关于android：没有调用Else条件

Else condition is not being called

我有一个if条件来检查edittext是否为空，如果它是空的，则引发警报。但是当我向edittext输入一些值时，它也会给我提醒

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package com.example.calculator;

import android.app.Activity;
import android.app.AlertDialog;
import android.content.Context;
import android.content.DialogInterface;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.inputmethod.InputMethodManager;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

public class Calci extends Activity {
TextView t1;
EditText e1, e2;
Button add, sub, mul, div;
Context c=this;

String b, a;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_calci);
e1 = (EditText) findViewById(R.id.EditText01);
e2 = (EditText) findViewById(R.id.EditText02);
add = (Button) findViewById(R.id.add);
sub = (Button) findViewById(R.id.sub);
mul = (Button) findViewById(R.id.mul);
div = (Button) findViewById(R.id.div);
t1 = (TextView) findViewById(R.id.textView1);
a = e1.getText().toString();
b = e2.getText().toString();
add.setOnClickListener(new View.OnClickListener() {

@Override
public void onClick(View arg0) {
if (a.equals("") || b.equals("")){

AlertDialog.Builder a1 = new AlertDialog.Builder(c);
// Setting Dialog Title
a1.setTitle("Alert Dialog");
// Setting Dialog Message
a1.setMessage("PLEASE ENTER SOMETHING");
a1.setPositiveButton("yes",
new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog,
int button1) {
// if this button is clicked, close
// current activity
dialog.cancel();
}
});

// Showing Alert Message
AlertDialog alertDialog = a1.create();
a1.show();

} else {
Log.d("sadasd","msg");
int result = Integer.parseInt(a) + Integer.parseInt(b);
t1.setText(Integer.toString(result));
// InputMethodManager imm = (InputMethodManager)getSystemService(
// Context.INPUT_METHOD_SERVICE);
// imm.hideSoftInputFromWindow(add.getWindowToken(), 0);
}

}

});
}
}

我有一个if条件，检查edittext是否为空，如果它是空的，则引发警报。但是当我向edittext输入一些值时，它也会给我警报。