How to set and get thread priority in Java?

View and modify thread priority

1. Question

Each thread in JAVA has an optimization level attribute. By default, the priority of the newly created thread and the thread that created the thread it's the same. When the thread scheduler selects a thread to run, it selects the thread with the highest priority.

Implementation: View and modify the priority of threads

2. Problem-solving ideas

Create a class: ThreadPriorityTest, which inherits JFrame. Used to interface to display the threads running in the current thread group.

Define 2 methods:

• do_this_windowActivated(): used to listen for form activation events

• do_button_actionPerformed(): Used to click the modify button event, obtain the user input priority and selected row, and modify the thread priority.

Thread is the execution thread in the program. The JAVA virtual machine allows applications to run multiple execution threads concurrently.

3. Detailed code explanation

package com.xiaoxuzhu;

import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Font;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.JTextField;
import javax.swing.UIManager;
import javax.swing.border.EmptyBorder;
import javax.swing.table.DefaultTableModel;
import javax.swing.table.JTableHeader;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
/**
 * Description: 
 *
 * @author xiaoxuzhu
 * @version 1.0
 *
 * <pre class="brush:php;toolbar:false">
 * 修改记录:
 * 修改后版本	        修改人		修改日期			修改内容
 * 2022/5/11.1	    xiaoxuzhu		2022/5/11		    Create
 * 

* @date 2022/5/11 */ public class ThreadPriorityTest extends JFrame { /** * */ private static final long serialVersionUID = 1127454227002083871L; private JPanel contentPane; private JTable table; private JTextField textField; /** * Launch the application. */ public static void main(String[] args) { try { UIManager.setLookAndFeel("com.sun.java.swing.plaf.nimbus.NimbusLookAndFeel"); } catch (Throwable e) { e.printStackTrace(); } EventQueue.invokeLater(new Runnable() { public void run() { try { ThreadPriorityTest frame = new ThreadPriorityTest(); frame.setVisible(true); } catch (Exception e) { e.printStackTrace(); } } }); } /** * Create the frame. */ public ThreadPriorityTest() { addWindowListener(new WindowAdapter() { @Override public void windowActivated(WindowEvent e) { do_this_windowActivated(e); } }); setTitle("查看和修改线程优化级"); setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); setBounds(100, 100, 450, 300); contentPane = new JPanel(); contentPane.setBorder(new EmptyBorder(5, 5, 5, 5)); contentPane.setLayout(new BorderLayout(0, 0)); setContentPane(contentPane); JPanel panel = new JPanel(); contentPane.add(panel, BorderLayout.SOUTH); JLabel label = new JLabel("新优先级（1~10）"); label.setFont(new Font("微软雅黑", Font.PLAIN, 16)); panel.add(label); textField = new JTextField(); textField.setFont(new Font("微软雅黑", Font.PLAIN, 16)); panel.add(textField); textField.setColumns(10); JButton button = new JButton("修改"); button.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { do_button_actionPerformed(e); } }); button.setFont(new Font("微软雅黑", Font.PLAIN, 16)); panel.add(button); JScrollPane scrollPane = new JScrollPane(); contentPane.add(scrollPane, BorderLayout.CENTER); table = new JTable(); table.setFont(new Font("微软雅黑", Font.PLAIN, 14)); table.setRowHeight(30); JTableHeader header = table.getTableHeader(); header.setFont(new Font("微软雅黑", Font.PLAIN, 16)); header.setPreferredSize(new Dimension(header.getWidth(), 35)); scrollPane.setViewportView(table); } protected void do_this_windowActivated(WindowEvent e) { ThreadGroup group = Thread.currentThread().getThreadGroup();// 获得当前线程所在线程组 Thread[] threads = new Thread[group.activeCount()];// 使用数组保存活动状态的线程 group.enumerate(threads);// 获得所有线程 DefaultTableModel model = (DefaultTableModel) table.getModel(); // 获得表格模型 model.setRowCount(0); // 清空表格模型中的数据 model.setColumnIdentifiers(new Object[] { "线程ID", "线程名称", "优先级" }); // 定义表头 for (Thread thread : threads) {// 增加行数据 model.addRow(new Object[] { thread.getId(), thread.getName(), thread.getPriority() }); } table.setModel(model);// 更新表格模型 } protected void do_button_actionPerformed(ActionEvent e) { String text = textField.getText(); Integer priority = Integer.parseInt(text); int selectedRow = table.getSelectedRow(); DefaultTableModel model = (DefaultTableModel) table.getModel(); model.setValueAt(priority, selectedRow, 2); repaint(); } }

Thread list and corresponding priority:

Modify thread priority:

Modification result:

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