当用户留下空白 editText 时，如何设置 Toast 消息

Question

I have created this Random number game program here the user enter number b/w 1 to 20 and if the user enters higher number than random number, the toast message is showing and also when user enters lower number than random number. But how can I set a Toast message when user leaves a blank EditText and presses the button? Please help me.

package com.example.higherlowergame;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

import java.util.Random;

public class MainActivity extends AppCompatActivity
{
    int randnum;
    EditText e;

    public void guess(View view)
    {
        int guessnum= Integer.parseInt ( e.getText ().toString () );

        if(e == null)
        {
            Toast.makeText ( this , "Enter a num" , Toast.LENGTH_SHORT ).show ();
        }

        if(guessnum > randnum)
        {
            Toast.makeText ( this , "guess lower num" , Toast.LENGTH_SHORT ).show ();
        }
        else if (guessnum < randnum)
        {
            Toast.makeText ( this , "guess upper num" , Toast.LENGTH_SHORT ).show ();
        }
        else
        {
            Toast.makeText ( this , "yehh Thts the right num ! and try again for new num" , Toast.LENGTH_LONG ).show ();

            Random random=new Random (  );
            randnum=random.nextInt (20)+ 1;
        }
    }

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

        e=(EditText)findViewById ( R.id.et );

        Random random=new Random (  );
        randnum=random.nextInt (20) + 1;
    }
}

Answer 1

When pressing the button, Check for Edittext length greater than zero then continue to the function.

Try below code,

  public void guess(View view)
    {
    if (e.getText().toString().length()==0) {
           Toast.makeText ( this , "YOUR MESSAGE FOR EMPTY" Toast.LENGTH_SHORT ).show();
           return;
       }
 }