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How to change Text view to int and use it in mathematical operations?

Hello I'm trying to make an app that gives you 2 random numbers and the user has to add the 2 random numbers, so my error is that that the random numbers are widgets not integers,
I have tried hundreds of explinations but nothing is working.
public void action(View v){
num1.setText(String.valueOf(randNum1.nextInt(10)));
num2.setText(String.valueOf(randNum2.nextInt(10)));
userAnswer.getText();
if (num1 + num2){
}
}
and this is the error:
bad operand types for binary operator '+' first type: TextView second
type: TextView

The problem you have is well described by the error you are receiving.
From the code snippet you have provided, I am guessing num1 and num2 are references to textview objects.
You CANNOT perform addition on the textview objects themselves, but rather on their content.
So, what you are trying to achieve is this:
public void action(View v){
num1.setText(String.valueOf(randNum1.nextInt(10)));
num2.setText(String.valueOf(randNum2.nextInt(10)));
userAnswer.getText();
String num1String = num1.getText().toString();
String num2String = num2.getText().toString();
int firstNumber = Integer.parseInt(num1String);
int secondNumber = Integer.parseInt(num2String);
if (firstNumber + secondNumber){
// YOUR LOGIC
}
}
Or better yet, you could save the generated random numbers to variables and use them later, like so:
public void action(View v){
int randomNumberOne = randNum1.nextInt(10);
int randomNumberTwo = randNum2.nextInt(10);
num1.setText(String.valueOf(randomNumberOne));
num2.setText(String.valueOf(randomNumberTwo));
userAnswer.getText();
if (randomNumberOne + randomNumberTwo){
// YOUR LOGIC
}
}

You can follow the below steps. i assume randNum1 and randNum2 is random number and num1 and num2 is TextView.
public void action(View v){
num1.setText(String.valueOf(randNum1.nextInt(10)));
num2.setText(String.valueOf(randNum2.nextInt(10)));
userAnswer.getText();
int randNumber1 = Integer.parseInt(num1.getText().toString());
int randNumber2 = Integer.parseInt(num2.getText().toString());
if (randNumber1 + randNumber2 ){
//your logic write here
}else{}
}

Returning nothing instead of NaN

I'm creating a simple app that calculates BMI and I'm struggling with one small problem. I have 2 edit text fields, which are allowed to type numbers only. The point is when one of the text fields are empty the app is to generate a toast message and display nothing. I wrote an if statement to check if an edit text is empty and if not just to calculate further.
All would work fine, but I needed to put return statement and Android Studio suggested me writing "return 0;" so did I.
This is the code responsible for calculations:
/// parse input value from edittext field into double type
private double weight() {
EditText weightInput = (EditText) findViewById(R.id.weight_input);
String sWeightInput = weightInput.getEditableText().toString();
if (sWeightInput.matches("")){
Toast.makeText(this, R.string.noweight, Toast.LENGTH_SHORT).show();
} else {
String weight = sWeightInput;
double weightTyped = Double.parseDouble(weight);
return weightTyped;
}
return 0;
}
private double heigh() {
EditText heightInput = (EditText) findViewById(R.id.height_input);
String sHightInput = heightInput.getEditableText().toString();
if (sHightInput.matches("")){
Toast.makeText(this, R.string.noheight, Toast.LENGTH_SHORT).show();
} else {
String height = sHightInput;
double heightTyped = Double.parseDouble(height);
heightTyped = heightTyped / 100;
heightTyped = heightTyped * heightTyped;
return heightTyped;
}
return 0;
}
//make calculations and return the output value
public void makeCalculations(View view){
double result = weight() / heigh();
String message = String.valueOf(result);
TextView bmiSummaryTextView = (TextView) findViewById(R.id.bmi_calculation);
bmiSummaryTextView.setText(message);
}
This is the interface of the app.
To sum up, all I want to do is to display nothing instead of NaN (not a number).

Return a non-primitive Double rather than a double, and you will be able to use null as a value. Be sure to check for this value though, or you'll run into a NullPointerException.
Alternatively, you could look into using optionals, but since you're using Android you might need an external library for that (unless your minimum SDK version is high enough, then you can use Java 8's Optional).

The problem is probably if in your calculation weight() / height height is 0 it outputs NaN because it is infinity.
Also put your return 0; after Toast.makeText() in the condition. AS grumbles because you are not returning a value in the if branch.
if (sHightInput.matches("")){
Toast.makeText(this, R.string.noheight, Toast.LENGTH_SHORT).show();
return 0;
}
Maybe this will help you also to avoid dividing by zero.
public void makeCalculations(View view) {
String message = "Invalid input!";
if (weight() > 0 && height() > 0) {
double result = weight() / heigh();
String message = String.valueOf(result);
}
TextView bmiSummaryTextView = (TextView) findViewById(R.id.bmi_calculation);
bmiSummaryTextView.setText(message);
}

EditText must have at least 10 characters? [duplicate]

This question already has an answer here:
EditText Minimum Length & Launch New Activity
(1 answer)
Closed 8 years ago.
I am a new developer on Android and Java. How can I make at least 10 characters in EditText ? Also, when the user enter a value less than 10, the application send an error message on screen. How can I do these ? [ edittext > = 10 ]

Use something like this:
EditText et = (EditText) findViewById(YOUR_EDITTEXT);
String s = et.getText().toString();
if(s.length() <= 10){
et.setError("Must exceed 10 characters!");
} else {
// ...
}

You can do that in several ways, but you can try this way:
if (myEditText.getText().length() < minLength) {
//Your message to there is no enough caracters
} else {
//Your action if it is satisfied.
}
You can set minLenght to 10, or whatever, or simply ask if value is less than 10.
I hope that you get idea from this.

