This year's epidemic led to the late start of school. I want to learn and use javafx freely in my self-study at home, so I am going to write a calculator. First, the results are presented, and then the code is analyzed. Here's the source code:
package ff; import java.util.Collections; import java.util.Stack; import javafx.application.Application; import javafx.geometry.Pos; import javafx.scene.Scene; import javafx.scene.control.Button; import javafx.scene.layout.GridPane; import javafx.scene.layout.VBox; import javafx.scene.text.TextAlignment; import javafx.stage.Stage; import javafx.scene.control.Label; import javafx.event.ActionEvent; import javafx.event.EventHandler; import javafx.scene.text.Font; public class Calculator extends Application { StringBuilder lab = new StringBuilder(); Label label1 = new Label(); double q, h, s; String op; @Override public void start(Stage primaryStage) { // String[] button=new String[24]; // for(int i=0;i<24;i++){ //// Button button[i]=new Button(); //// } GridPane pane1 = new GridPane(); pane1.setAlignment(Pos.CENTER); //Add node Button button0 = new Button("mc"); button0.setPrefSize(200, 100);button0.setFont(Font.font(50)); Button button2 = new Button("("); button2.setPrefSize(200, 100);button2.setFont(Font.font(50)); Button button3 = new Button(")"); button3.setPrefSize(200, 100);button3.setFont(Font.font(50)); Button button1 = new Button("mr"); button1.setPrefSize(200, 100);button1.setFont(Font.font(50)); Button button4 = new Button("C"); button4.setPrefSize(200, 100);button4.setFont(Font.font(50)); Button button5 = new Button("/"); button5.setPrefSize(200, 100);button5.setFont(Font.font(50)); Button button6 = new Button("*"); button6.setPrefSize(200, 100);button6.setFont(Font.font(50)); Button button7 = new Button("D"); button7.setPrefSize(200, 100);button7.setFont(Font.font(50)); Button button8 = new Button("7"); button8.setPrefSize(200, 100);button8.setFont(Font.font(50)); Button button9 = new Button("8"); button9.setPrefSize(200, 100);button9.setFont(Font.font(50)); Button button11 = new Button("9"); button11.setPrefSize(200, 100);button11.setFont(Font.font(50)); Button button12 = new Button("-"); button12.setPrefSize(200, 100);button12.setFont(Font.font(50)); Button button13 = new Button("4"); button13.setPrefSize(200, 100);button13.setFont(Font.font(50)); Button button14 = new Button("5"); button14.setPrefSize(200, 100);button14.setFont(Font.font(50)); Button button15 = new Button("6"); button15.setPrefSize(200, 100);button15.setFont(Font.font(50)); Button button16 = new Button("+"); button16.setPrefSize(200, 100);button16.setFont(Font.font(50)); Button button17 = new Button("1"); button17.setPrefSize(200, 100);button17.setFont(Font.font(50)); Button button18 = new Button("2"); button18.setPrefSize(200, 100);button18.setFont(Font.font(50)); Button button19 = new Button("3"); button19.setPrefSize(200, 100);button19.setFont(Font.font(50)); Button button21 = new Button("^"); button21.setPrefSize(200, 100);button21.setFont(Font.font(50)); Button button22 = new Button("%"); button22.setPrefSize(200, 100);button22.setFont(Font.font(50)); Button button23 = new Button("0"); button23.setPrefSize(200, 100);button23.setFont(Font.font(50)); Button button24 = new Button("."); button24.setPrefSize(200, 100);button24.setFont(Font.font(50)); Button button25 = new Button("="); button25.setPrefSize(200, 100);button25.setFont(Font.font(50)); pane1.add(button0, 0, 0); pane1.add(button1, 1, 0); pane1.add(button2, 2, 0); pane1.add(button3, 3, 0); pane1.add(button4, 0, 1); pane1.add(button5, 1, 1); pane1.add(button6, 2, 1); pane1.add(button7, 3, 1); pane1.add(button8, 0, 2); pane1.add(button9, 1, 2); pane1.add(button11, 2, 2); pane1.add(button12, 3, 2); pane1.add(button13, 0, 3); pane1.add(button14, 1, 3); pane1.add(button15, 2, 3); pane1.add(button16, 3, 3); pane1.add(button17, 0, 4); pane1.add(button18, 1, 4); pane1.add(button19, 2, 4); pane1.add(button21, 3, 4); pane1.add(button22, 0, 