Develop Reference

Android app crashes when no value is in edit text

I am making a unit converter, but if I do not enter any value into edit text and press the calculate button the app crashes with error Invalid float: "". Also, I want to forbid zeroes from being entered before numbers (eg. 0300). How do I accomplish this?
//handle calculate
calcButton=(Button)findViewById(R.id.calcButton);
calcButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Spinner spinner = (Spinner) findViewById(R.id.unit_spinner);
String spinnerText = spinner.getSelectedItem().toString();
EditText unit_edit = (EditText) findViewById(R.id.unit_edit);
amount = Float.valueOf(unit_edit.getText().toString());
if (unit_edit.getText().toString().equals(null)) {
Toast.makeText(getApplicationContext(), "Insert Value To Convert",
Toast.LENGTH_LONG).show();
} else {
switch (spinnerText) {
case "Kilograms":
kilograms = amount;
grams = amount * 1000;
ListView();
break;
case "Grams":
grams = amount;
kilograms = amount / 1000;
ListView();
break;
}
}
}
});
}

You are probably getting an NumberFormatException thrown since the EditText fields text is "" and "" is not a valid float value, the exception is thrown at the following line:
amount = Float.valueOf(unit_edit.getText().toString());
What you'll need to do is add some validation and checking before trying to get the float value of a String.
Check the methods documentation for more details http://docs.oracle.com/javase/7/docs/api/java/lang/Double.html#valueOf(java.lang.String)

This might be useful for your EditText to limit input to numbers only.
<EditText
android:id="#+id/unit_edit"
android:inputType="number"
/>
You can also limit the digits, type of number such as decimal
<EditText
android:id="#+id/unit_edit"
android:digits="0123456789."
android:inputType="numberDecimal"
/>

You can't parse an empty value to float. You should first test if it's empty, and then do what you want, something like this:
String text = unit_edit.getText().toString();
if(!text.isEmpty()){ // Test if the text is empty
if(text.matches("[0-9]+")){ // Test if it only contains numbers, using REGEX
amount = Float.valueOf(text); // Only then parse to float.
// Switch and rest of the stuff
} else {
Toast.makeText(getApplicationContext(), "Use only numbers from 0 to 9.",
Toast.LENGTH_LONG).show();
}
} else {
Toast.makeText(getApplicationContext(), "The field is empty",
Toast.LENGTH_LONG).show();
}
The comments explain what's going on. About the leading 0 in some numbers, using "valueOf" will remove it already, and 0300 will be parsed as 300, so there's nothing to worry about.If you still want something related to it, let me know and i'll edit my answer.

if /else statement not working in android app

I am writing an app that takes two user inputs and matches them to data stored in a database and displays the corresponding data(row) from the user inputs in a textview.
The if statement works perfectly alone if d condition is true. It however stops working if I add the else statement.
The else statement is executed if d statement is true or false
String name = Jasonobject.getString("name");
String name1 = Jasonobject.getString("name1");
String db_detail = "";
// match user input with database and display corresponding row in
// "detail" textfield
if (et.getText().toString().equalsIgnoreCase(name)
&& et1.getText().toString().equalsIgnoreCase(name1)) {
db_detail = Jasonobject.getString("detail");
text.setText(db_detail);
break;
} else {
Context context = getApplicationContext();
CharSequence text = "NOT AVAILABLE";
int duration = Toast.LENGTH_LONG;
Toast toast = Toast.makeText(context, text, duration);
toast.show();
break;
}

The else statement cannot run if the if statement is true at any cost.
Try to clean your project and re-compile it. Also are you executing this code in an loop, if not then you should get a misplace break error.

Comparing two EditText values in android

I'm trying to make an app where the user enters a word into an EditText box. Then, they enter something into another box and it checks to see if they are the same word. Here's the code that I used:
String word = textfield1.getText().toString();
String answer = textfield2.getText().toString();
textfield2.setText(textfield2.getText().toString());
if(word == answer){
Toast.makeText(getApplicationContext(), "correct",
Toast.LENGTH_LONG).show();
}else
Toast.makeText(getApplicationContext(), "incorrect", Toast.LENGTH_LONG).show();
}
However, it always says that the two strings aren't the same even if they are. Is there a way to fix this?

