Java（GUI）中的消息对话框-yiteyi-C++库

消息对话框向用户提供信息。消息对话框是使用JOptionPane创建的。showMessageDialog（）方法。

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我们称之为 静态showMessageDialog（） 方法创建消息对话框。我们提供对话框的父级、消息文本、标题和消息类型。消息类型是以下常量之一：

错误消息
警告信息
问题(留言)
信息和信息

使用的方法：

setLayout（…）： 方法帮助我们设置容器的布局，通常是一个JPanel，也就是说FlowLayout、BorderLayout、GridLayout、null布局，或者我们想要添加到容器上的任何布局。
挫折（…）： 方法用于设置JButton等组件的位置和大小，并且只有在JFrame中使用null布局时才有用。
setVisible（…）： 方法用于设置JFrame的可见性状态。
1. setVisible（true）将设置JFrame对用户可见。
2. setVisible（false）将设置JFrame对用户不可见。
getSource（）： 事件对象包含对生成事件的组件的引用。要从事件对象中提取该引用，我们使用getSource（）方法。
添加（）： 它用于将JButton等组件添加到JFrame的容器中。

下面是上述显示消息对话框方法的实现：

JAVA

                         // Java program to show ERROR_MESSAGE dialog                       
                         // in Java. Importing different Package.                       
                         import                                     java.awt.*;                       
                         import                                     java.awt.event.*;                       
                         import                                     javax.swing.*;                       
           
                         class                                     Demo                                     extends                                     JFrame                                     implements                                     ActionListener                       
                         {                       
                                                 // Declaration of object of JButton class.                       
                                                 JButton b1;                       
                                   
                                                 // Constructor of Demo class                       
                                                 Demo()                       
                                                 {                       
                                                 // Setting layout as null of JFrame.                       
                                                 this                                     .setLayout(                                     null                                     );                       
                                   
                                                 // Initialization of object of "JButton" class.                       
                                                 b1 =                                     new                                     JButton(                                     "Button 1"                                     );                       
                                   
                                                 // Setting Bounds of a JButton.                       
                                                 b1.setBounds(                                     130                                     ,                                     05                                     ,                                     100                                     ,                                     50                                     );                       
                                   
                                                 //"this" keyword in java refers to current object.                       
                                                 // Adding JButton on JFrame.                       
                                                 this                                     .add(b1);                       
                                   
                                                 // Adding Listener toJButton.                       
                                                 b1.addActionListener(                                     this                                     );                       
                                                 }                       
           
                                                 // Override Method                       
                                                 public                                     void                                     actionPerformed(ActionEvent evt)                       
                                                 {                       
                                                 if                                     (evt.getSource() == b1)                       
                                                 {                       
                                                 // Code To popup an ERROR_MESSAGE Dialog.                       
                                                 JOptionPane.showMessageDialog(                                     this                                     ,                                     "Enter a valid Number"                                     ,                       
                                                 "ERROR"                                     , JOptionPane.ERROR_MESSAGE);                       
                                                 }                       
                                                 }                       
                         }                       
           
                         class                                     MessageDialogs1 {                       
                                   
                                                 // Driver code                       
                                                 public                                     static                                     void                                     main(String args[])                       
                                                 {                       
                                                 // Creating Object of demo class.                       
                                                 Demo f =                                     new                                     Demo();                       
                                   
                                                 // Setting Bounds of a Frame.                       
                                                 f.setBounds(                                     200                                     ,                                     200                                     ,                                     400                                     ,                                     300                                     );                       
                                   
                                                 // Setting Resizable status of frame as false                       
                                                 f.setResizable(                                     false                                     );                       
                                   
                                                 // Setting Visible status of frame as true.                       
                                                 f.setVisible(                                     true                                     );                       
                                                 }                       
                         }                       

输出：

图片[1]-Java（GUI）中的消息对话框-yiteyi-C++库

JAVA

                         // Java program to show WARNING_MESSAGE dialog                       
                         // in Java. Importing different Package.                       
                         import                                     java.awt.*;                       
                         import                                     java.awt.event.*;                       
                         import                                     javax.swing.*;                       
           
