Java标签消失

Question

我想制定一个简单的议程，但不知何故，当我运行编译器时，它不会加载标签的文本，有时会加载。我该如何解决？

示例:(无法显示图片)

1. 13:00pm(这是总是出现的)类(class) A
2. 下午 13:30 类(class) b

有时它会这样做:

1. 13:00pm(总是出现)(然后什么也没有)
2. 下午 13:30

(请保持简单，因为我是初学者，来自荷兰)。

代码:(我是初学者，所以不要看那些复制粘贴的东西)

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

class P{
    public static void main(String [] args){
        JFrame frame = new JFrame(" Agenda 10/13/2014");
        frame.setDefaultCloseOperation(frame.EXIT_ON_CLOSE);
        frame.setSize(620,620);
        frame.setResizable(false);
        frame.setVisible(true);

    JLabel labeltime1 = new JLabel("1:00 - 1:30pm: ");
    JLabel labeltime2 = new JLabel("1:30 - 2:00pm: ");
    JLabel labeltime3 = new JLabel("2:00 - 2:30pm: ");
    JLabel labeltime4 = new JLabel("2:30 - 3:00pm: ");
    JLabel labeltime5 = new JLabel("3:00 - 3:30pm: ");

    labeltime1.setForeground(Color.red);
    labeltime2.setForeground(Color.red);
    labeltime3.setForeground(Color.red);
    labeltime4.setForeground(Color.red);
    labeltime5.setForeground(Color.red);

    JLabel space1 = new JLabel("\n");
    JLabel space2 = new JLabel("\n");
    JLabel space3 = new JLabel("\n");
    JLabel space4 = new JLabel("\n");
    JLabel space5 = new JLabel("\n");

    JPanel timeP = new JPanel();
    timeP.setBackground(Color.black);
    timeP.setLayout(new BoxLayout(timeP, BoxLayout.Y_AXIS));

    timeP.add(space5);
    timeP.add(labeltime1);
    timeP.add(space1);
    timeP.add(labeltime2);
    timeP.add(space2);
    timeP.add(labeltime3);
    timeP.add(space3);
    timeP.add(labeltime4);
    timeP.add(space4);
    timeP.add(labeltime5);

    frame.getContentPane().add(BorderLayout.WEST, timeP);

    JPanel courses = new JPanel();
    courses.setLayout(new BoxLayout(courses, BoxLayout.Y_AXIS));
    courses.setBackground(Color.black);
    frame.getContentPane().add(BorderLayout.CENTER,courses);

    //Enter your course
    JLabel course1 = new JLabel(" Course A");
    JLabel course2 = new JLabel(" Course B");
    JLabel course3 = new JLabel(" Course C");
    JLabel course4 = new JLabel(" Course D");
    JLabel course5 = new JLabel(" Course E");

    course1.setForeground(Color.yellow);
    course2.setForeground(Color.yellow);
    course3.setForeground(Color.yellow);
    course4.setForeground(Color.yellow);
    course5.setForeground(Color.yellow);

    JLabel space6 = new JLabel("\n");
    JLabel space7 = new JLabel("\n");
    JLabel space8 = new JLabel("\n");
    JLabel space9 = new JLabel("\n");
    JLabel space10 = new JLabel("\n");

    courses.add(space6);
    courses.add(course1);
    courses.add(space7);
    courses.add(course2);
    courses.add(space8);
    courses.add(course3);
    courses.add(space9);
    courses.add(course4);
    courses.add(space10);
    courses.add(course5);


}

}

Answer 1

将 frame.setVisible(true); 移动到最后一行将解决您的问题。您需要在添加组件后调用 setvisible 。或者您可以调用 repaint(),revalidate();

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

class P{
    public static void main(String [] args){
        JFrame frame = new JFrame(" Agenda 10/13/2014");
        frame.setDefaultCloseOperation(frame.EXIT_ON_CLOSE);
        frame.setSize(620,620);
        frame.setResizable(false);
        //frame.setVisible(true);//don't call this method here

    JLabel labeltime1 = new JLabel("1:00 - 1:30pm: ");
    JLabel labeltime2 = new JLabel("1:30 - 2:00pm: ");
    JLabel labeltime3 = new JLabel("2:00 - 2:30pm: ");
    JLabel labeltime4 = new JLabel("2:30 - 3:00pm: ");
    JLabel labeltime5 = new JLabel("3:00 - 3:30pm: ");

    labeltime1.setForeground(Color.red);
    labeltime2.setForeground(Color.red);
    labeltime3.setForeground(Color.red);
    labeltime4.setForeground(Color.red);
    labeltime5.setForeground(Color.red);

    JLabel space1 = new JLabel("\n");
    JLabel space2 = new JLabel("\n");
    JLabel space3 = new JLabel("\n");
    JLabel space4 = new JLabel("\n");
    JLabel space5 = new JLabel("\n");

    JPanel timeP = new JPanel();
    timeP.setBackground(Color.black);
    timeP.setLayout(new BoxLayout(timeP, BoxLayout.Y_AXIS));

    timeP.add(space5);
    timeP.add(labeltime1);
    timeP.add(space1);
    timeP.add(labeltime2);
    timeP.add(space2);
    timeP.add(labeltime3);
    timeP.add(space3);
    timeP.add(labeltime4);
    timeP.add(space4);
    timeP.add(labeltime5);

    frame.getContentPane().add(BorderLayout.WEST, timeP);

    JPanel courses = new JPanel();
    courses.setLayout(new BoxLayout(courses, BoxLayout.Y_AXIS));
    courses.setBackground(Color.black);
    frame.getContentPane().add(BorderLayout.CENTER,courses);

    //Enter your course
    JLabel course1 = new JLabel(" Course A");
    JLabel course2 = new JLabel(" Course B");
    JLabel course3 = new JLabel(" Course C");
    JLabel course4 = new JLabel(" Course D");
    JLabel course5 = new JLabel(" Course E");

    course1.setForeground(Color.yellow);
    course2.setForeground(Color.yellow);
    course3.setForeground(Color.yellow);
    course4.setForeground(Color.yellow);
    course5.setForeground(Color.yellow);

    JLabel space6 = new JLabel("\n");
    JLabel space7 = new JLabel("\n");
    JLabel space8 = new JLabel("\n");
    JLabel space9 = new JLabel("\n");
    JLabel space10 = new JLabel("\n");

    courses.add(space6);
    courses.add(course1);
    courses.add(space7);
    courses.add(course2);
    courses.add(space8);
    courses.add(course3);
    courses.add(space9);
    courses.add(course4);
    courses.add(space10);
    courses.add(course5);
    frame.setVisible(true);//call here

}

}