java - シンボルが見つかりません: メソッド setCurrent(Kalkulator)

Question

メイン メニューを使用するアプリを作成できるように、Java ファイルを接続しようとしていますが、何をしてもこのエラーは解決しません。これが私のコードです：Zakat.java

import javax.microedition.midlet.*;
import javax.microedition.lcdui.*;

public class Zakat extends MIDlet
{
private Display display;
public FormLoading FormLoading;
public Keluar Keluar;
public MenuUtama MenuUtama;
public Pengenalan Pengenalan;
public Kalkulator Kalkulator;
public About About;
public Profil Profil;
//public CanvasAwal canvasAwal;

    public Zakat()
{
    display = Display.getDisplay(this);
            FormLoading = new FormLoading(this);
            Keluar = new Keluar(this);
            MenuUtama = new MenuUtama(this);
            Pengenalan = new Pengenalan(this);
            Kalkulator = new Kalkulator(this);
            About = new About(this);
            Profil = new Profil(this);
            //canvasAwal = new CanvasAwal(this);


}

public void startApp()
{
    Display.getDisplay(this).setCurrent(FormLoading);

}
public void pauseApp()
{
}
public void destroyApp(boolean b)
{
}



}

MenuUtama.java

import java.io.IOException;
import javax.microedition.midlet.*;
import javax.microedition.lcdui.*;

class MenuUtama extends List implements CommandListener
{
public Zakat app;
Ticker tc;
public MenuUtama(Zakat app)

{
    super("Menu Utama",List.IMPLICIT);
    this.app = app;
    Image img=null;
    Image img1=null;
    Image img2=null;
    try
    {
    img = Image.createImage("/icon1.png");
    }
    catch(Exception e)
    {
    }
    append("Pengenalan Zakat",img);
    append("Kalkulator",img);
    append("About",img);
    append("Profil",img);
    append("Keluar",img);


    addCommand(new Command("Pilih",Command.OK,0));
    addCommand(new Command("Keluar",Command.EXIT,0));
    tc = new Ticker ("Silahkan Pilih");
    setTicker(tc);
    setCommandListener(this);

}

public void commandAction (Command c, Displayable d)
{
switch(getSelectedIndex())
    {
        case 0:
            Display.getDisplay(app).setCurrent(app.Pengenalan);
            break;
        case 1:
            Display.getDisplay(app).setCurrent(app.Kalkulator);
            break;
        case 2:
            Display.getDisplay(app).setCurrent(app.About);
            break;
        case 3:
            Display.getDisplay(app).setCurrent(app.Profil);
            break;
        case 4:
            Display.getDisplay(app).setCurrent(app.Keluar);
            break;
    }

    switch( c.getCommandType())
    {
        case Command.EXIT:
            Display.getDisplay(app).setCurrent(app.Keluar);
            break;
    }
}
}

計算機.java

import javax.microedition.midlet.*;
import javax.microedition.lcdui.*;
import java.io.IOException;

public class Kalkulator extends MIDlet implements CommandListener,ItemCommandListener
{
Zakat app;
private Command cmdHitung = new Command("Hitung",Command.ITEM,1);
private Command exitCommand = new Command("Kembali",Command.EXIT,1);
private Display display;
private Form form = new Form("kalkulator");
private TextField var;
private TextField hasil;
public Kalkulator(Zakat app)
{
    var = new TextField("Penghasilan selama 1 Tahun",null,12,TextField.NUMERIC);
    hasil = new TextField("Zakat yang harus dibayarkan",null, 12 ,TextField.NUMERIC);   
    form.append(var);
    form.append(hasil);
    form.setCommandListener(this);
}

public void startApp() 
{
    if(display==null)
    {
        display = Display.getDisplay(this);
        display.setCurrent(form);
    }
}


public void pauseApp()
{
}

public void destroyApp(boolean unconditional) 
{
}

public void commandAction (Command c, Displayable d)
{
    switch (c.getCommandType())
    {
        case Command.EXIT:
        Display.getDisplay(app).setCurrent(app.MenuUtama);
        break;
    }
}

public void commandAction(Command c, Item item) 
{
    if(c.equals(this.cmdHitung))
    {
    int hsl = Integer.parseInt(var.getString()) / 40;
    hasil.setString(Integer.toString(hsl));
    }
}
}

助けてください、そして前に感謝します。