在JavaFX中為計算器創建一個退格按鈕

Question

我正在嘗試創建一個JavaFX計算器，這是一個非常基本的計算器，但是我不確定如何實現退格鍵。

private void makeBackspaceButton(Button button) {
    button.setStyle("-fx-base: ivory;");
    button.setOnAction(new EventHandler<ActionEvent>() {
        @Override
        public void handle(ActionEvent actionEvent) {
            value.set(value.get());
        }
    });

}

我一生都無法想到刪除最后輸入的值的方法。 因此，如果輸入值89，則僅刪除最后一個數字（9）。 有沒有辦法以這種格式使用它，或者我需要更改格式。 我的完整代碼在下面，尚未完成。

import javafx.application.Application;
import javafx.beans.binding.Bindings;
import javafx.beans.property.*;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.control.*;
import javafx.scene.input.KeyEvent;
import javafx.scene.layout.*;
import javafx.stage.Stage;
import javafx.stage.StageStyle;

import java.util.HashMap;
import java.util.Map;

// a simple JavaFX calculator.
public class Calcy extends Application {

//implementing the template if how i would like the buttons to look like
private static final String[][] template = {
    {"c", "%", "√", "←"},
    {"7", "8", "9", "/"},
    {"4", "5", "6", "*"},
    {"1", "2", "3", "-"},
    {"0", ".", "=", "+"}
};

private final Map<String, Button> accelerators = new HashMap<>();


private DoubleProperty stackValue = new SimpleDoubleProperty();
private DoubleProperty value = new SimpleDoubleProperty();

private enum Op {

    NOOP, ADD, SUBTRACT, MULTIPLY, DIVIDE
}

private Op curOp = Op.NOOP;
private Op stackOp = Op.NOOP;

public static void main(String[] args) {
    launch(args);
}

@Override
public void start(Stage stage) {
    final TextField screen = createScreen();
    final TilePane buttons = createButtons();

    stage.setTitle("Thank goodness for a calculator!");
    stage.initStyle(StageStyle.UTILITY);
    stage.setResizable(false);
    stage.setScene(new Scene(createLayout(screen, buttons)));
    stage.show();
}

private VBox createLayout(TextField screen, TilePane buttons) {
    final VBox layout = new VBox(20);
    layout.setAlignment(Pos.CENTER);
    layout.setStyle("-fx-background-color: floralwhite; -fx-padding: 20; -fx-font-size: 20;");
    layout.getChildren().setAll(screen, buttons);
    handleAccelerators(layout);
    screen.prefWidthProperty().bind(buttons.widthProperty());
    return layout;
}

private void handleAccelerators(VBox layout) {
    layout.addEventFilter(KeyEvent.KEY_PRESSED, new EventHandler<KeyEvent>() {
        @Override
        public void handle(KeyEvent keyEvent) {
            Button activated = accelerators.get(keyEvent.getText());
            if (activated != null) {
                activated.fire();
            }
        }
    });
}

private TextField createScreen() {
    final TextField screen = new TextField();
    screen.setStyle("-fx-background-color: lightgrey;");
    screen.setAlignment(Pos.CENTER_RIGHT);
    screen.setEditable(false);
    screen.textProperty().bind(Bindings.format("%.2f", value));
    return screen;
}

private TilePane createButtons() {
    TilePane buttons = new TilePane();
    buttons.setVgap(7);
    buttons.setHgap(7);
    buttons.setPrefColumns(template[0].length);
    for (String[] r : template) {
        for (String s : r) {
            buttons.getChildren().add(createButton(s));
        }
    }
    return buttons;
}

private Button createButton(final String s) {
    Button button = makeStandardButton(s);

    if (s.matches("[0-9]")) {
        makeNumericButton(s, button);
    } else {
        final ObjectProperty<Op> triggerOp = determineOperand(s);
        if (triggerOp.get() != Op.NOOP) {
            makeOperandButton(button, triggerOp);
        } else if ("c".equals(s)) {
            makeClearButton(button);
        } else if ("=".equals(s)) {
            makeEqualsButton(button);
        } else if ("←".equals(s)) {
            makeBackspaceButton(button);
        } else if ("%".equals(s)) {
            makePercentageButton(button);
        } else if ("√".equals(s)) {
            makeSquarerootButton(button);
        } else if (".".equals(s)) {
            makePointButton(button);
        }
    }

