'How to get textview input values to calculate when the user presses the button on my android application?

so this is my first application on Android Studio. I want the user to input 4 values: the first assignment mark, a second and a third with then the last value being the exam mark. There should be three calculations, one determining the yearmark which is calculated with this equation

Year Mark = Assigment1Mark * .15 + Assigment2Mark .35 + Assigment3Mark .50**

the second calculation should be for determining the final mark

Final Mark = yearMark .49 + examMark .5**

My Main Activity.java file

package com.example.mycalc;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

import androidx.appcompat.app.AppCompatActivity;

public class MainActivity extends AppCompatActivity {
    //onCreate Method
    @Override
    protected void onCreate(Bundle savedInstanceState){
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    //Initiating and referencing for Calculate Button
        Button button = (Button)findViewById(R.id.CalcButton);
    //onClickListener for the Calculate Button
        button.setOnClickListener(new View.OnClickListener(){
            public void onClick(View v){
                //TODO Auto generated method stub
                //Variables declared
                TextView ass1Mark = findViewById(R.id.assignment1);
                TextView ass2Mark = findViewById(R.id.assignment2);
                TextView ass3Mark = findViewById(R.id.assignment3);
                TextView examMark = findViewById(R.id.assignment4);
                TextView yearMark = findViewById(R.id.yearMark);
                TextView finalMark = findViewById(R.id.finalMark);
                //Calculations to execute when button is pressed
                yearMark.setText(ass1Mark * .15 + ass2Mark * .35 + ass3Mark * .50);
                finalMark.setText(yearMark*.49 + examMark*.5);
            }
        });
    }

}

My XML code

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout 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:id="@+id/layoutField"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@color/teal_700"
    android:importantForAccessibility="no"
    android:textAlignment="center"
    android:visibility="visible"
    tools:context=".MainActivity"
    tools:visibility="visible"
    >

    <EditText
        android:id="@+id/studentNum"
        android:layout_width="413dp"
        android:layout_height="50dp"
        android:autofillHints=""
        android:background="@color/black"
        android:hint="@string/studentNum"
        android:linksClickable="false"
        android:longClickable="false"
        android:text="@string/studentNum"
        android:textAlignment="center"
        android:textColor="#009688"
        android:textSize="20sp"
        android:textStyle="bold"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        tools:ignore="TouchTargetSizeCheck"
        android:inputType="text"
        />

    <EditText
        android:id="@+id/assignment1"
        android:layout_width="386dp"
        android:layout_height="wrap_content"
        android:layout_marginTop="32dp"
        android:digits="0 - 100"
        android:ems="10"
        android:hint="@string/ass1Mark"
        android:importantForAutofill="no"
        android:inputType="number"
        android:textColor="#000000"
        android:textColorHint="#000000"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.48"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/studentNum"
        tools:ignore="TouchTargetSizeCheck"
        tools:text="@string/ass1Mark" />

    <EditText
        android:id="@+id/assignment2"
        android:layout_width="386dp"
        android:layout_height="0dp"
        android:layout_marginTop="20dp"
        android:autofillHints=""
        android:digits="0 - 100"
        android:ems="10"
        android:hint="@string/ass2Mark"
        android:inputType="number"
        android:keepScreenOn="true"
        android:minHeight="50dp"
        android:singleLine="true"
        android:text="@string/ass2Mark"
        android:textColor="#000000"
        android:textColorHint="#000000"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.52"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/assignment1" />

    <EditText
        android:id="@+id/assignment3"
        android:layout_width="386dp"
        android:layout_height="wrap_content"
        android:layout_marginTop="20dp"
        android:autofillHints="example 50"
        android:digits="0 - 100"
        android:ems="10"
        android:hint="@string/ass3Mark"
        android:inputType="number"
        android:minHeight="50dp"
        android:text="@string/ass3Mark"
        android:textColor="#000000"
        android:textColorHint="#000000"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.48"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/assignment2" />

    <EditText
        android:id="@+id/assignment4"
        android:layout_width="386dp"
        android:layout_height="wrap_content"
        android:layout_marginTop="20dp"
        android:digits="0 - 100"
        android:ems="10"
        android:hint="@string/examMark"
        android:inputType="number"
        android:textColor="#000000"
        android:textColorHint="#000000"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.52"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/assignment3"
        tools:ignore="TouchTargetSizeCheck"
        tools:text="@string/examMark"
        android:autofillHints="" />

