Substring removes 2 characters instead of 1
up vote
1
down vote
favorite
My assignment requires me to have this clear last button which removes the last character in a string. as seen from the code, it SHOULD exclude that last number.
Problem is that when I press it the first time after inputting numbers, it removes 2 and subsequent uses take out 1. any idea how to fix this?
code:
case "Clear Last":
String remove;
remove = text.substring(text.length()-1);
switch (remove) {
case "+":
add = false;
text = text.substring(0, text.length() - 1);
display.setText(text);
break;
case "-":
subtract = false;
text = text.substring(0, text.length() - 1);
display.setText(text);
break;
case "*":
multiply = false;
text = text.substring(0, text.length() - 1);
display.setText(text);
break;
case "/":
divide = false;
text = text.substring(0, text.length() - 1);
display.setText(text);
break;
default:
text = text.substring(0, text.length()-1);
display.setText(text);
break;
}
break;
Example output:
77777 -> Clear Last -> 777 -> Clear Last -> 77 -> 778888 -> Clear Last -> 7788 -> Clear Last -> 778
java string switch-statement substring
asked Nov 20 at 0:33
John
83
|
show 3 more comments
up vote
1
down vote
favorite
My assignment requires me to have this clear last button which removes the last character in a string. as seen from the code, it SHOULD exclude that last number.
Problem is that when I press it the first time after inputting numbers, it removes 2 and subsequent uses take out 1. any idea how to fix this?
code:
case "Clear Last":
String remove;
remove = text.substring(text.length()-1);
switch (remove) {
case "+":
add = false;
text = text.substring(0, text.length() - 1);
display.setText(text);
break;
case "-":
subtract = false;
text = text.substring(0, text.length() - 1);
display.setText(text);
break;
case "*":
multiply = false;
text = text.substring(0, text.length() - 1);
display.setText(text);
break;
case "/":
divide = false;
text = text.substring(0, text.length() - 1);
display.setText(text);
break;
default:
text = text.substring(0, text.length()-1);
display.setText(text);
break;
}
break;
Example output:
77777 -> Clear Last -> 777 -> Clear Last -> 77 -> 778888 -> Clear Last -> 7788 -> Clear Last -> 778
java string switch-statement substring
asked Nov 20 at 0:33
John
83
1
Please provide a Minimal, Complete, and Verifiable example.
– shmosel
Nov 20 at 0:37
it's a java GUI Calculator so it might be a little big. I'll add it in the OP then @shmosel
– John
Nov 20 at 0:44
If it's big, cut it down to just the code necessary to reproduce the problem. You might even discover the problem yourself in the process.
– shmosel
Nov 20 at 0:44
@shmosel done. still pretty big tho. removed it from the package so it should run a bit easier
– John
Nov 20 at 1:00
Why do you have so much duplicated code?
– shmosel
Nov 20 at 1:13
|
show 3 more comments
up vote
1
down vote
favorite
up vote
1
down vote
favorite
My assignment requires me to have this clear last button which removes the last character in a string. as seen from the code, it SHOULD exclude that last number.
Problem is that when I press it the first time after inputting numbers, it removes 2 and subsequent uses take out 1. any idea how to fix this?
code:
case "Clear Last":
String remove;
remove = text.substring(text.length()-1);
switch (remove) {
case "+":
add = false;
text = text.substring(0, text.length() - 1);
display.setText(text);
break;
case "-":
subtract = false;
text = text.substring(0, text.length() - 1);
display.setText(text);
break;
case "*":
multiply = false;
text = text.substring(0, text.length() - 1);
display.setText(text);
break;
case "/":
divide = false;
text = text.substring(0, text.length() - 1);
display.setText(text);
break;
default:
text = text.substring(0, text.length()-1);
display.setText(text);
break;
}
break;
Example output:
77777 -> Clear Last -> 777 -> Clear Last -> 77 -> 778888 -> Clear Last -> 7788 -> Clear Last -> 778
java string switch-statement substring
asked Nov 20 at 0:33
John
83
My assignment requires me to have this clear last button which removes the last character in a string. as seen from the code, it SHOULD exclude that last number.
