Programming backspace function in a java calculator.

I am doing a java calculator.
I want to program the backspace function, here is the code I have:
private void jbbackspaceMouseClicked(java.awt.event.MouseEvent evt) {
// TODO add your handling code here:
caja=Float.valueOf(jtfpantalla.getText()).floatValue();
if(caja==0){
jtfpantalla.setText("0");
else{
char caja2;
caja2=Float.toString(caja);
caja2.getChars(0,24,caja2,0);
jtfpantalla.setText(String.valueOf(caja));
Netbeans sends me 2 errors. I don't know how to use caja, as string or as an array. I want to convert it ,to print the characters of the array except the last character when the backspace button will be pressed.
I want to count the decimal point as another character, and print the characters except the last two when the decimal point is the penultime in the array.

I'd suggest that you store the temporary or displayed value in the calculator as a List of characters, or a String, and then don't ever turn it into a number until someone pushes the '=' button.
That's assuming I know what you're doing, which maybe I don't.

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Hi,
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