calculator

I have a calculator application in java swing, which is working properly with mouse click input. Now I want it to read input using keyboard button stroke. I had heard about the glass pane in java tutorial, but i need to know any other simple method to meet the requirement. KeyPadPanel is an example that uses Action and Key Bindings for numeric entry. 来源： https://stackoverflow.com/questions/10099686/calculator-application-including-keyboard-input-in-java-swing

I want to learn how calculators work. For example, say we have inputs in infix notation like this: 1 + 2 x 10 - 2 The parser would have to respect common rules in math. In the above example this means: 1 + (2 x 10) - 2 = 19 (rather than 3 x 10 - 2 = 28) And then consider this: 1 + 2 x ((2 / 9) + 7) - 2 Does it involve an Abstract Syntax Tree? A binary tree? How is the order of operations ensured to be mathematically correct? Must I use the shunting-yard algorithm to convert this to postfix notation? And then, how would I parse it in postfix notation? Why convert in the first place? Is there a

I am developing a demo for my app, in which there are two buttons named as "START" and "STOP". When user taps on "START" he will start walking. What I want to do is make it so that when users tap "STOP" then the demo will calculate his distance between "START" and "STOP". If the user pressed "START" and pressed "STOP" without taking a single step, then it must show 0km or 0m. I don't have any idea how I should start this; please make a suggestion. One way to go about it is using the accelerometer data. Your app should continuously record the accelerometer data after the user presses the Start

I am building a calculator and want it to automatically convert every decimal into a fraction. So if the user calculates an expression for which the answer is "0.333333...", it would return "1/3". For "0.25" it would return "1/4". Using GCD, as found here ( Decimal to fraction conversion ), I have figured out how to convert any rational, terminating decimal into a decimal, but this does not work on any decimal that repeats (like .333333). Every other function for this on stack overflow is in Objective-C. But I need a function in my swift app! So a translated version of this ( https:/

Let's say I have an equation: 2x + 6 = 12 With algebra we can see that x = 3 . How can I make a program in Python that can solve for x ? I'm new to programming, and I looked at eval() and exec() but I can't figure out how to make them do what I want. I do not want to use external libraries (e.g. SAGE), I want to do this in just plain Python. How about SymPy ? Their solver looks like what you need. Have a look at their source code if you want to build the library yourself… There are two ways to approach this problem: numerically and symbolically. To solve it numerically, you have to first