CODEWITHSUNDEEP
androidandroid-studio
Tani
Tani

Reputation: 3

Getting App Stopped Error

Using Android Studio, can you point out the mistake please? I'm unable to analyze why I'm having to face this error: Have just basic background of java that's how I've created calculate method.

package com.tlians.t_calculator;

import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;


public class MainActivity extends ActionBarActivity {


Button add=(Button) findViewById(R.id.add);
Button sub=(Button) findViewById(R.id.sub);
Button times=(Button) findViewById(R.id.times);
Button div=(Button) findViewById(R.id.div);
EditText num1=(EditText) findViewById(R.id.num1);
EditText num2=(EditText) findViewById(R.id.num2);
TextView result=(TextView) findViewById(R.id.result);


public void calculate(char a){
    String N1=num1.getText().toString();
    String N2=num2.getText().toString();
    float n1=Float.parseFloat(N1);
    float n2=Float.parseFloat(N2);
    if(a=='+')
        result.setText(""+n1+n2);
    else if(a=='-')
        result.setText(""+(n1-n2));
    else if(a=='/')
        result.setText(""+n1/n2);
    else if(a=='*')
        result.setText(""+n1*n2);
    else
        result.setText("Tani has only assigned four functions right now.");

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

        add.setOnClickListener(new Button.OnClickListener(){
            public void onClick(View v){
                calculate('+');
            }
        });
        sub.setOnClickListener(new Button.OnClickListener(){
            public void onClick(View v){
                calculate('-');
            }

        });
        times.setOnClickListener(new Button.OnClickListener(){
            public void onClick(View v){
                calculate('*');
            }
        });
        div.setOnClickListener(new Button.OnClickListener(){
            public void onClick(View v){
                calculate('/');
            }
        });


}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.menu_main, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();

    //noinspection SimplifiableIfStatement
    if (id == R.id.action_settings) {
        return true;
    }

    return super.onOptionsItemSelected(item);
}
}

Upvotes: 0

Views: 40

Answers (2)

Pankaj
Pankaj

Reputation: 8058

Initialise all buttons and edittext inside onCreate() Method. You can declare buttons, edittext any component to global but dont initialise them as global. So do like this: 

Button add;
Button sub;
Button times;
Button div;
EditText num1;
EditText num2;
TextView result;

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

add=(Button) findViewById(R.id.add);
sub=(Button) findViewById(R.id.sub);
times=(Button) findViewById(R.id.times);
div=(Button) findViewById(R.id.div);
num1=(EditText) findViewById(R.id.num1);
num2=(EditText) findViewById(R.id.num2);
result=(TextView) findViewById(R.id.result);

.
.
.
//your button listener code

}

Upvotes: 0

rahul.ramanujam
rahul.ramanujam

Reputation: 5618

Button add;
Button sub;
Button times;
Button div;
EditText num1;
EditText num2;
TextView result;

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

Button add=(Button) findViewById(R.id.add);
 sub=(Button) findViewById(R.id.sub);
 times=(Button) findViewById(R.id.times);
 div=(Button) findViewById(R.id.div);
 num1=(EditText) findViewById(R.id.num1);
 num2=(EditText) findViewById(R.id.num2);
 result=(TextView) findViewById(R.id.result);

        add.setOnClickListener(new Button.OnClickListener(){
            public void onClick(View v){
                calculate('+');
            }
        });
        sub.setOnClickListener(new Button.OnClickListener(){
            public void onClick(View v){
                calculate('-');
            }

        });
        times.setOnClickListener(new Button.OnClickListener(){
            public void onClick(View v){
                calculate('*');
            }
        });
        div.setOnClickListener(new Button.OnClickListener(){
            public void onClick(View v){
                calculate('/');
            }
        });


}

Upvotes: 1

Related Questions