移除节点后在GridPane中未更新。

huangapple
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英文:

Removing node does not update in GridPane

问题

我试图从GridPane中移除一个节点，但当我执行gridPane.getChildren().remove(node)时，UI似乎没有更新。当TextField为空时，会出现一个标签，当填写后，它应该显示已添加订单。但是，当空的TextField标签出现时，实际填写它们后，请填写所有字段不会消失，而已添加订单正好位于其上方。

  1. import java.awt.*;
  2. import java.util.ArrayList;
  3. import javafx.event.EventHandler;
  4. import javafx.geometry.HPos;
  5. import javafx.geometry.Insets;
  6. import javafx.scene.input.MouseEvent;
  7. import javafx.scene.layout.HBox;
  8. import javafx.event.ActionEvent;
  9. import javafx.scene.layout.GridPane;
  10. import javafx.scene.layout.Region;
  11. import javafx.scene.text.Text;
  12. import javafx.geometry.Pos;
  13. import javafx.scene.control.TextField;
  14. import javafx.scene.control.Label;
  15. import javafx.scene.control.Button;
  16. import javafx.scene.control.TextArea;
  17. import javafx.scene.paint.Color;
  18. import javax.swing.*;
  20. public class InputPane extends HBox
  21. {
  22.     ArrayList<Order> orderList;
  24.     private HandlePane handlePane;
  26.     TextField textField1 = new TextField();
  27.     TextField textField2 = new TextField();
  28.     TextField textField3 = new TextField();
  30.     Label prodName, quantity, price, fill = new Label();
  32.     Button place_an_order;
  34.     GridPane gridPane;
  35.     TextArea textArea;
  37.     public InputPane(ArrayList<Order> list, HandlePane pane)
  38.     {
  39.         this.orderList = list;
  40.         this.handlePane = pane;
  42.         prodName = new Label("Prod. Name");
  43.         quantity = new Label ("Quantity");
  44.         price = new Label ("Price($)");
  45.         prodName.setMinWidth(Region.USE_PREF_SIZE);
  47.         place_an_order = new Button("Place an Order");
  49.         gridPane = new GridPane();
  50.         gridPane.setPadding(new Insets(10,20,10,20));
  51.         gridPane.setVgap(10);
  52.         gridPane.setHgap(10);
  54.         gridPane.add(prodName, 0, 1);
  55.         gridPane.add(textField1, 1,1);
  56.         gridPane.add(quantity, 0,2);
  57.         gridPane.add(textField2, 1,2);
  58.         gridPane.add(price, 0,3);
  59.         gridPane.add(textField3, 1,3);
  60.         gridPane.add(place_an_order, 1,4);
  62.         textArea = new TextArea();
  63.         textArea.setText("No order");
  64.         textArea.setPrefSize(320,120);
  66.         this.getChildren().addAll(gridPane, textArea);
  68.         ButtonHandler handler = new ButtonHandler();
  69.         place_an_order.setOnAction(handler);
  70.     }
  72.     private class ButtonHandler implements EventHandler<ActionEvent>{
  73.         public void handle(ActionEvent e){
  74.             String productStr = textField1.getText().trim();
  75.             String quantityStr = textField2.getText().trim();
  76.             String priceStr = textField3.getText().trim();
  78.             fill.setTextFill(Color.web("FF0000"));
  79.             fill.setMinWidth(Region.USE_PREF_SIZE);
  81.             if (productStr.isEmpty() || quantityStr.isEmpty() || priceStr.isEmpty())
  82.             {
  83.                 fill.setText("Please fill all the fields");
  84.                 fill.setTextFill(Color.web("FF0000"));
  85.                 fill.setMinWidth(Region.USE_PREF_SIZE);
  86.             }else{
  87.                 fill.setText("Order added");
  88.                 fill.setTextFill(Color.web("#000000"));
  89.                 gridPane.add(fill, 0,0);
  90.             }
  91.         }
  92.     }
  93. }
英文:

I'm trying to remove a node from the GridPane but when I do gridPane.getChildren().remove(node), it doesn't seem to be updated in the UI. I have a label that comes up when there's an empty TextField, and when they are filled it should say Order added. But when the empty TextField label comes up and when I actually fill them up, Please fill all fields doesn't go away and Order added is just right on top of it.