Problem is that when I press it the first time after inputting numbers, it removes 2 and subsequent uses take out 1. any idea how to fix this?
code:
case "Clear Last":
String remove;
remove = text.substring(text.length()-1);
switch (remove) {
case "+":
add = false;
text = text.substring(0, text.length() - 1);
display.setText(text);
break;
case "-":
subtract = false;
text = text.substring(0, text.length() - 1);
display.setText(text);
break;
case "*":
multiply = false;
text = text.substring(0, text.length() - 1);
display.setText(text);
break;
case "/":
divide = false;
text = text.substring(0, text.length() - 1);
display.setText(text);
break;
default:
text = text.substring(0, text.length()-1);
display.setText(text);
break;
}
break;
Example output:
77777 -> Clear Last -> 777 -> Clear Last -> 77 -> 778888 -> Clear Last -> 7788 -> Clear Last -> 778
java string switch-statement substring
java string switch-statement substring
asked Nov 20 at 0:33
John
83
asked Nov 20 at 0:33
John
83
edited Nov 21 at 6:41
asked Nov 20 at 0:33
John
83
asked Nov 20 at 0:33
John
83
asked Nov 20 at 0:33
John
83
83
1
Please provide a Minimal, Complete, and Verifiable example.
– shmosel
Nov 20 at 0:37
it's a java GUI Calculator so it might be a little big. I'll add it in the OP then @shmosel
– John
Nov 20 at 0:44
If it's big, cut it down to just the code necessary to reproduce the problem. You might even discover the problem yourself in the process.
– shmosel
Nov 20 at 0:44
@shmosel done. still pretty big tho. removed it from the package so it should run a bit easier
– John
Nov 20 at 1:00
Why do you have so much duplicated code?
– shmosel
Nov 20 at 1:13
|
show 3 more comments
1
Please provide a Minimal, Complete, and Verifiable example.
– shmosel
Nov 20 at 0:37
it's a java GUI Calculator so it might be a little big. I'll add it in the OP then @shmosel
– John
Nov 20 at 0:44
If it's big, cut it down to just the code necessary to reproduce the problem. You might even discover the problem yourself in the process.
– shmosel
Nov 20 at 0:44
@shmosel done. still pretty big tho. removed it from the package so it should run a bit easier
– John
Nov 20 at 1:00
Why do you have so much duplicated code?
– shmosel
Nov 20 at 1:13
1
1
Please provide a Minimal, Complete, and Verifiable example.
– shmosel
Nov 20 at 0:37
Please provide a Minimal, Complete, and Verifiable example.
– shmosel
Nov 20 at 0:37
it's a java GUI Calculator so it might be a little big. I'll add it in the OP then @shmosel
– John
Nov 20 at 0:44
it's a java GUI Calculator so it might be a little big. I'll add it in the OP then @shmosel
– John
Nov 20 at 0:44
If it's big, cut it down to just the code necessary to reproduce the problem. You might even discover the problem yourself in the process.
– shmosel
Nov 20 at 0:44
If it's big, cut it down to just the code necessary to reproduce the problem. You might even discover the problem yourself in the process.
– shmosel
Nov 20 at 0:44
@shmosel done. still pretty big tho. removed it from the package so it should run a bit easier
– John
Nov 20 at 1:00
@shmosel done. still pretty big tho. removed it from the package so it should run a bit easier
– John
Nov 20 at 1:00
Why do you have so much duplicated code?
– shmosel
Nov 20 at 1:13
Why do you have so much duplicated code?
– shmosel
Nov 20 at 1:13
|
show 3 more comments
1 Answer
1
active
oldest
votes
up vote
1
down vote
accepted
The problem is here (and all such snippets):-
text = display.getText();
display.setText(text + "7");
You are updating the text before you update the display. You should interchange them and it should work:-
display.setText(text + "7");
text = display.getText();
Even better, just update the value of text and set display outside switch, something like this:-
public void actionPerformed(ActionEvent e) {
switch (e.getActionCommand()) {
case "1":
case "2":
case "3":
case "4":
case "5":
case "6":
case "7":
case "8":
case "9":
case "0":
case ".":
text += e.getActionCommand();
break;
case "=":
break;
case "Clear Last":
text = text.substring(0, (text.length() - 1));
break;
case "Clear All":
text = "";
break;
default:
text = "";
break;
}
display.setText(text);
}
Or improve it even further by getting rid of the switch-case - check if e.getActionCommand() is a digit, then do text += e.getActionCommand();, else if....
answered Nov 20 at 1:35
Kartik
2,48931331
Wow. Didn't know that was possible reducing the code down hard like that. It's beautiful. I'll try this out right now.
