我已经构建了一个简单的计算器，我试图让它成倍增加并正确减去因为我已经有加法和除法工作。我的问题是我无法弄清楚为什么乘法和减法不会起作用。这就是我所拥有的。
import javafx.application.Application;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.geometry.Insets;
import javafx.geometry.Pos;
import javafx.stage.*;
import javafx.scene.*;
import javafx.scene.control.Button;
import javafx.scene.control.TextField;
import javafx.scene.layout.GridPane;
import javafx.scene.layout.HBox;
public class JavaFxCalc extends Application implements
EventHandler<ActionEvent>{
Button [] numButtons;
Insets insets = new Insets(5,5,5,5);
TextField resultsTextField;
HBox topRow,middleRow,lowerRow,bottomRow;
Scene mainScene;
String[] template = {"7","8","9","/",
"4","5","6","*",
"1","2","3","-",
"0",".","=","+",
};
int num1;
String currentOperation;
@Override
public void handle(ActionEvent e){
//numbers 7-9
for(int x =0; x<3; x++){
if(e.getSource() == numButtons[x]){
String numOne = resultsTextField.getText();
resultsTextField.setText(numOne+template[x]);
}
}
//numbers 4-6
for(int x =4; x<7; x++){
if(e.getSource() == numButtons[x]){
String numOne = resultsTextField.getText();
resultsTextField.setText(numOne+template[x]);
}
}
//numbers 1-3
for(int x =7; x<11; x++){
if(e.getSource() == numButtons[x]){
String numOne = resultsTextField.getText();
resultsTextField.setText(numOne+template[x]);
}
}
// 0 and a decimal
for(int x =11; x<14; x++){
if(e.getSource() == numButtons[x]){
String numOne = resultsTextField.getText();
resultsTextField.setText(numOne+template[x]);
}
}
// operation
for(int x =0; x<16; x++) {
if(e.getSource() == numButtons[7] || e.getSource() == numButtons[3] ||
e.getSource() == numButtons[11] || e.getSource() == numButtons[15]){
String firstNum = resultsTextField.getText();
num1 = Integer.parseInt(firstNum);
resultsTextField.setText("");
currentOperation = ((Button) e.getSource()).getText();
}
}
// Equals sign
for(int x =14; x<=15; x++){
if(e.getSource() == numButtons[x]){
String secondNum = resultsTextField.getText();
Integer num2 = Integer.parseInt(secondNum);
switch (currentOperation) {
case "+":
num1 = num1 + num2;
resultsTextField.setText(String.valueOf(num1));
break;
case "-":
num1 = num1 - num2;
resultsTextField.setText(String.valueOf(num1));
break;
case "*":
num1 = num1 * num2;
resultsTextField.setText(String.valueOf(num1));
break;
case "/":
num1 = num1 / num2;
resultsTextField.setText(String.valueOf(num1));
break;
default:
break;
}
}
}
}
@Override
public void start(Stage primaryStage)throws Exception{
primaryStage.setTitle("Javafx Calc");
primaryStage.setResizable(false);
primaryStage.sizeToScene();
GridPane mainPane = new GridPane();
mainScene = new Scene(mainPane);
resultsTextField = new TextField();
resultsTextField.setPrefSize(100, 50);
mainPane.setPadding(insets);
mainPane.setConstraints(resultsTextField,0,0);
//adds buttons 7-9 and division sign to top row and adds top row to
mainPane
topRow = new HBox(5);
topRow.setAlignment(Pos.CENTER);
topRow.setPadding(insets);
numButtons = new Button[17];
for(int x=0; x < 4; x++){
numButtons[x] = new Button();
numButtons[x].setText(template[x]);
topRow.getChildren().addAll(numButtons[x]);
}
mainPane.setConstraints(topRow,0,1);
//adds buttons 4-6 and multiplication sign to middle row and adds middle
row to mainPane
middleRow = new HBox(5);
middleRow.setAlignment(Pos.CENTER);
middleRow.setPadding(insets);
for(int x=4; x < 8; x++){
numButtons[x] = new Button();
numButtons[x].setText(template[x]);
middleRow.getChildren().addAll(numButtons[x]);
}
mainPane.setConstraints(middleRow,0,2);