  1. import java.awt.*;
  2. import java.util.ArrayList;
  3. import javafx.event.EventHandler;
  4. import javafx.geometry.HPos;
  5. import javafx.geometry.Insets;
  6. import javafx.scene.input.MouseEvent;
  7. import javafx.scene.layout.HBox;
  8. import javafx.event.ActionEvent;
  9. import javafx.scene.layout.GridPane;
  10. import javafx.scene.layout.Region;
  11. import javafx.scene.text.Text;
  12. import javafx.geometry.Pos;
  13. import javafx.scene.control.TextField;
  14. import javafx.scene.control.Label;
  15. import javafx.scene.control.Button;
  16. import javafx.scene.control.TextArea;
  17. import javafx.scene.paint.Color;
  18. import javax.swing.*;
  19. public class InputPane extends HBox
  20. {
  21. ArrayList &lt; Order &gt; orderList;
  22. private HandlePane handlePane;
  23. TextField textField1 = new TextField();
  24. TextField textField2 = new TextField();
  25. TextField textField3 = new TextField();
  26. Label prodName, quantity, price, fill = new Label();
  27. Button place_an_order;
  28. GridPane gridPane;
  29. TextArea textArea;
  30. public InputPane(ArrayList &lt; Order &gt; list, HandlePane pane)
  31. {
  32. this.orderList = list;
  33. this.handlePane = pane;
  34. prodName = new Label(&quot;Prod. Name&quot;);
  35. quantity = new Label (&quot;Quantity&quot;);
  36. price = new Label (&quot;Price($)&quot;);
  37. prodName.setMinWidth(Region.USE_PREF_SIZE);
  38. place_an_order = new Button(&quot;Place an Order&quot;);
  39. gridPane = new GridPane();
  40. gridPane.setPadding(new Insets(10,20,10,20));
  41. gridPane.setVgap(10);
  42. gridPane.setHgap(10);
  43. gridPane.add(prodName, 0, 1);
  44. gridPane.add(textField1, 1,1);
  45. gridPane.add(quantity, 0,2);
  46. gridPane.add(textField2, 1,2);
  47. gridPane.add(price, 0,3);
  48. gridPane.add(textField3, 1,3);
  49. gridPane.add(place_an_order, 1,4);
  50. textArea = new TextArea();
  51. textArea.setText(&quot;No order&quot;);
  52. textArea.setPrefSize(320,120);
  53. this.getChildren().addAll(gridPane, textArea);
  54. ButtonHandler handler = new ButtonHandler();
  55. place_an_order.setOnAction(handler);
  56. }
  57. private class ButtonHandler implements EventHandler &lt; ActionEvent &gt;{
  58. public void handle(ActionEvent e){
  59. String productStr = textField1.getText().trim();
  60. String quantityStr = textField2.getText().trim();
  61. String priceStr = textField3.getText().trim();
  62. fill.setTextFill(Color.web(&quot;FF0000&quot;));
  63. fill.setMinWidth(Region.USE_PREF_SIZE);
  64. if (productStr.isEmpty() || quantityStr.isEmpty() || priceStr.isEmpty())
  65. {
  66. fill.setText(&quot;Please fill all the fields&quot;);
  67. fill.setTextFill(Color.web(&quot;FF0000&quot;));
  68. fill.setMinWidth(Region.USE_PREF_SIZE);
  69. }else{
  70. fill.setText(&quot;Order added&quot;);
  71. fill.setTextFill(Color.web(&quot;#000000&quot;));
  72. gridPane.add(fill, 0,0);
  73. }
  74. }
  75. }
  76. }

With empty fields:

移除节点后在GridPane中未更新。

With filled fields:

移除节点后在GridPane中未更新。

答案1

得分: 1

每次您点击按钮时，handle 方法：

  1. 创建一个名为 fill 的新 Label 实例。

  2. 检查所有字段是否已填写完整。

当该条件为真时，它执行 gridPane.getChildren().remove(fill);，但是 fill 刚刚在步骤1中被创建，并且还没有成为 gridPane 的子元素，所以这个指令 不会做任何操作。

当执行指令 gridPane.add(fill, 0,0); 时，您将 fill 标签（带有文本“Order added”）添加到网格窗格中，执行 handle 多次时会出现这种 叠加效果。

这不是 JavaFX 的错误；GridPane 的每个单元格的行为类似于 StackPane，因此您可以很好地 将标签叠加在一起。

我建议您：

  • 删除 gridPane.getChildren().remove(fill); 这条指令。

  • 将 gridPane.add(fill, 0, 0); 移到 handle 方法之外；您必须在组件初始化时执行这一行代码 一次。

  1. private class ButtonHandler implements EventHandler<ActionEvent> {
  2.     Label fill;
  4.     public ButtonHandler() {
  5.         fill = new Label();
  6.         fill.setTextFill(Color.web("FF0000"));
  7.         fill.setMinWidth(Region.USE_PREF_SIZE);
  9.         gridPane.add(fill, 0, 0);
  10.     }
  12.     public void handle(ActionEvent e) {
  13.         String productStr = textField1.getText().trim();
  14.         String quantityStr = textField2.getText().trim();
  15.         String priceStr = textField3.getText().trim();
  17.         if (productStr.isEmpty() || quantityStr.isEmpty() || priceStr.isEmpty()) {
  18.             fill.setText("Please fill all the fields");
  19.             fill.setTextFill(Color.web("FF0000"));
  20.         } else {
  21.             fill.setText("Order added");
  22.             fill.setTextFill(Color.web("#000000"));
  23.         }
  24.     }
  25. }
英文:

Each time you click on your button, the handle method:

  1. Instantiates a new Label instance called fill

  2. Checks whether all fields are completed.

When that condition is true, it executes gridPane.getChildren().remove(fill);, but fill has just been instantiated in step 1 and is not a children of gridPane yet, so the instruction doesn't do anything.

When the instruction gridPane.add(fill, 0,0); is executed, you add the fill label (with text "Order added") inside the grid pane and you get this overlay effect when executing handle several times.

This is not a JavaFX bug; each cell of a GridPane behaves line a StackPane, so you can perfectly add labels above each other.

I would recommend you to:

  • Remove the gridPane.getChildren().remove(fill); instruction

  • Move gridPane.add(fill, 0, 0); outside the handle method; you have to execute this line once (at the initialization of the component).

    1. private class ButtonHandler implements EventHandler &lt;ActionEvent&gt; {
    2. Label fill;
    3. public ButtonHandler() {
    4. fill = new Label();
    5. fill.setTextFill(Color.web(&quot;FF0000&quot;));
    6. fill.setMinWidth(Region.USE_PREF_SIZE);
    7. gridPane.add(fill, 0, 0);
    8. }
    9. public void handle(ActionEvent e) {
    10. String productStr = textField1.getText().trim();
    11. String quantityStr = textField2.getText().trim();
    12. String priceStr = textField3.getText().trim();
    13. if (productStr.isEmpty() || quantityStr.isEmpty() || priceStr.isEmpty()) {
    14. fill.setText(&quot;Please fill all the fields&quot;);
    15. fill.setTextFill(Color.web(&quot;FF0000&quot;));
    16. } else {
    17. fill.setText(&quot;Order added&quot;);
    18. fill.setTextFill(Color.web(&quot;#000000&quot;));
    19. }
    20. }
    21. }

huangapple
  • 本文由 发表于 2020年10月1日 12:17:56
  • 转载请务必保留本文链接：https://go.coder-hub.com/64148994.html
  • java
  • javafx
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