java–在JFrame中将JPanel从另一个类添加到JPanel

我无法从主类中获取我的JFrame来显示另一个类的JPanel.一切都编译没有错误.

JFrameTest.java：

package jframetest;
import java.awt.FlowLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class JFrameTest extends JFrame {
public JFrameTest() {
FlowLayout mainLayout = new FlowLayout();
setSize(320, 480);
setResizable(false);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setLayout(mainLayout);
JPanel panelMain = new JPanel(mainLayout);
JButton testButton = new JButton("Test12");
panelMain.add(testButton);
JPanelOne panel = new JPanelOne();
panelMain.add(panel);
panel.setVisible(true);
add(panelMain);
}
public static void main(String[] arguments) {
JFrameTest frame = new JFrameTest();
frame.setVisible(true);
}
}


JPanelOne.java：

package jframetest;
import java.awt.FlowLayout;
import javax.swing.JButton;
import javax.swing.JPanel;
public class JPanelOne extends JPanel {
public JPanelOne() {
FlowLayout layoutPanel = new FlowLayout();
JPanel panel = new JPanel(layoutPanel);
JButton button = new JButton("test");
panel.add(button);
panel.setVisible(true);
}
}


将不同的JPanel保留在自己的类中是一种好习惯吗？ (示例：希望JFrame包含几个相同大小的JPanel,将通过将setVisible()设置为true / false来切换)

编辑

谢谢你的所有答案.指出.现在回到我的问题：

现在我知道如何添加在其他类中创建的单个GUI元素,我想知道是否可以在其中一个类中组织具有布局管理器的元素(可能在除JPanel之外的其他容器中),因此我可以将它们添加为组织布局(这就是为什么我要求在其他类中创建整个JPanel).如图所示：