5); pane1.add(button23, 1, 5); pane1.add(button24, 2, 5); pane1.add(button25, 3, 5); // button0.setOnAction(event -> label1.setText("/"+"")); // button1.setOnAction(event -> label1.setText("/"+"")); // button2.setOnAction(event -> label1.setText("/"+"")); // button3.setOnAction(event -> label1.setText("/"+"")); // //Button4. Setonaction (event - > label1. Settext ("/ +" "); clear operation // button5.setOnAction(event -> label1.setText(label1.getText()+"/")); // button6.setOnAction(event -> label1.setText(label1.getText()+"*")); // //Button7.setonaction (event - > label1. Settext ("/ +" "); / / delete operation // // button8.setOnAction(event -> label1.setText(label1.getText()+"7")); // button9.setOnAction(event -> label1.setText(label1.getText()+"8")); // button11.setOnAction(event -> label1.setText(label1.getText()+"9")); // button12.setOnAction(event -> label1.setText(label1.getText()+"-")); // // button13.setOnAction(event -> label1.setText(label1.getText()+"4")); // button14.setOnAction(event -> label1.setText(label1.getText()+"5")); // button15.setOnAction(event -> label1.setText(label1.getText()+"6")); // button16.setOnAction(event -> label1.setText(label1.getText()+"+")); // // button17.setOnAction(event -> label1.setText(label1.getText()+"1")); // button18.setOnAction(event -> label1.setText(label1.getText()+"2")); // button19.setOnAction(event -> label1.setText(label1.getText()+"3")); // button21.setOnAction(event -> label1.setText(label1.getText()+"^")); // // button22.setOnAction(event -> label1.setText(label1.getText()+"%")); // button23.setOnAction(event -> label1.setText(label1.getText()+"0")); // button24.setOnAction(event -> label1.setText(label1.getText()+".")); // button25.setOnAction(event -> label1.setText(label1.getText()+"= button0.setOnAction(new action()); button1.setOnAction(new action()); button2.setOnAction(new action()); button3.setOnAction(new action()); button4.setOnAction(new action());//clear operation button5.setOnAction(new action()); button6.setOnAction(new action()); button7.setOnAction(new action());//delete operation button8.setOnAction(new action()); button9.setOnAction(new action()); button11.setOnAction(new action()); button12.setOnAction(new action()); button13.setOnAction(new action()); button14.setOnAction(new action()); button15.setOnAction(new action()); button16.setOnAction(new action()); button17.setOnAction(new action()); button18.setOnAction(new action()); button19.setOnAction(new action()); button21.setOnAction(new action()); button22.setOnAction(new action()); button23.setOnAction(new action()); button24.setOnAction(new action()); button25.setOnAction(new action()); label1.setPrefSize(800, 400); label1.setFont(Font.font(50)); label1.setTextAlignment(TextAlignment.LEFT); //VBox pane2=new VBox(label1); //pane2.setAlignment(Pos.BASELINE_LEFT); VBox pane = new VBox(10, label1, pane1); Scene scene = new Scene(pane); primaryStage.setTitle("Calculator"); primaryStage.setScene(scene); primaryStage.show(); } class action implements EventHandler<ActionEvent> { @Override public void handle(ActionEvent event) { String a = event.toString(); String e = a.substring(a.length() - 3, a.length() - 2); char c = a.charAt(a.length() - 3); //System.out.println(c); if (e.equals("0") || e.equals("1") || e.equals("2") || e.equals("3") || e.equals("4") || e.equals("5") || e.equals("6") || e.equals("7") || e.equals("8") || e.equals("9") || e.equals(".")