Why my app crashes when I parse string (from EditText) to Float-CodePudding

Why Am I not able to convert String (taken from EditText) to Float.

I was building a simple app to calculate (addition, subtraction, division, multiplication) of two numbers as per the radio group selection. But, As I extract string using

String temp =  editText.getText().toString();

and then try to convert it back into Float in order to perform operation on it

num1 = Float.parseFloat(temp);

This very line of code causes some error which crashes my app. I tried to surround it with try-catch which prevented crashing of my app but String was still not parsing into Float.

Complete Java Code for Calculator App

package com.example.calculator;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.util.Log;
import android.widget.EditText;
import android.widget.RadioGroup;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {
    RadioGroup radioGroup;
    float ans;
    EditText editText;
    TextView textView;
    float num1, num2;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        editText = findViewById(R.id.first_number);
        String temp =  editText.getText().toString();
        try{
            num1 = Float.parseFloat(temp);
        }catch(Exception e){
            Log.e("MainActivity", "onCreate: Still Not Working", e);
        }
        editText = findViewById(R.id.second_number);
        try{
            num2 = Float.parseFloat(editText.getText().toString());
        }catch(Exception e){
            Log.e("MainActivity", "onCreate: String unable to Assign.", e);
        }
        textView = findViewById(R.id.answer);
        radioGroup = (RadioGroup) findViewById(R.id.radio_group);
        radioGroup.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() {
            @Override
            public void onCheckedChanged(RadioGroup group, int checkedId) {

                caluclate(num1, num2);
                if(num2 == 0 && checkedId == R.id.div){
                    textView.setText("N.A.");
                }else{
                    textView.setText(String.valueOf(ans));
                }
            }
        });
    }


    float addition(float n1, float n2){
        return n1   n2;
    }
    float subtraction(float n1, float n2){
        return n1 - n2;
    }
    float multiplication(float n1, float n2){
        return n1 * n2;
    }
    float division(float n1, float n2){
        return n1/n2;
    }

    void caluclate(float n1, float n2){
        switch(radioGroup.getCheckedRadioButtonId()){
            case R.id.add:
                ans = addition (n1, n2);
                break;
            case R.id.sub:
                ans = subtraction(n1, n2);
                break;
            case R.id.mul:
                ans = multiplication(n1, n2);
                break;
            case R.id.div:
                ans = division(n1, n2);
                break;
        }
    }

}

XML Code

 <?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:background="#DFDFDF"
    android:orientation="vertical"
    tools:context=".MainActivity">

    <TextView

        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginLeft="16dp"
        android:layout_marginTop="16dp"
        android:layout_marginRight="16dp"
        android:text="First Number"
        android:textColor="#2196F3"
        android:textSize="20sp"
        android:textStyle="bold" />

    <EditText
        android:id="@ id/first_number"
        android:layout_width="match_parent"
        android:layout_height="48dp"
        android:layout_marginLeft="16dp"
        android:layout_marginTop="16dp"
        android:layout_marginRight="16dp"
        android:hint="Enter Here"
        android:inputType="numberDecimal|numberSigned"
        android:padding="8dp"
        android:background="@color/white"
        android:textStyle="bold" />

    <TextView

        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginLeft="16dp"
        android:layout_marginTop="16dp"
        android:layout_marginRight="16dp"
        android:text="Second Number"
        android:textColor="#2196F3"
        android:textSize="20sp"
        android:textStyle="bold" />

    <EditText
        android:id="@ id/second_number"
        android:layout_width="match_parent"
        android:layout_height="48dp"
        android:layout_marginLeft="16dp"
        android:layout_marginTop="16dp"
        android:layout_marginRight="16dp"
        android:hint="Enter Here"
        android:padding="8dp"
        android:inputType="numberDecimal|numberSigned"
        android:background="@color/white"
        android:textStyle="bold" />

    <TextView

        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginLeft="16dp"
        android:layout_marginTop="16dp"
        android:layout_marginRight="16dp"
        android:text="Choose Operation"
        android:textColor="#2196F3"
        android:textSize="20sp"
        android:textStyle="bold" />

    <RadioGroup
        android:id="@ id/radio_group"
        android:paddingLeft="16dp"
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

        <RadioButton
            android:id="@ id/add"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_marginRight="8dp"
            android:text="Addition" />

        <RadioButton
            android:id="@ id/sub"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_marginRight="8dp"
            android:text="Subtraction" />

        <RadioButton
            android:id="@ id/mul"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_marginRight="8dp"
            android:text="Multiplication" />

        <RadioButton
            android:id="@ id/div"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_marginRight="8dp"
            android:text="Division" />
    </RadioGroup>

    <TextView

        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginLeft="16dp"
        android:layout_marginTop="16dp"
        android:layout_marginRight="16dp"
        android:text="Answer"
        android:textColor="#2196F3"
        android:textSize="20sp"
        android:textStyle="bold" />

    <TextView
        android:id="@ id/answer"
        android:layout_width="match_parent"
        android:layout_height="48dp"
        android:layout_marginLeft="16dp"
        android:layout_marginTop="16dp"
        android:layout_marginRight="16dp"
        android:textSize="20dp"
        android:padding="8dp"
        android:inputType="number"
        android:background="@color/white"
        android:textStyle="bold" />

</LinearLayout>

My app was crashing until I comment out that line which assigns String to float then I tried using try-catch block but this just prevented my app from crashing

CodePudding user response：

here you go

you should get value from edittext at runtime when action perform,not at creating activity.

package com.example.calculator;

import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.widget.EditText;
import android.widget.RadioGroup;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {
    RadioGroup radioGroup;
    float ans;
    EditText editText1,editText2;
    TextView textView;
    float num1, num2;

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

        //make sure that you entered value contains float,not other data type

        editText1 = findViewById(R.id.first_number); 
        editText2 = findViewById(R.id.second_number);
        
        textView = findViewById(R.id.answer);
        radioGroup = (RadioGroup) findViewById(R.id.radio_group);
        radioGroup.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() {
            @Override
            public void onCheckedChanged(RadioGroup group, int checkedId) {
                try{
                    num1 = Float.parseFloat(editText1.getText().toString()); //i'm getting value here
                }catch(Exception e){
                    Log.e("MainActivity", "onCreate: Still Not Working", e);
                }
                try{
                    num2 = Float.parseFloat(editText2.getText().toString());//i'm getting value here
                }catch(Exception e){
                    Log.e("MainActivity", "onCreate: String unable to Assign.", e);
                }

                caluclate(num1, num2);
                if(num2 == 0 && checkedId == R.id.div){
                    textView.setText("N.A.");
                }else{
                    textView.setText(String.valueOf(ans));
                }
            }
        });
    }


    float addition(float n1, float n2){
        return n1   n2;
    }
    float subtraction(float n1, float n2){
        return n1 - n2;
    }
    float multiplication(float n1, float n2){
        return n1 * n2;
    }
    float division(float n1, float n2){
        return n1/n2;
    }

    void caluclate(float n1, float n2){
        switch(radioGroup.getCheckedRadioButtonId()){
            case R.id.add:
                ans = addition (n1, n2);
                break;
            case R.id.sub:
                ans = subtraction(n1, n2);
                break;
            case R.id.mul:
                ans = multiplication(n1, n2);
                break;
            case R.id.div:
                ans = division(n1, n2);
                break;
        }
    }

}