//adds 1-3 and adds minus sign to lowerRow and adds lower row to mainPane
lowerRow = new HBox(5);
lowerRow.setAlignment(Pos.CENTER);
lowerRow.setPadding(insets);
for(int x=8; x < 12; x++){
numButtons[x] = new Button();
numButtons[x].setText(template[x]);
lowerRow.getChildren().addAll(numButtons[x]);
}
mainPane.setConstraints(lowerRow,0,3);
//adds 0, . , = and + to the bottom row and adds the bottom row to the
mainPane
bottomRow = new HBox(5);
bottomRow.setAlignment(Pos.CENTER);
bottomRow.setPadding(insets);
for(int x=12; x < 16; x++){
numButtons[x] = new Button();
numButtons[x].setText(template[x]);
bottomRow.getChildren().addAll(numButtons[x]);
}
mainPane.setConstraints(bottomRow,0,4);
//sets preffered size for all buttons and adds action listeners to each
button
for(int x =0; x < 16; x++){
numButtons[x].setPrefSize(50,30);
numButtons[x].setOnAction(this);
}
mainPane.getChildren().addAll(resultsTextField,topRow
,middleRow,lowerRow,bottomRow);
primaryStage.setScene(mainScene);
primaryStage.show();
}
public static void main(String[] args) {
launch(args);
}
}
答案 0 :(得分：0)
您的代码的主要问题来自于您正在处理一个大事件处理程序中的所有内容。
for循环会导致针对单个事件执行多个操作，从而导致多个问题。
您应该对其进行重组，以便为每个特定任务添加单独的事件处理程序，以便每个处理程序都可以执行特定的操作，而不会过滤掉它不应该执行的所有操作 - 这样可以更容易地跟踪。< / p>
public class JavaFxCalc extends Application {
// All members are the same as your original code
// public void handle(ActionEvent e) has been removed
@Override
public void start(Stage primaryStage) throws Exception {
// All setup code is the same up until the for-loop below
//sets preffered size for all buttons
for (int x = 0; x < 16; x++) {
numButtons[x].setPrefSize(50, 30);
}
// Add action handlers for the number buttons
for (int x = 0; x < 14; x++) {
// We need a final variable for the event handler
final int index = x;
if(x == 3 || x == 7 || x == 11) {
// Skip the operation buttons, we won't hit 15 (+) here since the loop only goes to 13 (.)
continue;
}
// This will create one unique event handler for each button.
// Since we have the final index variable here we don't need to
// iterate over the buttons to find the correct template position - we already know it
numButtons[x].setOnAction(new EventHandler<ActionEvent>() {
@Override
public void handle(final ActionEvent event) {
String numOne = resultsTextField.getText();
resultsTextField.setText(numOne + template[index]);
}
});
}
// Add action handlers for the operation buttons
for (int x : new int[]{3, 7, 11, 15}) {
numButtons[x].setOnAction(new EventHandler<ActionEvent>() {
@Override
public void handle(final ActionEvent event) {
String firstNum = resultsTextField.getText();
num1 = Integer.parseInt(firstNum);
resultsTextField.setText("");
currentOperation = ((Button) event.getSource()).getText();
}
});
}
// Add action handler for the equals button
numButtons[14].setOnAction(new EventHandler<ActionEvent>() {
@Override
public void handle(final ActionEvent event) {
String secondNum = resultsTextField.getText();
int num2 = Integer.parseInt(secondNum);
switch (currentOperation) {
case "+":
num1 = num1 + num2;
resultsTextField.setText(String.valueOf(num1));
break;
case "-":
num1 = num1 - num2;
resultsTextField.setText(String.valueOf(num1));
break;
case "*":
num1 = num1 * num2;
resultsTextField.setText(String.valueOf(num1));
break;
case "/":
num1 = num1 / num2;
resultsTextField.setText(String.valueOf(num1));
break;
default:
break;
}
}
});
mainPane.getChildren().addAll(resultsTextField, topRow
, middleRow, lowerRow, bottomRow);
primaryStage.setScene(mainScene);
primaryStage.show();
}
public static void main(String[] args) {
launch(args);
}
}