Вылетает Android приложение: Could not execute method for android:onClick

Приложение вылетает вот здесь:

 names = new String[NewArithm.index];
    for (int i = 0; i <= NewArithm.index; i++){
        names[i] = NewArithm.resultNumber[0 + i][0] + "  " + NewArithm.resultNumber[0 + i][1];
    }

Полный код MainActivity:

package home.examapp;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.EditText;
import android.widget.ListView;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {
    int firstNumber;
    int secondNumber;
    EditText editFirst;
    EditText editSecond;
    String[] names;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        editFirst = (EditText)findViewById(R.id.One);
        editSecond = (EditText)findViewById(R.id.Two);
        }
        public void onOKClick(View v) {
        firstNumber = Integer.valueOf(editFirst.getText().toString());
        secondNumber = Integer.valueOf(editSecond.getText().toString());
        //Arithmetic NewArithm = new Arithmetic();
        Arith NewArithm = new Arith();
        NewArithm.setFirst(firstNumber);
        NewArithm.setSecond(secondNumber);
        names = new String[NewArithm.index];
        for (int i = 0; i <= NewArithm.index; i++){
            names[i] = NewArithm.resultNumber[0 + i][0] + "  " + NewArithm.resultNumber[0 + i][1];
        }

        // находим список
        ListView lvMain = (ListView) findViewById(R.id.lvMain);
        // создаем адаптер
        ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,
                android.R.layout.simple_list_item_1, names);
        // присваиваем адаптер списку
        lvMain.setAdapter(adapter);
        }
}

Ошибки:

java.lang.IllegalStateException: Could not execute method for android:onClick
  at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:293)
  at android.view.View.performClick(View.java:4780)
  at android.view.View$PerformClick.run(View.java:19866)
  at android.os.Handler.handleCallback(Handler.java:739)
  at android.os.Handler.dispatchMessage(Handler.java:95)
  at android.os.Looper.loop(Looper.java:135)
  at android.app.ActivityThread.main(ActivityThread.java:5254)
  at java.lang.reflect.Method.invoke(Native Method)
  at java.lang.reflect.Method.invoke(Method.java:372)
  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
Caused by: java.lang.reflect.InvocationTargetException
  at java.lang.reflect.Method.invoke(Native Method)
  at java.lang.reflect.Method.invoke(Method.java:372)
  at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:288)
  at android.view.View.performClick(View.java:4780) 
  at android.view.View$PerformClick.run(View.java:19866) 
  at android.os.Handler.handleCallback(Handler.java:739) 
  at android.os.Handler.dispatchMessage(Handler.java:95) 
  at android.os.Looper.loop(Looper.java:135) 
  at android.app.ActivityThread.main(ActivityThread.java:5254) 
  at java.lang.reflect.Method.invoke(Native Method) 
  at java.lang.reflect.Method.invoke(Method.java:372) 
  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903) 
  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698) 
Caused by: java.lang.NullPointerException: Attempt to read from null array
  at home.examapp.MainActivity.onOKClick(MainActivity.java:41)
  at java.lang.reflect.Method.invoke(Native Method) 
  at java.lang.reflect.Method.invoke(Method.java:372) 
  at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:288) 
  at android.view.View.performClick(View.java:4780) 
  at android.view.View$PerformClick.run(View.java:19866) 
  at android.os.Handler.handleCallback(Handler.java:739) 
  at android.os.Handler.dispatchMessage(Handler.java:95) 
  at android.os.Looper.loop(Looper.java:135) 
  at android.app.ActivityThread.main(ActivityThread.java:5254) 
  at java.lang.reflect.Method.invoke(Native Method) 
  at java.lang.reflect.Method.invoke(Method.java:372) 
  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903) 
  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)

Класс Arith:

package home.examapp;
public class Arith {
    private int first;
    private int second;
    public void setFirst(int number){
        this.first = number;
    }
    public int getFirst(){
        return this.first;
    }
    public void setSecond(int number){
        this.second = number;
    }
    public int getSecond(){
        return this.second;
    }
    public int[][] resultNumber;
    public int index = 0;
    public void createResultNumber()
    {
        for (int i = 0; i <= second; i++)
            for (int j = 0; j <=second; j++)
                if(Math.pow(i, 3) + Math.pow(j, 3) <= second){
                    resultNumber[0 + this.index][0] = i;
                    resultNumber[0 + this.index][1] = j;
                    this.index++;
                }
    }
}