Java窗口运行不显示内容，放大一下才显示内容。

Question

求助：Java窗口运行不显示内容，放大一下才显示内容。大佬们帮忙看看这是我的代码问题还是其他啥问题？

import java.awt.*;
import javax.swing.*;
public class SchoolWork extends JFrame {
    public static void main(String args[]) {
        JFrame frame = new JFrame("常用组件") ;
        JCheckBox checkBox1,checkBox2,checkBox3,checkBox4;
        JRadioButton radioM,radioF;
        JComboBox<String>comBox;
        JTextField text;
        JLabel textLab1,textLab2,textLab3,textLab4,textLab5,textLab6;
        JButton but;
        ButtonGroup group;
        JTextArea jText;

        frame.setVisible(true);
        frame.setBounds(100,100,380,260);
        frame.setLocationRelativeTo(null);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setLayout(new FlowLayout(FlowLayout.CENTER,30,20));

        JPanel panel = new JPanel();
        frame.setContentPane(panel);


        text = new JTextField(15) ;
        textLab1 = new JLabel("文本框：") ;
        frame.setLayout(new FlowLayout());
        panel.add(textLab1);
        panel.add(text);
        textLab2 = new JLabel("按钮：") ;
        panel.add(textLab2);
        but = new JButton("按钮");
        Font fnt = new Font("Serief",Font.BOLD,12);
        but.setFont(fnt) ;
        panel.add(but);

        textLab3 = new JLabel("选择框：");
        panel.add(textLab3);
        checkBox1 = new JCheckBox("喜欢音乐");
        checkBox2 = new JCheckBox("喜欢足球");
        checkBox3 = new JCheckBox("喜欢游泳");
        panel.add(checkBox1);
        panel.add(checkBox2);
        panel.add(checkBox3);

        textLab4 = new JLabel("单选按钮：");
        panel.add(textLab4);

        radioM = new JRadioButton("男");
        radioF = new JRadioButton("女");
        group = new ButtonGroup();
        group.add(radioF);
        group.add(radioM);
        panel.add(radioF);
        panel.add(radioM);

        textLab5 = new JLabel("下拉列表：");
        panel.add(textLab5);
        comBox = new JComboBox<String>(); 
        comBox.addItem("音乐天地");
        comBox.addItem("武术天地");
        panel.add(comBox);

        textLab6 = new JLabel("文本区：");
        panel.add(textLab6);
        jText = new JTextArea(5,20);
        panel.add(jText);
    }
}

Answer 1

代码最后调用下
frame.repaint();
frame.setVisible(true);