如何解决数字格式异常

Question

I want to make app that solve Two variable two equation like;

aX+bY=c---(1)

dX+eY=F---(2)

And in My app i made six edit texts a,b,c,d,e,f. And other Text view to show X+,Y+,=. and then what values i fetch i set into Text view of valX and valY

My code is

package com.shubh.college_calculator;

import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import com.shubh.college_calculator.databinding.ActivityTwoVarBinding;

public class Two_var_act extends AppCompatActivity {
    ActivityTwoVarBinding binding;
    int A,B,C,D,E,F;
    String N,M;
    int X,Y;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        binding=ActivityTwoVarBinding.inflate(getLayoutInflater());
        setContentView(binding.getRoot());
        getSupportActionBar().hide();
        A=Integer.parseInt(binding.a.getText().toString());
         B=Integer.parseInt(binding.b.getText().toString());
        C=Integer.parseInt(binding.c.getText().toString());
        D=Integer.parseInt(binding.d.getText().toString());
        E=Integer.parseInt(binding.e.getText().toString());
        F=Integer.parseInt(binding.f.getText().toString());


        binding.calbtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {

                X= ((C*E)-(B*F))/((A*E)-(B*D));
                Y= ((C*D)-(A*F))/((B*D)-(A*E));
                N=Integer.toString(X);
                M=Integer.toString(Y);
                binding.valX.setText(N);
                binding.valY.setText(M);
            }
        });

    }
}

error is

 java.lang.RuntimeException: Unable to start activity ComponentInfo{com.shubh.college_calculator/com.shubh.college_calculator.Two_var_act}: java.lang.NumberFormatException: For input string: ""

Answer 1

The problem is Integer.parseInt(binding.a.getText().toString()) and all the subsequent statements eg: binding.b.getText().toString() is empty when the activity onCreate method is called. Integer.parseInt needs a valid number in a string to be able to parse it.

To fix this, check if the value is empty or not, maybe using binding.a.getText().toString().length() != 0 . If no, then go ahead and do the parsing.