make sure the edittext is not empty

Question

I want to make sure that the fields are not empty before the submit button is pressed to stop the application from crashing.

this is my code

package com.alrabei.edcalactivity;

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

public class edcalactivity extends AppCompatActivity {

    EditText firstNumber;
    EditText secondNumber;
    EditText thirdnum;
    EditText forthnum;
    TextView showresult;
    Button buadd1;


    double num1,num2,num3,num4,sum1,sum2,sum3,TotalBuy;

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

        firstNumber = (EditText)findViewById(R.id.s1);
        secondNumber = (EditText)findViewById(R.id.p1);
        thirdnum = (EditText)findViewById(R.id.s2);
        forthnum = (EditText)findViewById(R.id.p2);
        showresult = (TextView)findViewById(R.id.result);
        buadd1 = (Button)findViewById(R.id.bu1);



        buadd1.setOnClickListener(new View.OnClickListener() {



          public void onClick(View v) {


              num1 = Double.parseDouble(firstNumber.getText().toString());
              num2 = Double.parseDouble(secondNumber.getText().toString());
              num3 = Double.parseDouble(thirdnum.getText().toString());
              num4 = Double.parseDouble(forthnum.getText().toString());





              if((firstNumber.getText().length()>0) && (secondNumber.getText().length()>0) && (thirdnum.getText().length()>0) && (forthnum.getText().length()>0))
              {
                  sum1 = num1 + num3;
                  TotalBuy = (num1 * num2) + (num3 * num4);
                  // sum2 = num2 + num4;
                  // sum3 = sum2 / sum1;
                  sum3 = TotalBuy / sum1;

                  showresult.setText(Double.toString(sum3));
              }
              else{
                  showresult.setText("Error");
              }



           }

        });



    }



}

and this is the xml file

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:gravity="center"
    android:orientation="vertical"
    tools:context="com.alrabei.edcalactivity">


    <LinearLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:gravity="center"
        android:orientation="vertical">

        <TextView
            android:id="@+id/textView5"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:text="العدد السابق" />

        <EditText
            android:id="@+id/s1"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:ems="10"
            android:inputType="number" />

        <TextView
            android:id="@+id/textView9"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="السعر:" />

        <EditText
            android:id="@+id/p1"
            android:layout_width="171dp"
            android:layout_height="wrap_content"
            android:ems="10"
            android:inputType="number|numberDecimal" />

    </LinearLayout>

    <LinearLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:gravity="center"
        android:orientation="vertical">

        <TextView
            android:id="@+id/textView8"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="الجديد" />

        <EditText
            android:id="@+id/s2"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:ems="10"
            android:inputType="number" />

        <TextView
            android:id="@+id/textView10"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="القيمة:" />

        <EditText
            android:id="@+id/p2"
            android:layout_width="173dp"
            android:layout_height="wrap_content"
            android:ems="10"
            android:inputType="number|numberDecimal" />

    </LinearLayout>

    <Button
        android:id="@+id/bu1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Button" />

    <TextView
        android:id="@+id/result"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="TextView"
        android:maxLength="5"
        />

</LinearLayout>

i did an if statement to make sure that the user will enter a number in the edittext but it doesn't work .. can you help me what is wrong with the code..

Answer 1

You do the check after parsing the numbers. That way the Double.parseDouble() will already try to access the empty string before you check for it being empty.

You need to wrap the if-statement around the whole content of the onClick() function.

Answer 2

First check whether an EditView is empty or not:

if(!firstNumber.getText().toString().trim().equals("")){
//To Do
    num1 = Double.parseDouble(firstNumber.getText().toString());
}