Frame设置颜色无效

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

public class TankGame {
    JFrame jFrame = null;

    public TankGame() {
        this.jFrame = new JFrame("坦克大战");
        this.jFrame.setVisible(true);
        this.jFrame.setSize(1000,750);
        this.jFrame.setDefaultCloseOperation(jFrame.EXIT_ON_CLOSE);
    }

    public static void main(String[] args) {
        TankGame tankGame = new TankGame();
        MyPanel myPanel = new MyPanel(tankGame.jFrame);
    }
}
class MyPanel extends JPanel{
    JPanel jPanel = null;

    public MyPanel(JFrame jFrame) {
        this.jPanel = new JPanel();
        this.jPanel.setBackground(new Color(105,105,105));//深灰不是默认颜色
        jFrame.add(this.jPanel);
    }
}

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为什么this.jPanel.setBackground(new Color(105,105,105));没有效果呢？

我运行你的代码，好像没问题，是这个颜色吗？

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