在 JApplet 上运行的 JPanel [英] JPanel running on a JApplet

问题描述

我正在设计一个 JApplet，基本上这个小程序将允许用户绘制二次方程图，并插入 x 轴和 y 轴的范围.但要达到这一点，还有很多工作要做.

I am designing a JApplet, and basically this applet will allow a user to draw a quadratic equation graph and it inserts the ranges of both x-axis and y-axis. But there is much more to do to reach that point.

我还在设计界面.

这是我的代码:

import java.awt.Dimension;

import javax.swing.BoxLayout;
import javax.swing.JApplet;
import javax.swing.JButton;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollPane;


public class Applet extends JApplet {
    JPanel p1;
    JPanel p2;
    JPanel p3;

    JScrollPane s1;

    public Applet() {

    p1 = new JPanel();
    p2 = new JPanel();
    p3 = new JPanel();

    s1 = new JScrollPane(p3,s1.VERTICAL_SCROLLBAR_ALWAYS,s1.HORIZONTAL_SCROLLBAR_ALWAYS);
    }

    @Override
    public void init() {
    super.init();

    for(int i=0;i<100;i++)
    {
        p3.add(new JButton("Hello"));
        p3.add(new JLabel("blah"));
        p3.add(new JButton("Sup"));
    }

    p1.setPreferredSize(new Dimension(this.getWidth(), this.getHeight()));
    p2.setPreferredSize(new Dimension(this.getWidth(),(int) (this.getHeight()*0.6667)));

    p3.setLayout(new BoxLayout(p3,BoxLayout.PAGE_AXIS));
    s1.setPreferredSize(new Dimension(this.getWidth(),(int)(this.getHeight()*0.33333)));

    p1.add(p2);
    p1.add(s1);

    this.add(p1);
    }

}

推荐答案

1. 要将 x 轴和 y 轴控件放在一起，您应该有两个面板，一个面板包括 x 轴的标签和文本字段，一个是 y 轴的标签和文本字段在另一个.然后，您可以将它们添加到垂直对齐的面板中.(例如，Box.createVerticalBox())

您可以使您的 graph.java 成为Plot"和Refine"按钮的 ActionListener.在 graph.java 的 actionPerformed 方法中，您可以启动重绘，从 'ControlsB' 实例收集范围.

You can make your graph.java an ActionListener of the 'Plot' and 'Refine' buttons. In the actionPerformed method of graph.java, you can initiate a repaint, gathering the ranges from the 'ControlsB' instance.

回复您的评论...

'如何添加另一个面板以便我将 x 轴放置在 y 轴上方'

这可以像(在 ControlsB.java 中)一样简单:

this can be as simple as (in ControlsB.java):

b = Box.createHorizontalBox();
b.add(new JLabel("Please enter range:  "));

Box b0 = Box.createVerticalBox();//create a vertical box to stack the controls

Box b1 = Box.createHorizontalBox(); // create a horizontal box for the x-axis

b1.add(new JLabel(" x-axis "));
b1.add(new JLabel("from"));
JTextField f1 = new JTextField("-5");
f1.setMaximumSize(new Dimension(100,30));
b1.add(f1);
b1.add(new JLabel(" to "));
JTextField f2 = new JTextField("5");
f2.setMaximumSize(new Dimension(100,30));
b1.add(f2);
b1.add(new JLabel(".   "));

Box b2 = Box.createHorizontalBox(); // create a second horizontal box for the y-axis
b2.add(new JLabel("y-axis "));
b2.add(new JLabel("from"));
JTextField f3 = new JTextField("5");
f3.setMaximumSize(new Dimension(100,30));
b2.add(f3);
b2.add(new JLabel("to"));
JTextField f4 = new JTextField("-5");
f4.setMaximumSize(new Dimension(100,30));
b2.add(f4);

b0.add(b1); // add the x-axis to the vertical box
b0.add(b2); // add the y-axis to the vertical box
b.add(b0);  // add the vertical box to the parent

b.add(new JButton("Plot"));
b.add(new JButton("Refine"));
add(b); //is this necessary?
}

'以及如何从 ControlsB 实例收集范围...'

您应该查看 ActionListener>本教程了解如何在单独的类中让按钮点击事件触发动作.

You should look into ActionListeners in this tutorial to understand how to make the button click events trigger action in a separate class.

另外，两个批评:

1. 在您的主类 GraphApplet 中，您正在创建一个 Box，然后再将其传递给每个 ControlsA 和 ControlsB 的构造函数.在构造函数中，您然后重新分配您传入的 Box.我认为您不需要这样做.要么在 GraphApplet 中创建正确对齐的框，将其传入且不重新分配，或者根本不传入任何内容.

1. in your main class, GraphApplet, you are creating a Box before passing it into each of ControlsA and ControlsB's constructor. In the constructor, you then reassign the Box that you've passed in. I don't think that you need to do that. Either create the correctly aligned box in GraphApplet, pass that in and don't reassign, or don't pass anything in at all.

您的ControlsA 和ControlsB 类都扩展了JPanel.尽管您在构造函数的末尾将 Box 容器添加到每个容器中遇到了麻烦，但您永远不会将这些 Controls+ 对象添加到任何父容器中.在您当前的实现中，我建议不需要扩展 JPanel.

Your ControlsA and ControlsB classes both extend JPanel. Although you go to the trouble of adding your Box containers to each of these at the end of their constructors, you don't ever add those Controls+ objects to any parent container. In your current implementation, i would suggest that extending JPanel is not necessary.

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