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java - 如何在 JFrame 上显示 Graphics2D 对象

问题描述

这是我第一次尝试构建 GUI，但我陷入了僵局，我似乎无法找到解决方案。目前我已经设置了部分 GUI，但我想插入我在另一个类上创建的图形，但是，我不确定如何将它与我当前的 JFrame 链接。我可以让它作为一个单独的实体工作，但不能一起工作。

主显示类：

public static void main(String args[]) {
    /* Set the Nimbus look and feel */
    //<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
    /* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
     * For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html 
     */
    try {
        for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
            if ("Nimbus".equals(info.getName())) {
                javax.swing.UIManager.setLookAndFeel(info.getClassName());
                break;
            }
        }
    } catch (ClassNotFoundException ex) {
        java.util.logging.Logger.getLogger(MainDisplay.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    } catch (InstantiationException ex) {
        java.util.logging.Logger.getLogger(MainDisplay.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    } catch (IllegalAccessException ex) {
        java.util.logging.Logger.getLogger(MainDisplay.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    } catch (javax.swing.UnsupportedLookAndFeelException ex) {
        java.util.logging.Logger.getLogger(MainDisplay.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    }
    //</editor-fold>
    //</editor-fold>

    /* Create and display the form */
    java.awt.EventQueue.invokeLater(new Runnable() {
        public void run() {
            new MainDisplay().setVisible(true);
        }

    });
     float LvBTC;
    float LvLTC;
    float LvETH;

    float[] HBTC;
    float[] HLTC;
    float[] HETH;

    float CurETH;
    float CurBTC;
    float CurLTC;

    WebScraper WS1 = new WebScraper();
    LvBTC = WS1.LvScrapeBTC();
    LvLTC = WS1.LvScrapeLTC();
    LvETH = WS1.LvScrapeETH();

    HBTC = WS1.HScrapeBTC();
    HLTC = WS1.HScrapeLTC();
    HETH = WS1.HScrapeETH(); 

    System.out.println("Bitcoin's Current Price is: $"+LvBTC);
    System.out.println("Litecoin's Current Price is: $"+LvLTC);
    System.out.println("Ethereum's Current Price is: $"+LvETH);
    Graph G1 = new Graph();
    G1.CurrentValues(HBTC);

    for (int i = 0; 5 > i;) {
        System.out.println("Day " + (i + 1) + ": $" + G1.CurValues[i]);
        i++;
    }

   System.out.println("Index of largest value: " + G1.IndexLarge(G1.CurValues));
    System.out.println("Index of smallest value: " + G1.IndexSmall(G1.CurValues));

    Graph Graphing = new Graph();



}

图表类：

package comsci_ia;

import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Point;
import java.util.ArrayList;
import java.util.Arrays;

import javax.swing.JFrame;

public class Graph extends JFrame {

int IndexL;
int IndexS;
int DistanceDay1;
int DistanceDay2;
int DistanceDay3;
int DistanceDay4;
int DistanceDay5;
float[] CurValues = new float[5];

ArrayList<Point> points = new ArrayList<>();

public float[] CurrentValues(float[] array) {
    DatabaseBrowser DB1 = new DatabaseBrowser();
    WebScraper WS1 = new WebScraper();

    float[] HBTC = WS1.HScrapeBTC();
    float[] HETH = WS1.HScrapeETH();
    float[] HLTC = WS1.HScrapeLTC();

    float CurHold = 0;

    boolean BTCCheck = false;
    BTCCheck = Arrays.equals(HBTC, array);

    boolean LTCCheck = false;
    LTCCheck = Arrays.equals(HLTC, array);

    boolean ETHCheck = false;
    ETHCheck = Arrays.equals(HETH, array);

    if (BTCCheck == true) {
        CurHold = DB1.RetriveBTC();
    }

    if (LTCCheck == true) {
        CurHold = DB1.RetriveLTC();
    }

    if (ETHCheck == true) {
        CurHold = DB1.RetriveETH();
    }

    float pick;

    for (int i = 0; 5 > i;) {
        for (int z = 0; z < array.length; z++) {
            pick = array[z];
            pick = pick * CurHold;
            CurValues[i] = pick;
            i++;
        }

    }
    return CurValues;
}

public int IndexLarge(float[] array) {
    float temp = 0;
    for (int i = 0; 5 > i;) { //Cycles through ArrayList and replaces temp with the Largest value
        if (array[i] > temp) {
            temp = array[i];
        }
        i++;
    }
    int IndexCheck = 0; //Searches and records the index of "temp" value (Largest value in array)
    for (IndexCheck = 0; 5 > IndexCheck;) {
        if (array[IndexCheck] == temp) {
            break;
        }
        IndexCheck++;
    }
    IndexL = IndexCheck;
    return IndexL;
}

public int IndexSmall(float[] array) {
    float temp = 1000000;
    for (int i = 0; 5 > i;) { //Cycles through ArrayList and replaces temp with the smallest value
        if (array[i] < temp) {
            temp = array[i];
        }
        i++;
    }
    int IndexCheck = 0; //Searches and records the index of "temp" value (smallest value in array)
    for (IndexCheck = 0; 5 > IndexCheck;) {
        if (array[IndexCheck] == temp) {
            break;
        }
        IndexCheck++;
    }
    IndexS = IndexCheck;
    return IndexS;
}

public void Plotter(float[] array) { 
  /*  int DayRefL = IndexL + 1;
    int DayRefS = IndexS + 1; */
    float ValRange;
    float ValPx;

    points = null;

