如何向此计算器程序添加可分割函数?

Question

所以下面我有一个计算器功能。我的加法、减法和乘法工作得很好。实际计算不是这里的问题。(注意：计算一起在不同的类中(。我只需要弄清楚如何在启动计算器 gui 时使"/"符号显示在计算器 gui 上。

import javafx.application.Application;
import javafx.beans.binding.Bindings;
import javafx.beans.property.DoubleProperty;
import javafx.beans.property.SimpleDoubleProperty;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.TextField;
import javafx.scene.layout.TilePane;
import javafx.scene.layout.VBox;
import javafx.scene.text.Font;
import javafx.stage.Stage;
import javafx.stage.StageStyle;

/* This is the GUI class that visualize the calculator 
* 
* */
public class Calculator extends Application {
private MyStack stack = new MyStack();
private double font_size = 30; //by default the font size on the screen is 30
/*The keyboard key values*/
private static final String[][] key_values = {
{ "0", "=", "c", "<" },
{ "1", "2", "3", "-" },
{ "4", "5", "6", "*" },
{ "7", "8", "9", "+" },
{ "/"}
};
private Button btn[][] = new Button[5][5]; //all the key buttons
TextField calculator_screen;  //the calculator screen

public static void main(String[] args) { launch(args); }
@Override public void start(Stage stage) {
/*The outside layout*/
final VBox layout = new VBox(30); //the size vertically
/*The inside layout for keys or buttons*/
TilePane keypad = new TilePane(); //even it is called keypad, it is a layout
keypad.setVgap(7);
keypad.setHgap(7); //set the gap between keys

/*Create Calculator Screen */
calculator_screen =  new TextField();
calculator_screen.getStyleClass().add("screen1"); //set the style of the screen
calculator_screen.setAlignment(Pos.CENTER_RIGHT); //make the screen in the center of the calculator
calculator_screen.setEditable(false); //make sure the screen cannot be typed in manually
calculator_screen.setPrefWidth(300); //set the width of the screen
calculator_screen.setPrefHeight(30);
calculator_screen.setFont(Font.font("Verdana", font_size));
/*Create Calculator keyboard*/
keypad.setPrefColumns(key_values[0].length); //set the preferred number of columns
for (int i = 0; i < 4; i++) {
for (int j = 0; j < 4; j++) {
btn[i][j] = new Button(key_values[i][j]);
final int a = i;
final int b = j;
/*Add button event*/
btn[i][j].setOnAction(new EventHandler<ActionEvent>(){
@Override
public void handle(ActionEvent event) {
StackNode node = new StackNode(key_values[a][b]);

if(a == 0 && b == 2) //if the key is "c"
{
stack.clear();
calculator_screen.setFont(Font.font("Verdana", 30));
font_size = 30;
}
else if(a == 0 && b == 3) //if the key is "b"
stack.pop();
else if (a == 0 && b == 1) // if the key is "="
{
stack.computeExp();
}
else
stack.push(node); //otherwise push the key into the list
String math_exp = stack.getAllNodeValues();
if(math_exp.length() * font_size > 1.2 * calculator_screen.getPrefWidth())
{
font_size /= 1.2;
calculator_screen.setFont(Font.font("Verdana", font_size));
}
calculator_screen.setText(math_exp);
}
}
);  
//Add special style for the "=" button
if(a == 0 && b == 1)
btn[i][j].getStyleClass().add("btnEqual");
else if(a == 0 && b == 2)
btn[i][j].getStyleClass().add("btnClear");
else if(a == 0 && b == 3)
btn[i][j].getStyleClass().add("btnBackspace");
keypad.getChildren().add(btn[i][j]);
}
}
/*Put the calculator screen and keypad into a VBox layout*/
layout.setAlignment(Pos.CENTER);
layout.getChildren().addAll(calculator_screen, keypad);
layout.getStyleClass().add("vbox1");
calculator_screen.prefWidthProperty().bind(keypad.widthProperty());

/*Show the window*/
stage.setTitle("Calculator");
stage.initStyle(StageStyle.UTILITY);
stage.setResizable(false);
Scene scene = new Scene(layout);
scene.getStylesheets().add(getClass().getResource("application.css").toExternalForm());
stage.setScene(scene);
stage.show();

}
}

Answer 1

我认为您的问题只是您在 for 循环中创建按钮时从不越过 key_values 数组的第五列。

您应该在迭代时验证每行和每列的长度，以确保您不

例如：

for (int i = 0; i < key_values.length; i++) {
for (int j = 0; j < key_values[i].length; j++) {
btn[i][j] = new Button(key_values[i][j]);

而不是：

for (int i = 0; i < 4; i++) {
for (int j = 0; j < 4; j++) {
btn[i][j] = new Button(key_values[i][j]);