You can't compare strings with the == operator.
Use .equals() instead:
if(word.equals(answer)) {
//do whatever
}

Use String.equalsIgnoreCase for comparing content of both string variables.:
if(word.equalsIgnoreCase(answer)){
}

Use:
String word = textfield1.getText().toString();
String answer = textfield2.getText().toString();
if(answer.contentEquals(word)){
// Do something if equals
}
else{
// Do something if not equals
}

I think the best way to do this is using TextUtils:
if(TextUtils.equals(textfield1.getText(),textfield2.getText())){
//do something
}

instead of
if(word.contentEquals(answer)){
}
Use
if(word.equals(answer))
as we cant compare strings with Equal to (==) operator
Try This::
String word = textfield1.getText().toString();
String answer = textfield2.getText().toString();
if(word.equals(answer)){
Toast.makeText(getApplicationContext(), "correct",
Toast.LENGTH_LONG).show();
}else
Toast.makeText(getApplicationContext(), "incorrect", Toast.LENGTH_LONG).show();
}

editText box not working properly. Android

I'm trying to get values out of edittext boxes and on the click of a button, I want to compare if the text inside the edittext box matches a certain value. If it does, a new intent should be called. If it doesn't it should show an error. Here is my code after the button is clicked...
if(v.getId() == R.id.button1){
id = et1.getText().toString();
Toast toast = Toast.makeText(this, "Value of id is: " + id, Toast.LENGTH_SHORT);
toast.show();
if(id == "abc"){
Intent i= new Intent(Slogin.this, Sales.class);
startActivity(i);
}else{
Toast toast = Toast.makeText(this, "Wrong id pass", Toast.LENGTH_SHORT);
toast.show();
}
Now the problem is that even when I enter "abc" (without the double commas), it still shows me the error "Wrong id pass". While the Toast clearly shows that I have entered abd and the string id now holds the value "abc". Help required...

Try this.. if id is int use like this id == 5. but id is String you should use id.equals("abc")
if(id.equals("abc")){ //Correction is here
Intent i= new Intent(Slogin.this, Sales.class);
startActivity(i);
}else{
Toast toast = Toast.makeText(this, "Wrong id pass", Toast.LENGTH_SHORT);
toast.show();
}
== always just compares two references (for non-primitives, that is) - i.e. it tests whether the two operands refer to the same object.
However, the equals method can be overridden - so two distinct objects can still be equal......

Use
if(id.equals("abc"))
instead Of
if(id == "abc")

validating EditText input

Trying to confirm that an EditText tool is not empty when the user clicks a button. Whenever the EditText is not blank the code works. But whenever it is blank my program crashes. Any ideas what I'm doing wrong? Thanks.
if (et1.getText().toString() != null) {
inpt_weight = Integer.parseInt(et1.getText().toString());
Toast.makeText(getBaseContext(), "weight is not null", Toast.LENGTH_LONG).show();
} else {
inpt_weight = 0;
Toast.makeText(getBaseContext(), "weight is null", Toast.LENGTH_LONG).show();
};

I think its trying to parse an empty string("") to an integer which is not possible
try:
if (!et1.getText().toString().equalsIgnoreCase("") && et1.getText().toString() != null)

This will be a good way:
if(et1.getText().toString().trim().length()==0){
Log.d("No data","No text found in the edit text");
}
This also checks if the user had put nothing but only spaces.
In your code, I see you're converting the text to numbers.
In this case, either put correct IMEMethod for the edit text so that it takes only numbers, or check in your code that user has entered only numeric characters, else you'll end up with a NumberFormatException while conversion if the user has entered non numeric characters.

Try the following code please..
if(et1.getText().toString().equals("")){
Toast.makeText(getApplication(), "weight is null", Toast.LENGTH_SHORT).show();}
else{
inpt_weight = Integer.parseInt(et1.getText().toString());
Toast.makeText(getApplication(), "weight is not null & it is : "+inpt_weight,Toast.LENGTH_SHORT).show();
}