                         class                                     Demo                                     extends                                     JFrame                                     implements                                     ActionListener                       
                         {                       
                                                 // Declaration of object of JButton class.                       
                                                 JButton b1;                       
                                   
                                                 // Constructor of Demo class                       
                                                 Demo()                       
                                                 {                       
                                                 // Setting layout as null of JFrame.                       
                                                 this                                     .setLayout(                                     null                                     );                       
                                   
                                                 // Initialization of object of "JButton" class.                       
                                                 b1 =                                     new                                     JButton(                                     "Button 2"                                     );                       
                                   
                                                 // Setting Bounds of a JButton.                       
                                                 b1.setBounds(                                     130                                     ,                                     05                                     ,                                     100                                     ,                                     50                                     );                       
                                   
                                                 //"this" keyword in java refers to current object.                       
                                                 // Adding JButton on JFrame.                       
                                                 this                                     .add(b1);                       
                                   
                                                 // Adding Listener toJButton.                       
                                                 b1.addActionListener(                                     this                                     );                       
                                                 }                       
           
                                                 // Override Method                       
                                                 public                                     void                                     actionPerformed(ActionEvent evt)                       
                                                 {                       
                                                 if                                     (evt.getSource() == b1) {                       
                                   
                                                 // Code To popup an WARNING_MESSAGE Dialog.                       
                                                 JOptionPane.showMessageDialog(                                     this                                     ,                                     "Enter a valid String"                                     ,                       
                                                 "WARNING"                                     , JOptionPane.WARNING_MESSAGE);                       
                                                 }                       
                                                 }                       
                         }                       
           
                         class                                     MessageDialogs2 {                       
                                   
                                                 // Driver code                       
                                                 public                                     static                                     void                                     main(String args[])                       
                                                 {                       
                                                 // Creating Object of demo class.                       
                                                 Demo f =                                     new                                     Demo();                       
                                   
                                                 // Setting Bounds of a Frame.                       
                                                 f.setBounds(                                     200                                     ,                                     200                                     ,                                     400                                     ,                                     300                                     );                       
                                   
                                                 // Setting Resizable status of frame as false                       
                                                 f.setResizable(                                     false                                     );                       
                                   
                                                 // Setting Visible status of frame as true.                       
                                                 f.setVisible(                                     true                                     );                       
                                                 }                       
                         }                       

输出：

图片[2]-Java（GUI）中的消息对话框-yiteyi-C++库

JAVA

                         // Java program to show QUESTION_MESSAGE                       
                         // dialog in Java. Importing different Package.                       
                         import                                     java.awt.*;                       
                         import                                     java.awt.event.*;                       
                         import                                     javax.swing.*;                       
           
                         class                                     Demo                                     extends                                     JFrame                                     implements                                     ActionListener                       
                         {                       
                                                 // Declaration of object of JButton class.                       
                                                 JButton b1;                       
                                   
                                                 // Constructor of Demo class                       
                                                 Demo()                       
                                                 {                       
                                                 // Setting layout as null of JFrame.                       
                                                 this                                     .setLayout(                                     null                                     );                       
                                   
                                                 // Initialization of object of "JButton" class.                       
                                                 b1 =                                     new                                     JButton(                                     "Button 3"                                     );                       
                                   
                                                 // Setting Bounds of a JButton.                       
                                                 b1.setBounds(                                     130                                     ,                                     05                                     ,                                     100                                     ,                                     50                                     );                       
                                   
                                                 //"this" keyword in java refers to current object.                       
                                                 // Adding JButton on JFrame.                       
                                                 this                                     .add(b1);                       
                                   
                                                 // Adding Listener toJButton.                       
                                                 b1.addActionListener(                                     this                                     );                       
                                                 }                       
           