– John
Nov 20 at 1:43
Hot damn. This worked! Thank you so much! That text += e.getActionCommand(); worked perfectly! Now I'll have to set another switch statement so it does nothing if text is null or it's length is 0 or less.
– John
Nov 20 at 1:57
yourdefaultcase should handle it.. if you want to do it manually, you can writeif (e.getActionCommand() != null && !e.getActionCommand().isEmpty())just before theswitch.. Java is beautiful, isn't it?
– Kartik
Nov 20 at 1:59
add a comment |
1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
up vote
1
down vote
accepted
The problem is here (and all such snippets):-
text = display.getText();
display.setText(text + "7");
You are updating the text before you update the display. You should interchange them and it should work:-
display.setText(text + "7");
text = display.getText();
Even better, just update the value of text and set display outside switch, something like this:-
public void actionPerformed(ActionEvent e) {
switch (e.getActionCommand()) {
case "1":
case "2":
case "3":
case "4":
case "5":
case "6":
case "7":
case "8":
case "9":
case "0":
case ".":
text += e.getActionCommand();
break;
case "=":
break;
case "Clear Last":
text = text.substring(0, (text.length() - 1));
break;
case "Clear All":
text = "";
break;
default:
text = "";
break;
}
display.setText(text);
}
Or improve it even further by getting rid of the switch-case - check if e.getActionCommand() is a digit, then do text += e.getActionCommand();, else if....
answered Nov 20 at 1:35
Kartik
2,48931331
Wow. Didn't know that was possible reducing the code down hard like that. It's beautiful. I'll try this out right now.
– John
Nov 20 at 1:43
Hot damn. This worked! Thank you so much! That text += e.getActionCommand(); worked perfectly! Now I'll have to set another switch statement so it does nothing if text is null or it's length is 0 or less.
– John
Nov 20 at 1:57
yourdefaultcase should handle it.. if you want to do it manually, you can writeif (e.getActionCommand() != null && !e.getActionCommand().isEmpty())just before theswitch.. Java is beautiful, isn't it?
– Kartik
Nov 20 at 1:59
add a comment |
up vote
1
down vote
accepted
The problem is here (and all such snippets):-
text = display.getText();
display.setText(text + "7");
You are updating the text before you update the display. You should interchange them and it should work:-
display.setText(text + "7");
text = display.getText();
Even better, just update the value of text and set display outside switch, something like this:-
public void actionPerformed(ActionEvent e) {
switch (e.getActionCommand()) {
case "1":
case "2":
case "3":
case "4":
case "5":
case "6":
case "7":
case "8":
case "9":
case "0":
case ".":
text += e.getActionCommand();
break;
case "=":
break;
case "Clear Last":
text = text.substring(0, (text.length() - 1));
break;
case "Clear All":
text = "";
break;
default:
text = "";
break;
}
display.setText(text);
}
Or improve it even further by getting rid of the switch-case - check if e.getActionCommand() is a digit, then do text += e.getActionCommand();, else if....
answered Nov 20 at 1:35
Kartik
2,48931331
Wow. Didn't know that was possible reducing the code down hard like that. It's beautiful. I'll try this out right now.
– John
Nov 20 at 1:43
Hot damn. This worked! Thank you so much! That text += e.getActionCommand(); worked perfectly! Now I'll have to set another switch statement so it does nothing if text is null or it's length is 0 or less.
– John
Nov 20 at 1:57
yourdefaultcase should handle it.. if you want to do it manually, you can writeif (e.getActionCommand() != null && !e.getActionCommand().isEmpty())just before theswitch.. Java is beautiful, isn't it?
– Kartik
Nov 20 at 1:59
add a comment |
up vote
1
down vote
accepted
up vote
1
down vote
accepted
The problem is here (and all such snippets):-
text = display.getText();
display.setText(text + "7");
You are updating the text before you update the display. You should interchange them and it should work:-
display.setText(text + "7");
text = display.getText();
Even better, just update the value of text and set display outside switch, something like this:-
public void actionPerformed(ActionEvent e) {
switch (e.getActionCommand()) {
case "1":
case "2":
case "3":
case "4":
case "5":
case "6":
case "7":
case "8":
case "9":
case "0":
case ".":
text += e.getActionCommand();
break;
case "=":
break;
case "Clear Last":
text = text.substring(0, (text.length() - 1));
break;
case "Clear All":
text = "";
break;
default:
text = "";
break;
}
display.setText(text);
}
Or improve it even further by getting rid of the switch-case - check if e.getActionCommand() is a digit, then do text += e.getActionCommand();, else if....
