Java图形用户界面

Question

I want to add two strings in java by getting data from two input fields. Result is shown in the 3rd field. I am using this code, but netbeans shows an error:

float num1,num2,result;
num1=Float.parseFloat(jTextField1.getText());
num2=Float.parseFloat(jTextField2.getText());
result=num1+num2;
jTextField3.setText(String.valueOf(result));

Answer 1

Thrown to indicate that the application has attempted to convert a string to one of the numeric types, but that the string does not have the appropriate format.

You will get a NumberFormatException if the text you entered isn't a proper number.Surround the parseFloat() statements in try-catch block. "Ahsan" isn't a number and hence cannot be parsed.

Make this little modification to your code:

try{
   num1=Float.parseFloat(jTextField1.getText());
   num2=Float.parseFloat(jTextField2.getText());
   result=num1+num2;
   jTextField3.setText(String.valueOf(result));
}catch(NumberFormatException e){
   e.printStackTrace();
}

Answer 2

If you get NumberFormatException it can happen in one of these 2 lines:

num1=Float.parseFloat(jTextField1.getText());
num2=Float.parseFloat(jTextField2.getText());

More specifically it is thrown from Float.parseFloat() . You pass unparsable value to this method. Check what jTextField1.getText() or jTextField2.getText() return. I believe that these fields are empty or contain text that cannot be interpreted as legal float .