    <TextView
        android:id="@+id/errorMsg"
        android:layout_width="386dp"
        android:layout_height="50dp"
        android:layout_marginTop="20dp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.52"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/assignment4" />

    <Button
        android:id="@+id/CalcButton"
        android:layout_width="386dp"
        android:layout_height="50dp"
        android:layout_marginTop="20dp"
        android:background="@color/black"
        android:backgroundTint="#000000"
        android:backgroundTintMode="multiply"
        android:foregroundGravity="right"
        android:textAllCaps="true"
        app:icon="@color/black"
        app:iconTintMode="add"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.52"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/errorMsg"
        app:strokeColor="#009688"
        tools:text="@string/calculate" />

    <TextView
        android:id="@+id/finalMark"
        android:layout_width="236dp"
        android:layout_height="50dp"
        android:layout_marginStart="13dp"
        android:layout_marginTop="20dp"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/yearMark"
        tools:text="@string/finalMark" />

    <TextView
        android:id="@+id/status"
        android:layout_width="138dp"
        android:layout_height="50dp"
        android:layout_marginTop="20dp"
        android:layout_marginEnd="12dp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/yearMark"
        tools:text="@string/status" />

    <TextView
        android:id="@+id/yearMark"
        android:layout_width="386dp"
        android:layout_height="50dp"
        android:layout_marginTop="20dp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.52"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/CalcButton"
        tools:text="@string/yearMark" />


</androidx.constraintlayout.widget.ConstraintLayout>

The error that I get on my java file

Operator '*' cannot be applied to 'android.widget.TextView', 'double'

java android

Solution 1:^[1]

You can update your code as below. You have to take their value and parse them to a Double variable. and then you can calcualte and set those values to your desired TextViews.

public class MainActivity extends AppCompatActivity {
//onCreate Method
@Override
protected void onCreate(Bundle savedInstanceState){
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    //Initiating and referencing for Calculate Button
    Button button = (Button)findViewById(R.id.CalcButton);

    TextView ass1Mark = findViewById(R.id.assignment1);
    TextView ass2Mark = findViewById(R.id.assignment2);
    TextView ass3Mark = findViewById(R.id.assignment3);
    TextView examMark = findViewById(R.id.assignment4);
    TextView yearMark =  findViewById(R.id.yearMark);
    TextView finalMark = findViewById(R.id.finalMark);
    

    //onClickListener for the Calculate Button
    button.setOnClickListener(new View.OnClickListener(){
        public void onClick(View v){
            //TODO Auto generated method stub
            //Variables declared

            //Calculations to execute when button is pressed
            Double year_mark = Double.parseDouble(ass1Mark.getText().toString())*.15 +
                    Double.parseDouble(ass2Mark.getText().toString())*0.35+Double.parseDouble(ass3Mark.getText().toString())*0.50;
            Double final_mark = year_mark*0.49 + Double.parseDouble(examMark.getText().toString())*0.5;

            yearMark.setText(year_mark.toString());
            finalMark.setText(final_mark.toString());
        }
    });
}

}

Solution 2:^[2]

You're trying to multiply a TextView and a number (double) as mentioned in the error Operator '*' cannot be applied to 'android.widget.TextView', 'double'. How can it work?

What you've to do is first get the value from the TextView, parse it to int as it will be a String and then multiply it.

To get the value from a TextView, its getText() is used as

String text = ass2Mark.getText().toString();

Then, Parse it to integer/double as required:

//For Integer
int number = Integer.parseInt(text);
//For Double
double number = Double.parseDouble(text);

Then only, you can multiply it.

Solution 3:^[3]

You are trying to apply the * operator to an object of type TextView, at most the thing you could do is

double value = Double.parseDouble(editText.getText())

and then apply the operator *

Sources

This article follows the attribution requirements of Stack Overflow and is licensed under CC BY-SA 3.0.

Source: Stack Overflow

Solution	Source
Solution 1	Tuhin Mridha
Solution 2
Solution 3	afjcjsbx

'How to get textview input values to calculate when the user presses the button on my android application?

Solution 1:[1]

Solution 2:[2]

Solution 3:[3]

Sources

Related Questions

Solution 1:^[1]

Solution 2:^[2]

Solution 3:^[3]