    return button;
}

private ObjectProperty<Op> determineOperand(String s) {
    final ObjectProperty<Op> triggerOp = new SimpleObjectProperty<>(Op.NOOP);
    switch (s) {
        case "+":
            triggerOp.set(Op.ADD);
            break;
        case "-":
            triggerOp.set(Op.SUBTRACT);
            break;
        case "*":
            triggerOp.set(Op.MULTIPLY);
            break;
        case "/":
            triggerOp.set(Op.DIVIDE);
            break;
        case "%":

    }
    return triggerOp;
}

private void makeOperandButton(Button button, final ObjectProperty<Op> triggerOp) {
    button.setStyle("-fx-base: ivory;");
    button.setOnAction(new EventHandler<ActionEvent>() {
        @Override
        public void handle(ActionEvent actionEvent) {
            curOp = triggerOp.get();
        }
    });
}

private Button makeStandardButton(String s) {
    Button button = new Button(s);
    button.setStyle("-fx-base: ivory;");
    accelerators.put(s, button);
    button.setMaxSize(Double.MAX_VALUE, Double.MAX_VALUE);
    return button;
}

private void makeNumericButton(final String s, Button button) {
    button.setOnAction(new EventHandler<ActionEvent>() {
        @Override
        public void handle(ActionEvent actionEvent) {
            if (curOp == Op.NOOP) {
                value.set(value.get() * 10 + Integer.parseInt(s));
            } else {
                stackValue.set(value.get());
                value.set(Integer.parseInt(s));
                stackOp = curOp;
                curOp = Op.NOOP;
            }
        }
    });
}

private void makeClearButton(Button button) {
    button.setStyle("-fx-base: ivory;");
    button.setOnAction(new EventHandler<ActionEvent>() {
        @Override
        public void handle(ActionEvent actionEvent) {
            value.set(0);
        }
    });
}

private void makeBackspaceButton(Button button) {
    button.setStyle("-fx-base: ivory;");
    button.setOnAction(new EventHandler<ActionEvent>() {
        @Override
        public void handle(ActionEvent actionEvent) {
            value.set(value.get());
        }
    });

}

private void makeSquarerootButton(Button button) {
    button.setStyle("-fx-base: ivory;");
}

private void makePercentageButton(Button button) {
    button.setStyle("-fx-base: ivory;");
}

private void makePointButton(Button button) {
    button.setStyle("-fx-base: ivory;");
}

private void makeEqualsButton(Button button) {
    button.setStyle("-fx-base: ivory;");
    button.setOnAction(new EventHandler<ActionEvent>() {
        @Override
        public void handle(ActionEvent actionEvent) {
            switch (stackOp) {
                case ADD:
                    value.set(stackValue.get() + value.get());
                    break;
                case SUBTRACT:
                    value.set(stackValue.get() - value.get());
                    break;
                case MULTIPLY:
                    value.set(stackValue.get() * value.get());
                    break;
                case DIVIDE:
                    value.set(stackValue.get() / value.get());
                    break;
            }
        }
    });
}

}

Answer 1

您可以在退格按鈕的操作方法內添加以下行。 這只是我的正常操作。

獲取號碼，但最后輸入的號碼可以通過

(int)value.get()/10

以后，小數部分可以通過

value.get() - (int)value.get())

所以這就是

button.setOnAction(new EventHandler<ActionEvent>() {
    @Override
    public void handle(ActionEvent actionEvent) {
        value.set((int)value.get()/10 + 
        /**
        * To get the decimal part
        */
        value.get() - (int)value.get());
    }
});

小數部分仍然無法在您的計算器上運行，請對其進行修復。 完成后，您將不得不更改方法以考慮十進制之前和之后的值！

Answer 2

私有void BackButtonActionPerformed（java.awt.event.ActionEvent evt）{

    if (OutputTextField.getText().length()>0){
        StringBuffer sb = new StringBuffer(OutputTextField.getText());
        sb = sb.deleteCharAt(OutputTextField.getText().length()-1);
        OutputTextField.setText(sb.toString());
    }
}