如果我的应用程序中有空白字段，它会崩溃（java、android）

Question

I have tried a few things that I searched here but they didn't work. I tried a try/catch method and many if-functions it's crazy. I basically just want to display a message in a text view box when nothing is entered to tell the user to enter something. This is basically just an application to display the average that person has run for a certain amount of km.

Here is my code below:

import android.content.Intent;
import android.os.Bundle;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

import androidx.appcompat.app.AppCompatActivity;

import java.text.DecimalFormat;

public class MainActivity extends AppCompatActivity {

    protected void onCreate(Bundle savedInstanceState) {
       super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //Initiating and referencing for Calculate Button
        Button button = findViewById(R.id.button);
        //onClickListener for the Calculate Button
        button.setOnClickListener(v -> {
            //Variables to calculate average runtime
            final EditText totalHours   = findViewById(R.id.totalHours);
            final EditText totalMinutes = findViewById(R.id.totalMins);
            double kilometer = 42.2;
            //Creating a variable to display an error message
            final TextView errorMsg = findViewById(R.id.errorMsg);
            //Checking to see if anything was entered into the editText fields -- THE ISSUE I HAVE
            if(totalHours.length() < 0 || totalMinutes.length() < 0){
             errorMsg.setText(R.string.nothingEnteredError);
            } else {
                //Parse the input from the user (from text to double)
                double Hours = Integer.parseInt(totalHours.getText().toString());
                double Minutes = Integer.parseInt(totalMinutes.getText().toString());
                //Checking requirements - not more than 10 hours entered and not more than 59 minutes entered.
                if (Hours > 10) {
                    errorMsg.setText(R.string.errorOnHours);
                } else if (Minutes > 59) {
                    errorMsg.setText(R.string.errorOnMinutes);
                } else {
                    //calculating average runtime
                    double average = ((Hours * 60) + Minutes) / kilometer;
                    //setting the format to 0.00
                    DecimalFormat aForm = new DecimalFormat("0.00");
                    //creating a string version of average
                    String sAverage = Double.toString(average);
                    //Text to display in the second activity
                    String textToSet = String.format("Your average time to run one kilometer was %s", aForm.format(average));
                    //creating net intent to start the results page activity
                    Intent i = new Intent(MainActivity.this, resultsPage.class);
                    //adding textToSet to the results activity
                    i.putExtra("key", textToSet);
                    i.putExtra("average", sAverage);
                    //Starting results activity
                    startActivity(i);
                }
            }
        });
    }
}```

Answer 1

totalHours.length() < 0 || totalMinutes.length() < 0

Here you only check if the length is lower than zero. I would try changing this so it checks for length <= 0