|| e.equals("+") || e.equals("-") || e.equals("*") || e.equals("/")|| e.equals("^")|| e.equals("(")|| e.equals(")") ) { lab.append(e);//Record characters label1.setText(lab.toString()); System.out.println(e); } else if (e.equals("D")) { lab.deleteCharAt(lab.length() - 1); label1.setText(lab.toString()); System.out.println("D"); } else if (e.equals("C")) { lab = new StringBuilder(); label1.setText(lab.toString()); } else if (e.equals("=")){ String expression = lab.toString(); double result = zz.Calculator1.conversion(expression); System.out.println(expression + " = " + result); label1.setText(expression+"="+result); } } } } class ArithHelper { // Default division precision private static final int DEF_DIV_SCALE = 16; // This class cannot be instantiated private ArithHelper() { } public static double add(double v1, double v2) { java.math.BigDecimal b1 = new java.math.BigDecimal(Double.toString(v1)); java.math.BigDecimal b2 = new java.math.BigDecimal(Double.toString(v2)); return b1.add(b2).doubleValue(); } public static double add(String v1, String v2) { java.math.BigDecimal b1 = new java.math.BigDecimal(v1); java.math.BigDecimal b2 = new java.math.BigDecimal(v2); return b1.add(b2).doubleValue(); } public static double sub(double v1, double v2) { java.math.BigDecimal b1 = new java.math.BigDecimal(Double.toString(v1)); java.math.BigDecimal b2 = new java.math.BigDecimal(Double.toString(v2)); return b1.subtract(b2).doubleValue(); } public static double sub(String v1, String v2) { java.math.BigDecimal b1 = new java.math.BigDecimal(v1); java.math.BigDecimal b2 = new java.math.BigDecimal(v2); return b1.subtract(b2).doubleValue(); } public static double mul(double v1, double v2) { java.math.BigDecimal b1 = new java.math.BigDecimal(Double.toString(v1)); java.math.BigDecimal b2 = new java.math.BigDecimal(Double.toString(v2)); return b1.multiply(b2).doubleValue(); } public static double mul(String v1, String v2) { java.math.BigDecimal b1 = new java.math.BigDecimal(v1); java.math.BigDecimal b2 = new java.math.BigDecimal(v2); return b1.multiply(b2).doubleValue(); } public static double div(double v1, double v2) { return div(v1, v2, DEF_DIV_SCALE); } public static double div(String v1, String v2) { java.math.BigDecimal b1 = new java.math.BigDecimal(v1); java.math.BigDecimal b2 = new java.math.BigDecimal(v2); return b1.divide(b2, DEF_DIV_SCALE, java.math.BigDecimal.ROUND_HALF_UP).doubleValue(); } public static double div(double v1, double v2, int scale) { if (scale < 0) { throw new IllegalArgumentException("The scale must be a positive integer or zero"); } java.math.BigDecimal b1 = new java.math.BigDecimal(Double.toString(v1)); java.math.BigDecimal b2 = new java.math.BigDecimal(Double.toString(v2)); return b1.divide(b2, scale, java.math.BigDecimal.ROUND_HALF_UP).doubleValue(); } public static double round(double v, int scale) { if (scale < 0) { throw new IllegalArgumentException("The scale must be a positive integer or zero"); } java.math.BigDecimal b = new java.math.BigDecimal(Double.toString(v)); java.math.BigDecimal one = new java.math.BigDecimal("1"); return b.divide(one, scale, java.math.BigDecimal.ROUND_HALF_UP).doubleValue(); } public static double round(String v, int scale) { if (scale < 0) { throw new IllegalArgumentException("The scale must be a positive integer or zero"); } java.math.BigDecimal b = new java.math.BigDecimal(v); java.math.BigDecimal one = new java.math.BigDecimal("1"); return b.divide(one, scale, java.math.BigDecimal.ROUND_HALF_UP).doubleValue(); } } class Calculator1 { private Stack<String> postfixStack = new Stack<String>(); private Stack<Character> opStack = new Stack<Character>(); private int[] operatPriority = new int[] { 0, 3, 2, 1, -1, 1, 0, 2 };// The priority of operators using ASCII-40 as index public static double conversion(String expression) { double result = 0; zz.Calculator1 cal = new zz.Calculator1(); try { expression = transform(expression); result = cal.calculate(expression); } catch (Exception e) { // e.printStackTrace(); // Operation error returned NaN return 0.0 / 0.0; } // return new String().valueOf(result); return result; } private static String transform(String expression) { char[] arr = expression.toCharArray(); for (int i = 0; i < arr.length; i++) { if (arr[i] == '-') { if (i == 0) { arr[i] = '~'; } else { char c = arr[i - 1]; if (c == '+' || c == '-' || c == '*' || c == '/' || c == '(' || c == 'E' || c == 'e') { arr[i] = '~'; } } } } if(arr[0]=='~'||arr[1]=='('){ arr[0]='-'; return "0"+new String(arr); }else{ return