这个例子的JPanel(第二类)代码是：

package jframetest;
import java.awt.*;
import javax.swing.JButton;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JSeparator;
import net.miginfocom.swing.MigLayout;
public class JPanelOne extends JPanel {
private JPanel panelSettingsMain;
private JLabel labelChooseLanguage, labelWordsCollection;
private JButton buttonSelectLanguage, buttonSelectCollection,
buttonStatistics, buttonPrintingOptions, buttonAddNewWordCollection,
buttonInterfaceCustomization;
private JSeparator separatorSettingsOne, separatorSettingsTwo,
separatorSettingsThree, separatorSettingsFour,
separatorSettingsFive;
private Color greenRegular, separatorGreenLight, separatorGreenDark;
public JPanelOne() {
// creating settings main panel
// setting up layout managers
MigLayout layoutSettingsMain = new MigLayout("insets 3 0 0 0");
// setting up colors
greenRegular = new Color(30, 165, 145);
separatorGreenLight = new Color(190, 240, 220);
separatorGreenDark = new Color(130, 205, 180);
panelSettingsMain = new JPanel(layoutSettingsMain);
panelSettingsMain.setBackground(Color.WHITE);
// setting up choose language label
labelChooseLanguage = new JLabel("Choose language:");
panelSettingsMain.add(labelChooseLanguage, "gapleft 10, gaptop 15, width 200");
// setting up select language button
buttOnSelectLanguage= new JButton("language");
buttonSelectLanguage.setForeground(greenRegular);
buttonSelectLanguage.setFocusPainted(false);
buttonSelectLanguage.setBorder(null);
buttonSelectLanguage.setContentAreaFilled(false);
buttonSelectLanguage.setCursor(new java.awt.Cursor( java.awt.Cursor.HAND_CURSOR));
panelSettingsMain.add(buttonSelectLanguage, "gapbottom 15px, wrap");
// setting up light separator
separatorSettingsOne= new JSeparator();
separatorSettingsOne.setForeground(separatorGreenLight);
panelSettingsMain.add(separatorSettingsOne, "span 2, width 320, gapbottom 15, wrap");
// setting up words collection label
labelWordsCollection = new JLabel("Words collection:");
panelSettingsMain.add(labelWordsCollection, "gapleft 10");
// setting up selectcollection button
buttOnSelectCollection= new JButton("collection");
buttonSelectCollection.setForeground(greenRegular);
buttonSelectCollection.setFocusPainted(false);
buttonSelectCollection.setBorder(null);
buttonSelectCollection.setContentAreaFilled(false);
buttonSelectCollection.setCursor(new java.awt.Cursor( java.awt.Cursor.HAND_CURSOR));
panelSettingsMain.add(buttonSelectCollection, "gapbottom 15px, wrap");
// setting up dark separator
separatorSettingsTwo = new JSeparator();
separatorSettingsTwo.setForeground(separatorGreenDark);
panelSettingsMain.add(separatorSettingsTwo, "span 2, width 320, gapbottom 15px, wrap");
// setting up show statistics button
buttOnStatistics= new JButton("Show statistics");
buttonStatistics.setForeground(greenRegular);
buttonStatistics.setFocusPainted(false);
buttonStatistics.setBorder(null);
buttonStatistics.setContentAreaFilled(false);
buttonStatistics.setCursor(new java.awt.Cursor( java.awt.Cursor.HAND_CURSOR));
panelSettingsMain.add(buttonStatistics, "gapleft 10, gapbottom 15px, , wrap");
// setting up dark separator
separatorSettingsThree = new JSeparator();
separatorSettingsThree.setForeground(separatorGreenDark);
panelSettingsMain.add(separatorSettingsThree, "span 2, width 320, gapbottom 15px, wrap");
// setting up printing options button
buttOnPrintingOptions= new JButton("Printing options");
buttonPrintingOptions.setForeground(greenRegular);
buttonPrintingOptions.setFocusPainted(false);
buttonPrintingOptions.setBorder(null);
buttonPrintingOptions.setContentAreaFilled(false);
buttonPrintingOptions.setCursor(new java.awt.Cursor( java.awt.Cursor.HAND_CURSOR));
panelSettingsMain.add(buttonPrintingOptions, "gapleft 10, gapbottom 15px, wrap");
// setting up dark separator
separatorSettingsFour = new JSeparator();
separatorSettingsFour.setForeground(separatorGreenDark);
panelSettingsMain.add(separatorSettingsFour, "span 2, width 320, gapbottom 15px, wrap");
// setting up add new word collection button
buttOnAddNewWordCollection= new JButton("Add new word collection");
buttonAddNewWordCollection.setForeground(greenRegular);
buttonAddNewWordCollection.setFocusPainted(false);
buttonAddNewWordCollection.setBorder(null);
buttonAddNewWordCollection.setContentAreaFilled(false);
buttonAddNewWordCollection.setCursor(new java.awt.Cursor( java.awt.Cursor.HAND_CURSOR));
panelSettingsMain.add(buttonAddNewWordCollection, "gapleft 10, gapbottom 15px, , wrap");
// setting up dark separator
separatorSettingsFive = new JSeparator();
separatorSettingsFive.setForeground(separatorGreenDark);
panelSettingsMain.add(separatorSettingsFive, "span 2, width 320, gapbottom 10px, wrap");
// setting up interface customization button
buttOnInterfaceCustomization= new JButton( "Interface customization");
buttonInterfaceCustomization.setForeground(greenRegular);
buttonInterfaceCustomization.setFocusPainted(false);
buttonInterfaceCustomization.setBorder(null);
buttonInterfaceCustomization.setContentAreaFilled(false);
buttonInterfaceCustomization.setCursor(new java.awt.Cursor( java.awt.Cursor.HAND_CURSOR));
panelSettingsMain.add(buttonInterfaceCustomization, "gapleft 10, gapbottom 15px, wrap");
}
}


我正在考虑通过将JPanels(示例中的那些)设置为可见或不可见来浏览程序GUI.

>这是好方法吗？
>我应该将我的GUI分成几个类,还是我应该将所有内容保存在一个类中？我问,因为现在代码中只有一半的GUI大约有400行(并且它不能做任何事情而不仅仅是“看”这一点).正如我之前所说 – 我是初学者,也是我迄今为止写过的最长的应用程序之一(我确信它不会那么长！).

编辑

也许我正在过度思考它,所以最终是否可以拥有大的GUI类并通过将它们设置为可见来控制不同GUI区域的可见性？

编辑

我查看了Oracle的CardLayout教程,看起来它对我的任务有好处(不包括从外部类创建JPanel,但没关系).我一开始误解了它,只是在标签窗格(我不希望在我的项目中实现)中考虑CardLayout.

解决方法:

首先回答你的问题,你需要在你的JFrameTest构造函数中添加一个面板实例到这样的东西：

add(new JPanelOne());


您还需要将按钮直接添加到JPanelOne本身：

public class JPanelOne extends JPanel {
public JPanelOne() {
JButton button = new JButton("test");
add(button);
}
}


其次,我认为这些代码行存在问题：

FlowLayout mainLayout = new FlowLayout();
// snip...
setLayout(mainLayout);
JPanel panelMain = new JPanel(mainLayout);


每个容器都应该有自己的布局管理器实例.否则你的GUI会做一些奇怪的事情：

setLayout(new FlowLayout());
JPanel panelMain = new JPanel(mainLayout);