    ValRange = array[IndexL] - array[IndexS];
    ValPx = (300f/ ValRange); //Number is the pixel distance between highest and lowest values
    DistanceDay1 = (int) ((int) 50 + ((array[IndexL] - array[0]) * ValPx));
    DistanceDay2 = (int) ((int) 50 + ((array[IndexL] - array[1]) * ValPx));
    DistanceDay3 = (int) ((int) 50 + ((array[IndexL] - array[2]) * ValPx));
    DistanceDay4 = (int) ((int) 50 + ((array[IndexL] - array[3]) * ValPx));
    DistanceDay5 = (int) ((int) 50 + ((array[IndexL] - array[4]) * ValPx));

}
public void paintComponent(Graphics g) {

    Graphics2D g2 = (Graphics2D) g;

    int DotSize = 10;

    int width = g2.getFontMetrics().stringWidth("Today");
    int middle = width / 2;

    g2.setColor(Color.BLACK);
    /* g2.drawLine(10, 10, 10, 410); //Frame Boundaries
    g2.drawLine(410, 10, 10, 10); //Frame Boundaries
    g2.drawLine(410, 10, 410, 410); //Frame Boundaries
    g2.drawLine(410, 410, 10, 410); //Frame Boundaries */

    //Axis
    g2.drawLine(30, 30, 30, 370);
    g2.drawLine(370, 370, 30, 370);

    //Points & Connections
    PlotPoints(g2, 98, DistanceDay1, DotSize);
    g2.drawLine(98, DistanceDay1, 166, DistanceDay2);
    PlotPoints(g2, 166, DistanceDay2, DotSize);
    g2.drawLine(166, DistanceDay2, 234, DistanceDay3);
    PlotPoints(g2, 234, DistanceDay3, DotSize);
    g2.drawLine(234, DistanceDay3, 302, DistanceDay4);
    PlotPoints(g2, 302, DistanceDay4, DotSize);
    g2.drawLine(302, DistanceDay4, 370, DistanceDay5);
    PlotPoints(g2, 370, DistanceDay5, DotSize);

    //Labels
    g2.drawString("Today", 370 - middle, 390);
  /*  g2.drawString("Test", 98 - middle, 40);
    g2.drawString("Test", 146, 25); */

}

private void PlotPoints(Graphics2D g, int x, int y, int r) {
    x = x - (r / 2);
    y = y - (r / 2);
    g.fillOval(x, y, r, r);
}

}

如果我将 Graph 类作为单独的实体运行，则会导致：Graph pop-up

这是图形代码的单独版本，其中将弹出一个框架来显示图形：

package graphing;

import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;

import javax.swing.JFrame;
import javax.swing.JPanel;

public class Graphing extends JPanel {

@Override
public void paintComponent(Graphics g) {

    Graphics2D g2 = (Graphics2D) g;

    int DotSize = 10;

    int width = g2.getFontMetrics().stringWidth("Test");
    int middle = width / 2;

    g2.setColor(Color.BLACK);
    g2.drawLine(10, 10, 10, 390); //Frame Boundaries
    g2.drawLine(390, 10, 10, 10); //Frame Boundaries
    g2.drawLine(390, 10, 390, 390); //Frame Boundaries
    g2.drawLine(390, 390, 10, 390); //Frame Boundaries

    //Axis
    g2.drawLine(30, 30, 30, 370);
    g2.drawLine(370, 370, 30, 370);

    //Points & Connections
    PlotPoints(g2, 98, 55, DotSize);
    g2.drawLine(98, 55, 166, 40);
    PlotPoints(g2, 166, 40, DotSize);
    g2.drawLine(166, 40, 234, 100);
    PlotPoints(g2, 234, 100, DotSize);
    g2.drawLine(234, 100, 302, 332);
    PlotPoints(g2, 302, 332, DotSize);
    g2.drawLine(302, 332, 370, 40);
    PlotPoints(g2, 370, 40, DotSize);

    //Labels
    g2.drawString("Test", 98 - middle, 40);
    g2.drawString("Test", 146, 25);

}

private void PlotPoints(Graphics2D g, int x, int y, int r) {
    x = x - (r / 2);
    y = y - (r / 2);
    g.fillOval(x, y, r, r);
}

public static void main(String[] args) {
    JFrame frame = new JFrame();
    frame.setSize(420, 420);
    frame.setLocationRelativeTo(null);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    Graphing app = new Graphing();

    frame.setContentPane(app);

    frame.setVisible(true);
    frame.invalidate();
}

}

标签： javauser-interfacenetbeansgraphics2dgraphing

解决方案

所以，我的直接问题是，你从 扩展JFrame，这不好，因为这会将 UI 锁定在一个用例中（它不容易重用）

我的第二个问题是，您创建了一个名为paintComponentin的方法JFrame，但由于JFrame不使用这种绘画风格，因此它永远不会被调用

所以，我要做的第一件事就是改变Graph，所以它从JPanel…

public class Graph extends JPanel {
    //...

然后我会更新你的paintComponent，以便它正确支持绘画过程......

@Overrride
protected void paintComponent(Graphics g) {
    super.paintComponent(g);
    Graphics2D g2 = (Graphics2D) g;
    //...

现在，下一个问题是，您将需要提供一些尺寸提示，以便您添加它的容器的布局管理器对如何最好地布局组件有一些想法......

@Override
public Dimension getPreferredSize() {
    // I've not been through your code in detail
    // so I've not calculated what the actual
    // preferred size might be and this is just an
    // example you'll have to update
    return new Dimension(200, 200);
}

现在，您可以创建一个实例Graph并将其添加到您想要的任何容器中

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