在JPanel上绘制条形图并将其添加到JScrollPane上可以在Mac操作系统上工作，但在Windows操作系统上不行？[副本]

Question

我的代码的一个特点是，它显示了一个频率条形图，其中有给定的数据。在我的MacBook上，它工作的非常好，但是当我尝试在我的Razer刀片上使用它时，它并不像预期的那样工作。我提供了截图，所以你可以看到发生了什么，如果你可以给我一些关于这一点的见解。

Windows操作系统:https://gyazo.com/5107EED39D548687AD772A60E065055B

Mac操作系统:https://gyazo.com/6d32df9e08b9ce0c089dbe1b4d35af64

import javax.swing.*;
import java.awt.*;
import java.util.HashMap;
import java.util.Map;

public class Main {

    public static void main(String[] args){
        SwingUtilities.invokeLater(BarChartGUI::new);
    }

}

class BarChartGUI extends JFrame{

    public BarChartGUI(){

        Map<String, Integer> frequencyTableData = getFrequencyTableData();
        BarChart barChart = new BarChart(frequencyTableData);
        JScrollPane chartScrollPane = new JScrollPane(barChart);
        chartScrollPane.setPreferredSize(new Dimension(1000, 500));
        add(chartScrollPane);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        pack();
        setLocationRelativeTo(null);
        setVisible(true);
    }

    private Map<String, Integer> getFrequencyTableData(){
        Map<String, Integer> frequencyTableData = new HashMap<>();
        for (int i = 0; i < 2000; i++){
            frequencyTableData.put(String.valueOf(i), i);
        }
        return frequencyTableData;
    }
}

class BarChart extends JPanel {

    // Space to draw Chart Information
    public static final int TOP_BUFFER = 30;
    public static final int AXIS_OFFSET = 20;

    // Hashmap datatype holds the frequency of the String within the columnValues
    private final Map<String, Integer> data;

    // Stores dimension values
    private int chartWidth;
    private int chartHeight;
    private int chartY;

    public BarChart(Map<String, Integer> frequencyTableData){
        super();
        data = frequencyTableData;

        setBackground(Color.white);

        // Makes the Panel larger if the bar chart is not able to be fully displayed
        if ((chartWidth / frequencyTableData.size() < 5)) {
            setPreferredSize(new Dimension(5*frequencyTableData.size() + 50, getHeight()));
        }

    }

    public void paintComponent(Graphics g) {
        Graphics2D g2 = (Graphics2D) g;

        computeSize();
        drawBars(g2);
    }

    // Retrieves the size of panel
    private void computeSize() {
        // Gets the chart's area size
        chartWidth = this.getWidth() - 2*AXIS_OFFSET;
        chartHeight = this.getHeight() - 2*AXIS_OFFSET - TOP_BUFFER;

        // Get's the chart's coords for the origin
        chartY = this.getHeight() - AXIS_OFFSET;
    }

    // Draws the Bar Chart depending on the values and its frequency stored within data
    public void drawBars(Graphics2D g2) {
        int numberOfBars = data.size();
        double maxHeight = 0;

        // Finds the height of the highest bar
        for (Integer freq : data.values()) {
            if (maxHeight < freq)
                maxHeight = freq;
        }

        // Calculates width of bar
        int barWidth = chartWidth / numberOfBars;
        if ((chartWidth / numberOfBars) < 5){
            barWidth = 5;
        }

        int value;
        int barHeight;
        int xLeftCord;
        int yTopLeftCord;
        int counter = 0;
        g2.setColor(Color.black);

        // Draws the bar for every key in the hashmap
        for (String bar : data.keySet()) {
            value = data.get(bar);

            double barHeightDecimal = (value/maxHeight)* chartHeight;
            barHeight = (int) barHeightDecimal;

            xLeftCord = AXIS_OFFSET + counter * barWidth;
            yTopLeftCord = chartY - barHeight;
            Rectangle rec = new Rectangle(xLeftCord, yTopLeftCord, barWidth, barHeight);

            g2.draw(rec);

            counter++;
        }
    }



}

Answer 1

这个：

public void paintComponent(Graphics g) {
    Graphics2D g2 = (Graphics2D) g;

    computeSize();
    drawBars(g2);
}

缺少对Super的方法的调用：

public void paintComponent(Graphics g) {
    super.paintComponent(g);
    Graphics2D g2 = (Graphics2D) g;

    computeSize();
    drawBars(g2);
}

没有这一点，JPanel就无法进行内务绘画或清除脏像素