                                                 // Override Method                       
                                                 public                                     void                                     actionPerformed(ActionEvent evt)                       
                                                 {                       
                                                 if                                     (evt.getSource() == b1)                       
                                                 {                       
                                                 // Code TO popup a QUESTION_MESSAGE Dialog.                       
                                                 JOptionPane.showMessageDialog(                                     this                                     ,                                     "Do you want to quit"                                     ,                       
                                                 "Question"                                     , JOptionPane.QUESTION_MESSAGE);                       
                                                 }                       
                                                 }                       
                         }                       
           
                         class                                     MessageDialogs3 {                       
                                   
                                                 // Driver code                       
                                                 public                                     static                                     void                                     main(String args[])                       
                                                 {                       
                                                 // Creating Object of demo class.                       
                                                 Demo f =                                     new                                     Demo();                       
                                   
                                                 // Setting Bounds of a Frame.                       
                                                 f.setBounds(                                     200                                     ,                                     200                                     ,                                     400                                     ,                                     300                                     );                       
                                   
                                                 // Setting Resizable status of frame as false                       
                                                 f.setResizable(                                     false                                     );                       
                                   
                                                 // Setting Visible status of frame as true.                       
                                                 f.setVisible(                                     true                                     );                       
                                                 }                       
                         }                       

输出：

图片[3]-Java（GUI）中的消息对话框-yiteyi-C++库

JAVA

                         // Java program to show INFORMATION_MESSAGE                       
                         // dialog in Java. Importing different Package.                       
                         import                                     java.awt.*;                       
                         import                                     java.awt.event.*;                       
                         import                                     javax.swing.*;                       
           
                         class                                     Demo                                     extends                                     JFrame                                     implements                                     ActionListener                       
                         {                       
                                                 // Declaration of object of JButton class.                       
                                                 JButton b1;                       
                                   
                                                 // Constructor of Demo class                       
                                                 Demo()                       
                                                 {                       
                                                 // Setting layout as null of JFrame.                       
                                                 this                                     .setLayout(                                     null                                     );                       
                                   
                                                 // Initialization of object of "JButton" class.                       
                                                 b1 =                                     new                                     JButton(                                     "Button 4"                                     );                       
                                   
                                                 // Setting Bounds of a JButton.                       
                                                 b1.setBounds(                                     130                                     ,                                     05                                     ,                                     100                                     ,                                     50                                     );                       
                                   
                                                 //"this" keyword in java refers to current object.                       
                                                 // Adding JButton on JFrame.                       
                                                 this                                     .add(b1);                       
                                   
                                                 // Adding Listener toJButton.                       
                                                 b1.addActionListener(                                     this                                     );                       
                                                 }                       
           
                                                 // Override Method                       
                                                 public                                     void                                     actionPerformed(ActionEvent evt)                       
                                                 {                       
                                                 if                                     (evt.getSource() == b1)                       
                                                 {                       
                                                 // Code To popup an INFORMATION_MESSAGE Dialog.                       
                                                 JOptionPane.showMessageDialog(                                     this                                     ,                                     "You Pressed Button FOUR"                                     ,                       
                                                 "INFORMATION"                                     ,                       
                                                 JOptionPane.INFORMATION_MESSAGE);                       
                                                 }                       
                                                 }                       
                         }                       
           
                         class                                     MessageDialogs4 {                       
                                   
                                                 // Driver code                       
                                                 public                                     static                                     void                                     main(String args[])                       
                                                 {                       
                                   
                                                 // Creating Object of demo class.                       
                                                 Demo f =                                     new                                     Demo();                       
                                   
                                                 // Setting Bounds of a Frame.                       
                                                 f.setBounds(                                     200                                     ,                                     200                                     ,                                     400                                     ,                                     300                                     );                       
                                   
                                                 // Setting Resizable status of frame as false                       
                                                 f.setResizable(                                     false                                     );                       
                                   
                                                 // Setting Visible status of frame as true.                       
                                                 f.setVisible(                                     true                                     );                       
                                                 }                       
                         }                       

输出：

图片[4]-Java（GUI）中的消息对话框-yiteyi-C++库

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