You can use text watcher to check the user input and decide what to do inside
EditText editText = new EditText(this);
editText.addTextChangedListener(new TextWatcher() {
#Override
public void beforeTextChanged(CharSequence s, int start, int count, int after) {
}
#Override
public void onTextChanged(CharSequence s, int start, int before, int count) {
}
#Override
public void afterTextChanged(Editable s) {
}
});

Yo can validate your TextView and if it doesn't fit your requirements, use myTextView.setError(String) to show an error.
If not you will have to implement myTextView.addTextChangedListener(...) and do things manually.
Hope it helps.

Format Price in 0.00 format in android using edittext

I am trying to mask a price value so that it is always in 0.00 format. Here is my code
float temp = 0;
DecimalFormat mDecimalFormat = new DecimalFormat("###.00");
#Override
public void onTextChanged(CharSequence s, int start, int before, int count) {
if(s.toString()!=null)
{
mMasEditText.removeTextChangedListener(this);
temp = Float.parseFloat(s.toString());
mMasEditText.setText(""+mDecimalFormat.format(addNumber(temp)));
mMasEditText.setSelection(start+1);
mMasEditText.addTextChangedListener(this);
}
}
public float addNumber(float numTemp){
float result=0.00f;
result = numTemp + result;
return result;
}
But when I am pressing decimal, I want the cursor to go to one more step. But I am not able to get the dot callback. Also when I am pressing the back button, to remove digits, I get an index out of bound exception. Can anyone tell me how to get the back button and dot button callback before onTextChanged listener?

Recommended way of formatting currency and prices:
Locale loc = Locale.getDefault();
NumberFormat nf = NumberFormat.getCurrencyInstance(loc);
nf.setCurrency(Currency.getInstance(loc));
nf.setMaximumFractionDigits(2);
nf.setMinimumFractionDigits(2);
System.out.println(nf.format(23.5634));
System.out.println(nf.format(0.5));

use String.format
String.format("$%.2f", result);
or
Strint text = String.format("$%.2f", addNumber(temp));
mMasEditText.setText(text)

Filter Input in Real-Time?

I have an EditText (accepts 0-9) with a listener. I want to grab input as it's entered, apply a calculation, and display it in the same EditText box.
The box initially displays $0.00. When the user inputs a 2, I want to grab that from the box, parse it to remove the $ and decimal, convert it to an int... divide it by 100 and put a $ in front of it. After setText, it should display $0.02. If they then press 5, I'll grab it, parse it, end up with 25, do the math and it should display $0.25, etc.
I don't know if this is the best way, I'm open to new ideas. Here is my current code:
mEditPrice.addTextChangedListener(new TextWatcher(){
DecimalFormat dec = new DecimalFormat("0.00");
#Override
public void afterTextChanged(Editable arg0) {
}
#Override
public void beforeTextChanged(CharSequence s, int start,
int count, int after) {
}
#Override
public void onTextChanged(CharSequence s, int start,
int before, int count) {
String userInput = mEditPrice.getText().toString().replaceAll("[^\\d]", "");
int userInputInt = Integer.parseInt(userInput);
mEditPrice.setText("$"+dec.format(userInputInt / 100));
}

There's a few issues to deal with here before you can achieve the kind of functionality you desire.
Whenever you deal with a TextWatcher you need to be careful when setting the text of the EditText object being watched. The reason for this is that every time you call setText on it, it will trigger the watcher again, causing your code to go into an infinite loop.
To prevent this, you should set the value of text you want to set into a variable outside of the onTextChanged method. When entering the method, check against this variable and only perform your processing code if the value is different from the CharSequence.
The integer variable userInputInt, when divided by 100, will be equal to zero.
This should be changed to a double to produce values like 0.02 etc.
After those changes we can get the EditText to show $0.02 after entering a 2. But because we have set the value of the EditText in code, the next entry into the EditText will be added to the beginning of the text. Then if we enter a '5' we get $50.02.
To overcome this, the last thing we need to do is set the position of the EditText to the end of the string, using the set position method.
Here's the final solution:
private String value;
mEditPrice.addTextChangedListener(new TextWatcher(){
DecimalFormat dec = new DecimalFormat("0.00");
#Override
public void afterTextChanged(Editable arg0) {
}
#Override
public void beforeTextChanged(CharSequence s, int start, int count, int after) {
}
#Override
public void onTextChanged(CharSequence s, int start, int before, int count) {
if (!s.toString().equals(value)){
String userInput = mEditPrice.getText().toString().replaceAll("[^\\d]", "");
double userInputDouble = Double.parseDouble(userInput);
value = ("$"+dec.format(userInputDouble / 100));
mEditPrice.setText(value);
mEditPrice.setSelection(value.length());
}
}
});