Adding and computing values in android

Question

I'm a novice in the programming field and new help. In my xml file I have defined radio buttons that when selected a specific computation can be made but anytime it's checked, the app force closes. I also want to do a computation when a button is clicked, but when clicked, the app force closes. Please I need your expertise to be able to submit my assignment. Thanks in advance!!

Below is the MainActivity.java file

import android.os.Bundle;
import android.app.Activity;
import android.view.*;
import android.widget.*;

public class MainActivity extends Activity 
implements android.view.View.OnClickListener{



    Button compute;
        EditText inputRate, inputAmount, inputAns;
        RadioButton weekly, monthly, yearly;

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

            inputRate = (EditText)findViewById(R.id.inputRate);
            inputAmount = (EditText)findViewById(R.id.inputAmount);
            inputAns = (EditText)findViewById(R.id.inputAns);
            inputAns.setEnabled(false);
            compute = (Button)findViewById(R.id.buttoncompute);
            weekly = (RadioButton)findViewById(R.id.radioWeekly);
            monthly = (RadioButton)findViewById(R.id.radioMonthly);
            yearly = (RadioButton)findViewById(R.id.radioYearly);


            compute.setOnClickListener(this);
            weekly.setOnClickListener(this);
            monthly.setOnClickListener(this);
            yearly.setOnClickListener(this);

        }

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

        @Override
        public void onClick(View v) {
            Toast toast = Toast(compute);
            toast.show();

            double inputRateValue = -1; 
            try {inputRateValue = Double.parseDouble(inputRate.getText() .toString()); 
            // TODO Auto-generated method stub
            }
            catch (NumberFormatException e)
            {

            }
            double inputAmountValue = -1;
            try {
                inputAmountValue = Double.parseDouble(inputAmount.getText() .toString());
            }
        catch (NumberFormatException e)
        {

        }


            double inputAns = 0;

            inputAns = inputRateValue * inputAmountValue;

            inputAns += Double.parseDouble(compute.getText() .toString());
            compute.setText("" + inputAns);

        }

        private Toast Toast(Button compute2) {
            // TODO Auto-generated method stub
            return null;
        }

}

Below is my xml file

<TextView
    android:id="@+id/interestRate"
    android:layout_width="120dp"
    android:layout_height="wrap_content"
    android:textColor="#FFFFFF"
    android:textSize="22sp"
    android:text="@string/interest_rate"
     />

<EditText
    android:id="@+id/inputRate"
    android:layout_width="120dp"
    android:layout_height="wrap_content"
    android:layout_alignBottom="@+id/interestRate"
    android:layout_alignTop="@+id/interestRate"
    android:layout_toRightOf="@+id/interestRate"
    android:ems="10"
    android:inputType="number" />

<RadioButton
    android:id="@+id/radioWeekly"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignLeft="@+id/interestRate"
    android:layout_below="@+id/interestRate"
    android:textColor="#FFFFFF"
    android:layout_marginTop="19dp"
    android:text="@string/weekly" />

<RadioButton
    android:id="@+id/radioMonthly"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignLeft="@+id/radioWeekly"
    android:layout_below="@+id/radioWeekly"
    android:textColor="#FFFFFF"
    android:layout_marginTop="19dp"
    android:text="@string/monthly" />

<RadioButton
    android:id="@+id/radioYearly"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignLeft="@+id/radioMonthly"
    android:layout_below="@+id/radioMonthly"
    android:textColor="#FFFFFF"
    android:layout_marginTop="19dp"
    android:text="@string/yearly" />

<TextView 
    android:id="@+id/textAmount"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_below="@+id/radioYearly"
    android:textColor="#FFFFFF"
    android:layout_marginTop="19dp"
    android:textSize="22sp"
    android:text="@string/amount" />

<EditText
    android:id="@+id/inputAmount"
    android:layout_width="120dp"
    android:layout_height="wrap_content"
    android:layout_alignBaseline="@+id/textAmount"
    android:layout_alignBottom="@+id/textAmount"
    android:layout_toRightOf="@+id/interestRate"
    android:ems="10"
    android:inputType="number" />

<Button
    android:id="@+id/buttoncompute"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignLeft="@+id/textAmount"
    android:layout_alignRight="@+id/interestRate"
    android:layout_below="@+id/inputAmount"
    android:layout_marginTop="27dp"
    android:onClick=""
    android:text="@string/compute" />

<TextView 
    android:id="@+id/textResult"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_below="@+id/buttoncompute"
    android:layout_marginTop="22dp"
    android:textColor="#FFFFFF"
    android:textSize="22sp"
    android:text="@string/result" />

<EditText
    android:id="@+id/inputAns"
    android:layout_width="120dp"
    android:layout_height="wrap_content"
    android:layout_alignLeft="@+id/inputRate"
    android:layout_alignTop="@+id/textResult"
    android:ems="10"
    android:inputType="number" />

Answer 1

you need to surround the radio buttons with radio group like this xml file below :

<RadioGroup
android:id="@+id/radioGroup1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true"
android:layout_marginLeft="28dp"
android:layout_marginTop="34dp" >

<RadioButton
    android:id="@+id/radio0"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:checked="true"
    android:text="RadioButton" />

and defining the radio button in java like this :

Radiogroup group;
group.add(radiobutton1);

for yours Toast toast = Toast(compute);toast.show(); it should be like this:

String s ;
if(radiobutton1.isChecked){
   s = "weekly";
   Toast toast = Toast(this,s,Toast.LENGTH_SHORT);toast.show();}

where is s a String and inside it the sentence you want and this mean the context i think or the class and the last Toast.LENGTH_SHORT is the time of the toast. if it help accept if not post the log can thank you.

Answer 2

Toast toast = Toast(compute);

where compute is a Button does not make sense. Look for a tutorial on how to show a Toast, there's hundreds out there and it's easy. See this question / answer for example

For the future: you have to post your logcat output for people to see what the problem is.