错误：（73,59）错误：不是封闭的类：Mari

Question

我正在尝试在我的Android应用程序中创建一个新的Mari.java并在其上调用execute方法但它无效。我该如何解决？

Kelima.java

package com.example.dell.ayongaji;
import android.content.DialogInterface;
import android.content.Intent;
import android.media.ExifInterface;
import android.os.Bundle;
import android.support.v7.app.AlertDialog;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.RadioButton;
import android.widget.RadioGroup;
import android.widget.Toast;
public class Kelima extends AppCompatActivity {

AlertDialog.Builder builder;
RadioGroup radiogroup;
//deklarasi var or obj

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

    getSupportActionBar().setTitle("OneDayOneHuruf");
    //getSupportActionBar().setSubtitle("Belajar di okedroid.com");

    //radiogroup inisialisasi
    radiogroup = (RadioGroup) findViewById(R.id.radioGroup);


}

//Memilih RadioButton

public void onRadioButton(View view) {

    Boolean checked = ((RadioButton) view).isChecked();


    switch (view.getId()) {
        case R.id.radioButton:
            if (checked)
                jawabanSalah();
            break;

        case R.id.radioButton2:
            if (checked)
                jawabanSalah();
            break;
        case R.id.radioButton3:
            if (checked)
                tampilDialog();
            break;
        case R.id.radioButton4:
            if (checked)
                jawabanSalah();
            break;
    }


}

//menampilkan dialog
public void tampilDialog() {

    builder = new AlertDialog.Builder(this);
    builder.setCancelable(false);
    builder.setTitle("Selamat !!!");
    builder.setMessage("Jawaban anda benar");
    builder.setPositiveButton("OKE", new DialogInterface.OnClickListener() {
        @Override
        public void onClick(DialogInterface dialogInterface, int i) {
            Intent ii =  new Intent (Kelima.this, Mari.this);
            startActivity(ii);
        }
    });

    builder.setNegativeButton("ULANGI", new DialogInterface.OnClickListener() {
        @Override
        public void onClick(DialogInterface dialogInterface, int i) {
            radiogroup.clearCheck();
        }
    });

    builder.create().show();

}
//menampilkan toast text jawaban salah
public void jawabanSalah(){

    Toast.makeText(this, "Jawaban anda Salah", Toast.LENGTH_SHORT).show();

}
}

Mari.Java

package com.example.dell.ayongaji;
import android.os.Bundle;
import android.support.annotation.IdRes;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.content.DialogInterface;
import android.support.v7.app.AlertDialog;
import android.content.Intent;



public class Mari extends AppCompatActivity {
TextView ff;
Button metu;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.mari);
    ff=(TextView)findViewById(R.id.ggg);
    metu=(Button)findViewById(R.id.button) ;
    getSupportActionBar().setTitle("OneDayOneHuruf");
    metu.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View arg0) {

            AlertDialog.Builder alertexit = new AlertDialog.Builder(
                    Mari.this);

            alertexit
                    .setMessage("Apakah Anda Akan Keluar Dari Aplikasi ini?")
                    .setIcon(android.R.drawable.ic_dialog_alert)
                    .setTitle("Keluar")
                    .setCancelable(false)
                    .setPositiveButton("ya",
                            new AlertDialog.OnClickListener() {
                                @Override
                                public void onClick(DialogInterface arg0,
                                                    int arg1) {
                                    System.exit(0);
                                }
                            })
                    .setNegativeButton("tidak",
                            new AlertDialog.OnClickListener() {

                                @Override
                                public void onClick(DialogInterface dialog,
                                                    int which) {
                                    dialog.cancel();
                                }
                            });
            AlertDialog a = alertexit.create();
            a.show();
        }
    });

}
}