当按下按钮时未输入任何内容时，Android应用程序崩溃

Question

Trust you are well. You helped a fellow member out for a query ( Android app crashes when nothing is entered and button is pressed ) on App crashing when nothing is entered in the EditText field. I am having the same issue but my application still crashes when I input your code correctly.

I would appreciate if you could look at my code below and inform me what I may have to change to make it work. I am a confused with what the num1 was being used for, and as you can see I can't change num1 into test as it is being used for my onClick to generate an email.

Thank you in advance.

public void calculateTS(View v){
    String status;
    test = Double.parseDouble(edtResult.getText().toString());
    String result = String.format("%.2f", test);
    Log.d("MyActivity", result);

    EditText editText = (EditText)findViewById(R.id. edtResult);
    Double num1 = 0.0;
    final String myStr = editText.getText().toString();
    if (!myStr.isEmpty())
    {
        num1 = Double.parseDouble(myStr);
    }
    else
    {
        Toast.makeText(getApplicationContext(), getResources().getString(R.string.noinput),
                Toast.LENGTH_LONG).show();
        if( test < 20.5) {
            status = "Poor";
        } else if (test >= 20.5 && test < 50.5){
            status = "Average";
        } else if (test >= 50.5 && test < 100.0) {
            status ="Well Done"; }
        AlertDialog alertDialog = new AlertDialog.Builder(this).create();
        alertDialog.setTitle("Result Feedback...");
        alertDialog.setMessage(status);
        alertDialog.setButton("Acknowledged", new DialogInterface.OnClickListener() {
            public void onClick(DialogInterface dialog, int which) {
                if(test< 20.5)){
                    String email = "test@test.com";
                    String subject = "Feedback";
                    String message = "Hello,\n\nTest.";
                    final Intent emailIntent = new Intent( android.content.Intent.ACTION_SEND );
                    emailIntent.setType( "plain/text" );
                    emailIntent.putExtra( android.content.Intent.EXTRA_EMAIL, new String[] { email } );
                    emailIntent.putExtra( android.content.Intent.EXTRA_SUBJECT, subject );
                    emailIntent.putExtra( android.content.Intent.EXTRA_TEXT, message );

                    startActivityForResult( Intent.createChooser( emailIntent, "Send Mail..."), 1234);
                }
            }
        });

        alertDialog.show();
    }

Answer 1

It looks like you have your cases mixed up. If the field is empty, simply Toast that the field is empty and do nothing. If the field is not empty, then do all the other stuff.

//This should be a member variable
Double test;    

public void calculateTS(View v){
    String status;


    EditText editText = (EditText)findViewById(R.id.edtResult);
    Double num1 = 0.0;
    final String myStr = editText.getText().toString();
    if (myStr.isEmpty())
    {
        //num1 = Double.parseDouble(myStr); //looks like this is not used?

        Toast.makeText(getApplicationContext(), getResources().getString(R.string.noinput),
                Toast.LENGTH_LONG).show();
    }
    else
    {
        test = Double.parseDouble(myStr);
        String result = String.format("%.2f", test);
        Log.d("MyActivity", result);

        if( test < 20.5) {
            status = "Poor";
        } else if (test >= 20.5 && test < 50.5){
            status = "Average";
        } else if (test >= 50.5 && test < 100.0) {
            status ="Well Done"; }
        AlertDialog alertDialog = new AlertDialog.Builder(this).create();
        alertDialog.setTitle("Result Feedback...");
        alertDialog.setMessage(status);
        alertDialog.setButton("Acknowledged", new DialogInterface.OnClickListener() {
            public void onClick(DialogInterface dialog, int which) {
                if(test< 20.5)){
                    String email = "test@test.com";
                    String subject = "Feedback";
                    String message = "Hello,\n\nTest.";
                    final Intent emailIntent = new Intent( android.content.Intent.ACTION_SEND );
                    emailIntent.setType( "plain/text" );
                    emailIntent.putExtra( android.content.Intent.EXTRA_EMAIL, new String[] { email } );
                    emailIntent.putExtra( android.content.Intent.EXTRA_SUBJECT, subject );
                    emailIntent.putExtra( android.content.Intent.EXTRA_TEXT, message );

                    startActivityForResult( Intent.createChooser( emailIntent, "Send Mail..."), 1234);
                }
            }
        });

        alertDialog.show();
    }