java - 从一个类中更改另一个类中的变量

Question

FNAKLNFDKA.java

import java.awt.*;
import javax.swing.*;

public class GraphApplet extends JApplet{

private static final long serialVersionUID = 1L;
public static Graphics p;

public void init(){

    SwingUtilities.invokeLater(new Runnable() {
        public void run() {


    });
  }
}

FANKJ.java

import java.awt.*;
import java.awt.geom.*;
import javax.swing.*;

class FASKHF extends JPanel {


public static Graphics p;
private static final long serialVersionUID = 1L;

public Graph(){
    this.setBackground(Color.yellow);
}

@Override
public Dimension getPreferredSize()
{   
    return (new Dimension(560,560));
}

public static void updateGraph() {


    repaint();
}



public void paint(Graphics F) {



    //line co-ordinates
    //the numbers represent the number of boxes on the graph
    //1st line on the l/h side
    int xstart1 = 2;
    int ystart1 = 3;

    int xfinish1 = 1;
    int yfinish1 = 9;

    //2nd line on the r/h side
    int xstart2 = 8;
    int ystart2 = 3;

    int xfinish2 = 9;
    int yfinish2 = 9;

  //drawing upper arc
    int arcX = 2;
    int arcY = 1;
    int imagRectWid = 6;
    int imagRectHei = 4;
    int startAngle = 0;
    int arcAngle = 180;

    //other



    f = xaxis22;
    g = xaxis11;

    //to be assigned later.
    //the values of xaxis and yaxis need to be separated
    //yaxis3 = 5;
    //yaxis4 = -5;

    //change -ve num to +ve
    int g3 = Math.abs(g);

    int a1 = g3 + f;
    int b1 = a1;

    int d = (appletWidth / a1);
    int e = (Height / b1);

    /**
     to determine the
     ammount of pixles there
     is in each box of the
     graph, both y-axis and 
     x-axis
     */
    int xbox = x1 / 10;
    int ybox = y1 / 10;

    //line variables
    //the xstart, ystart, etc represent the number of boxes

    //top point of the line on the graph
    px1 = xbox * xstart1;//start x
    py1 = ybox * ystart1;//start y

    //lowwer point of the line on the graph
    px = xbox * xfinish1;//finish x
    py = ybox * yfinish1;//finish y

    //other line on the right hand side
    p2x = xbox * xstart2;
    p2y = ybox * ystart2;

    p2x2 = xbox * xfinish2;
    p2y2 = ybox * yfinish2;

    //drawing arc
    int arcBoxX = arcX * xbox;
    int arcBoxY = arcY * ybox;
    int arcBoxWidth = imagRectWid * xbox;
    int arcBoxHeight = imagRectHei * ybox;


    //draw y-axis numbers 
    //(+ve)
    while(f != 0){
        String s = String.valueOf(f);
        p.drawString(s,(x + 5),m + 13);
        m = m + b;
        f = f - 1;
    }
    //(-ve)
    m2 = y;
    while(f2 != g-1){
        String u = String.valueOf(f2);
        p.drawString(u,(x + 5),m2 - 3);
        m2 = m2 + b;
        f2 = f2 - 1;
    }
    //draw x-axis numbers.
    //(-ve)
    while(g != 0){
        String t = String.valueOf(g);
        p.drawString(t,n,y - 5);
        n = n + a;
        g = g + 1;
    }
    //(+ve)
    n2 = x + a;
    while(g2 != g3+1){
        String vw = String.valueOf(g2);
        p.drawString(vw,n2 -10,y - 5);
        n2 = n2 + a;
        g2 = g2 + 1;
    }

    BasicStroke aLine2 = new BasicStroke(1.0F,
                                         BasicStroke.CAP_ROUND,BasicStroke.JOIN_ROUND);
    graph.setStroke(aLine2);

    //notch on numbers and grid lines
    //left to right, top to bottom notches
    int v2 = -5;
    int v5 = 0;
    while(i <= a1-1){

        p.drawLine(Da,0,Ea,y1);
        a = a + d;
        b = b + e;
        i = i + 1;
    }
    //notches
    while(i2 <= a1){
        p.setColor(Color.blue);//notch color
        p.drawString("x",v2+2,y+3);//xaxis
        p.drawString("x",x-4,v5+4);//yaxis
        v5 = v5 + e;
        v2 = v2 + d;
        i2 = i2 + 1;
    }


    }
  }
}




import java.awt.*;
import javax.swing.*;


}
}



 /*
  * this code is to accept a user input in order for him to
  * change the ranges of the xaxis and yaxis to his needs
  */

import javax.swing.Box;
import javax.swing.JButton;
import javax.swing.JTextField;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

class ControlsB extends JPanel{

    private static final long serialVersionUID = 1L;
    public static int xaxis1,xaxis2,yaxis3,yaxis4;

    //public int xaxis11,xaxis22,yaxis33,yaxis44;
    //public Object ControlsB;
    //private Graph graph;
    //public static Graphics p;
    public String s;

public ControlsB(Box box2) {

    JButton btn1 = new JButton("Resize");

    final Box 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

    //x-axis
    b1.add(new JLabel("x-axis "));
    b1.add(new JLabel("from"));

    final JTextField f1 = new JTextField("  0");

    f1.setMaximumSize(new Dimension(100,30));


 b.add(btn1);
}

protected Object Integer(int xaxis12) {
    return null;
}
}

现在这个程序的问题是；在 ControlsB 中，我有一种方法将控件放置在底部(在黄色框/图形下方)，现在这些控件应该接受 x 轴线上的图形范围(x -axis 仅目前，因为 y 轴的代码尚未准备好)。当用户按下“调整大小”按钮时，图表应该显示更改。

但是这并没有发生，并且按钮被无缘无故地按下......我不知道我出了什么问题。

在 ControlsB 文件中，我有一个 btn1 的 Action 监听器，即“调整大小”按钮，并且按下底部后立即它将文本字段输入(f1 和 f2)更改为整数并分配给 x 轴 1、x 轴 2 等...

现在，我使用以下行从这些变量(在操作监听器方法中找到)对类 Graph.java 进行引用:public static int xaxis11 = ControlsB.xaxis1;

任何人都可以告诉我这个问题的最佳解决方案是什么..??..

注意:所有这些文件都可以编译。但图表没有出现。

Answer 1

按照当前的编码方式，您分配的是 xaxis11、xaxis22、yaxis33 和 yaxis44 > 仅一次。当变量在 ControlsB 中发生更改时，它们不会动态更新。这意味着您只需在每次值更改时更新它们即可。为此，请向您的 Graph 类添加一个方法:

public static void updateGraph() {
    xaxis11 = ControlsB.xaxis1;
    xaxis22 = ControlsB.xaxis2;
    yaxis33 = ControlsB.yaxis3;
    yaxis44 = ControlsB.yaxis4;
}

然后，当用户更改 ControlsB 中的值时，调用 Graph.update()。确保发生这种情况时您也调用了 repaint。

另请注意，将所有这些内容设为静态并不是您唯一的选择。您还可以简单地将对象的引用作为另一个类的字段，在构造函数中设置它，并在必要时调用它的方法。由于这个问题，您的实现可能会遇到一些问题，因为将所有内容设为静态可能会影响您在对象上调用 repaint() 的能力，而您需要执行此操作才能更新它。

解决该问题的方法是将 repaint() 添加到我上面概述的 updateGraph 方法的底部。