动态向JPanel添加组件 [英] Dynamically adding components to JPanel

问题描述

我正在尝试将某些组件动态添加到JPanel中，但是不幸的是它们没有出现.我只看到构造器中添加的那些.

I'm trying to dynamically add some components to a JPanel, but unfortunatelly they don't appear. I only see the ones added in the constuctor.

更新版本(添加一个新的JPanel，所有组件都将存在于其中):

Updated version (adding a new JPanel, where all the components will be):

public class View extends JPanel {

JPanel panel = new JPanel();
JLabel label;
JLabel labels[];
JButton b1 = new JButton("OK");

public View() {
   this.setLayout(new FlowLayout());
   this.add(panel); // adding a new JPanel
   label = new JLabel("My label");
   panel.add(label);  // adding label to the new panel (this one works)
}


public void showLabels() {
  System.out.println("function showLabels called");

  labels = new JLabel[5];

  for (int i = 0; i < 5; i++) {
      labels[i] = new JLabel("Label: " + i);
      panel.add(labels[i]); // this one doesn't work
  }
  panel.add(b1); // this one doesn't work, too
    this.validate(); // validating this class (parent container)
    panel.validate(); // validating the panel, where all the components are
  }
}

不幸的是，一切都没有改变.

Unfortunatelly nothing changed.

推荐答案

调用嵌套布局中所示，在父容器上为％28％29"rel =" nofollow noreferrer> validate() 例子.左下方的那些标签是动态添加的.请注意，调用pack()可能会导致GUI的大小发生变化，而调用validate()不会.如果需要以调整GUI的大小，请调用pack()，否则调用validate().

Call validate() on the parent container, as shown in the Nested Layout Example. Those labels on the lower left are added dynamically. Note that calling pack() might cause the size of the GUI to change, whereas calling validate() won't. If you need to get the GUI to resize - call pack(), else call validate().

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