answered Nov 20 at 1:35
Kartik
2,48931331
The problem is here (and all such snippets):-
text = display.getText();
display.setText(text + "7");
You are updating the text before you update the display. You should interchange them and it should work:-
display.setText(text + "7");
text = display.getText();
Even better, just update the value of text and set display outside switch, something like this:-
public void actionPerformed(ActionEvent e) {
switch (e.getActionCommand()) {
case "1":
case "2":
case "3":
case "4":
case "5":
case "6":
case "7":
case "8":
case "9":
case "0":
case ".":
text += e.getActionCommand();
break;
case "=":
break;
case "Clear Last":
text = text.substring(0, (text.length() - 1));
break;
case "Clear All":
text = "";
break;
default:
text = "";
break;
}
display.setText(text);
}
Or improve it even further by getting rid of the switch-case - check if e.getActionCommand() is a digit, then do text += e.getActionCommand();, else if....
answered Nov 20 at 1:35
Kartik
2,48931331
edited Nov 20 at 1:45
answered Nov 20 at 1:35
Kartik
2,48931331
answered Nov 20 at 1:35
Kartik
2,48931331
answered Nov 20 at 1:35
Kartik
2,48931331
2,48931331
Wow. Didn't know that was possible reducing the code down hard like that. It's beautiful. I'll try this out right now.
– John
Nov 20 at 1:43
Hot damn. This worked! Thank you so much! That text += e.getActionCommand(); worked perfectly! Now I'll have to set another switch statement so it does nothing if text is null or it's length is 0 or less.
– John
Nov 20 at 1:57
yourdefaultcase should handle it.. if you want to do it manually, you can writeif (e.getActionCommand() != null && !e.getActionCommand().isEmpty())just before theswitch.. Java is beautiful, isn't it?
– Kartik
Nov 20 at 1:59
add a comment |
Wow. Didn't know that was possible reducing the code down hard like that. It's beautiful. I'll try this out right now.
– John
Nov 20 at 1:43
Hot damn. This worked! Thank you so much! That text += e.getActionCommand(); worked perfectly! Now I'll have to set another switch statement so it does nothing if text is null or it's length is 0 or less.
– John
Nov 20 at 1:57
yourdefaultcase should handle it.. if you want to do it manually, you can writeif (e.getActionCommand() != null && !e.getActionCommand().isEmpty())just before theswitch.. Java is beautiful, isn't it?
– Kartik
Nov 20 at 1:59
Wow. Didn't know that was possible reducing the code down hard like that. It's beautiful. I'll try this out right now.
– John
Nov 20 at 1:43
Wow. Didn't know that was possible reducing the code down hard like that. It's beautiful. I'll try this out right now.
– John
Nov 20 at 1:43
Hot damn. This worked! Thank you so much! That text += e.getActionCommand(); worked perfectly! Now I'll have to set another switch statement so it does nothing if text is null or it's length is 0 or less.
– John
Nov 20 at 1:57
Hot damn. This worked! Thank you so much! That text += e.getActionCommand(); worked perfectly! Now I'll have to set another switch statement so it does nothing if text is null or it's length is 0 or less.
– John
Nov 20 at 1:57
your
default case should handle it.. if you want to do it manually, you can write if (e.getActionCommand() != null && !e.getActionCommand().isEmpty()) just before the switch.. Java is beautiful, isn't it?– Kartik
Nov 20 at 1:59
your
default case should handle it.. if you want to do it manually, you can write if (e.getActionCommand() != null && !e.getActionCommand().isEmpty()) just before the switch.. Java is beautiful, isn't it?– Kartik
Nov 20 at 1:59
add a comment |
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1
Please provide a Minimal, Complete, and Verifiable example.
– shmosel
Nov 20 at 0:37
it's a java GUI Calculator so it might be a little big. I'll add it in the OP then @shmosel
– John
Nov 20 at 0:44
If it's big, cut it down to just the code necessary to reproduce the problem. You might even discover the problem yourself in the process.
– shmosel
Nov 20 at 0:44
@shmosel done. still pretty big tho. removed it from the package so it should run a bit easier
– John
Nov 20 at 1:00
Why do you have so much duplicated code?
– shmosel
Nov 20 at 1:13