new String(arr); } } public double calculate(String expression) { Stack<String> resultStack = new Stack<String>(); prepare(expression); Collections.reverse(postfixStack);// Reverse suffix stack String firstValue, secondValue, currentValue;// First value, second value and arithmetic operator involved in calculation while (!postfixStack.isEmpty()) { currentValue = postfixStack.pop(); if (!isOperator(currentValue.charAt(0))) {// If it is not an operator, it is stored in the operand stack currentValue = currentValue.replace("~", "-"); resultStack.push(currentValue); } else {// If it is an operator, take two values from the operand stack and participate in the operation together with the value secondValue = resultStack.pop(); firstValue = resultStack.pop(); // Change negative sign to negative sign firstValue = firstValue.replace("~", "-"); secondValue = secondValue.replace("~", "-"); String tempResult = calculate(firstValue, secondValue, currentValue.charAt(0)); resultStack.push(tempResult); } } return Double.valueOf(resultStack.pop()); } private void prepare(String expression) { opStack.push(',');// Operators are put into the comma element at the bottom of the stack, which has the lowest priority char[] arr = expression.toCharArray(); int currentIndex = 0;// Current character position int count = 0;// The length of characters from the last arithmetic operator to the current arithmetic operator is convenient or between char currentOp, peekOp;// Current operator and stack top operator for (int i = 0; i < arr.length; i++) { currentOp = arr[i]; if (isOperator(currentOp)) {// If the current character is an operator if (count > 0) { postfixStack.push(new String(arr, currentIndex, count));// Take the number between two operators } peekOp = opStack.peek(); if (currentOp == ')') {// Remove the element in the operator stack to the suffix stack when an anti bracket is encountered until the left bracket is encountered while (opStack.peek() != '(') { postfixStack.push(String.valueOf(opStack.pop())); } opStack.pop(); } else { while (currentOp != '(' && peekOp != ',' && compare(currentOp, peekOp)) { postfixStack.push(String.valueOf(opStack.pop())); peekOp = opStack.peek(); } opStack.push(currentOp); } count = 0; currentIndex = i + 1; } else { count++; } } if (count > 1 || (count == 1 && !isOperator(arr[currentIndex]))) {// If the last character is not a bracket or other operator, it will be added to the suffix stack postfixStack.push(new String(arr, currentIndex, count)); } while (opStack.peek() != ',') { postfixStack.push(String.valueOf(opStack.pop()));// Add the remaining elements in the operator stack to the suffix stack } } private boolean isOperator(char c) { return c == '+' || c == '-' || c == '*' || c == '/' || c == '(' || c == ')'; } public boolean compare(char cur, char peek) {// If peek priority is higher than cur, return true. By default, peek priority is lower boolean result = false; if (operatPriority[(peek) - 40] >= operatPriority[(cur) - 40]) { result = true; } return result; } private String calculate(String firstValue, String secondValue, char currentOp) { String result = ""; switch (currentOp) { case '+': result = String.valueOf(zz.ArithHelper.add(firstValue, secondValue)); break; case '-': result = String.valueOf(zz.ArithHelper.sub(firstValue, secondValue)); break; case '*': result = String.valueOf(zz.ArithHelper.mul(firstValue, secondValue)); break; case '/': result = String.valueOf(ArithHelper.div(firstValue, secondValue)); break; } return result; } }
``
The screenshot of the operation is as follows:
Here is an example of the operation:
In the process of writing this simple calculator, it is mainly divided into several parts. The first is the interface layout. Then there is the handling of button events. When you click a number, you need to get the information of the button and display the information in the input field. Output the result after the operation.
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