>
                    android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Nilai Tugas"
            android:textStyle="bold"
            android:layout_marginBottom="8dp"
            android:textColor="#0000FF" />
                    android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:id="@+id/nilaitugas"
            android:text="0"
            android:inputType="number"/>
                    android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Nilai UTS"
            android:textStyle="bold"
            android:layout_marginBottom="8dp"
            android:textColor="#0000FF" />
                    android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:id="@+id/nilaiuts"
            android:text="0"
            android:inputType="number"/>
                    android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Nilai UAS"
            android:textStyle="bold"
            android:layout_marginBottom="8dp"
            android:textColor="#0000FF" />
                    android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:id="@+id/nilaiuas"
            android:text="0"
            android:inputType="number"/>
       

MainActivity.java

package com.yusuf.dani.menghitungnilaisiswa;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;


public class MainActivity extends AppCompatActivity {
    private EditText edtabsen, edttugas, edtuts, edtuas;
    private Button btnHitung;
    private TextView txtnilai;
    private TextView txtgrade;
    private TextView txtketerangan;

    @Override    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        edtabsen = (EditText) findViewById(R.id.nilaiabsen);
        edttugas = (EditText) findViewById(R.id.nilaitugas);
        edtuts = (EditText) findViewById(R.id.nilaiuts);
        edtuas = (EditText) findViewById(R.id.nilaiuas);
        btnHitung = (Button) findViewById(R.id.tombol);
        txtnilai = (TextView) findViewById(R.id.nilaiakhir);
        txtgrade = (TextView) findViewById(R.id.nilaigrade);
        txtketerangan = (TextView) findViewById(R.id.nilaiketerangan);

        btnHitung.setOnClickListener(new View.OnClickListener() {
            @Override            public void onClick(View view) {

                // String absen = edtabsen.getText().toString();
                double a = Double.parseDouble(edtabsen.getText().toString());
                double t = Double.parseDouble(edtuts.getText().toString());
                double u = Double.parseDouble(edtuts.getText().toString());
                double ua = Double.parseDouble(edtuas.getText().toString());
                double nilai = (0.1 * a) + (0.2 * t) + (0.3 * u) + (0.4 * ua);
                txtnilai.setText("Nilai : " + nilai);

                if (nilai >= 80) {
                    txtgrade.setText("Grade A");
                } else if (nilai >= 70) {
                    txtgrade.setText("Grade B");
                } else if (nilai >= 60) {
                    txtgrade.setText("Grade C");
                } else if (nilai >= 45) {
                    txtgrade.setText("Grade D");
                } else {
                    txtgrade.setText("Grade E");
                }
                if (nilai >= 60) {
                    txtketerangan.setText("Keterangan :LULUS");
                } else {
                    txtketerangan.setText("Keterangan :TIDAK LULUS");
                }

            }
        });
    }
}