CounterActivity.java

public class CounterActivity extends AppCompatActivity {

    private int nilaiSkor = 0;
    private TextView tvCounter;

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

        tvCounter = findViewById(R.id.tv_counter);
        Button btnTambah1 = findViewById(R.id.btn_tambah1);
        Button btnTambah2 = findViewById(R.id.btn_tambah2);
        Button btnTambah3 = findViewById(R.id.btn_tambah3);
        Button btnReset = findViewById(R.id.btn_reset);


        btnTambah1.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                nilaiSkor += 1;
                ubahSkor(nilaiSkor);
            }
        });

        btnTambah2.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                nilaiSkor += 2;
                ubahSkor(nilaiSkor);
            }
        });
        btnTambah3.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                nilaiSkor += 3;
                ubahSkor(nilaiSkor);
            }
        });
        btnReset.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                nilaiSkor = 0;
                ubahSkor(nilaiSkor);
            }
        });
    }

    private void ubahSkor(int skor) {
        tvCounter.setText(String.valueOf(skor));
    }
}