class MyThread extends Thread{
 private static int num = 0;
 
 public MyThread(){
 num++;
 }
 
 @Override
 public void run() {
 System.out.println("主动创建的第"+num+"个线程");
 }
}

public class Test {
 public static void main(String[] args) {
 MyThread thread = new MyThread();
 thread.start();
 }
}
 
class MyThread extends Thread{
 private static int num = 0;
 
 public MyThread(){
 num++;
 }
 
 @Override
 public void run() {
 System.out.println("主动创建的第"+num+"个线程");
 }
}

public class Test {
 public static void main(String[] args) {
 System.out.println("主线程ID:"+Thread.currentThread().getId());
 MyThread thread1 = new MyThread("thread1");
 thread1.start();
 MyThread thread2 = new MyThread("thread2");
 thread2.run();
 }
}
 
class MyThread extends Thread{
 private String name;
 
 public MyThread(String name){
 this.name = name;
 }
 
 @Override
 public void run() {
 System.out.println("name:"+name+" 子线程ID:"+Thread.currentThread().getId());
 }
}

public class Test {
 public static void main(String[] args) {
 System.out.println("主线程ID："+Thread.currentThread().getId());
 MyRunnable runnable = new MyRunnable();
 Thread thread = new Thread(runnable);
 thread.start();
 }
}
 
class MyRunnable implements Runnable{
 
 public MyRunnable() {
 
 }
 
 @Override
 public void run() {
 System.out.println("子线程ID："+Thread.currentThread().getId());
 }
}

public class Test {
 public static void main(String[] args) {
 System.out.println("主线程ID："+Thread.currentThread().getId());
 MyRunnable runnable = new MyRunnable();
 Thread thread = new Thread(runnable);
 thread.start();
 }
}
 
class MyRunnable implements Runnable{
 
 public MyRunnable() {
 
 }
 
 @Override
 public void run() {
 System.out.println("子线程ID："+Thread.currentThread().getId());
 }
}

public final class ProcessBuilder
{
 private List<String> command;
 private File directory;
 private Map<String,String> environment;
 private boolean redirectErrorStream;
 
 public ProcessBuilder(List<String> command) {
 if (command == null)
 throw new NullPointerException();
 this.command = command;
 }
 
 public ProcessBuilder(String... command) {
 this.command = new ArrayList<String>(command.length);
 for (String arg : command)
 this.command.add(arg);
 }
....
}

public Process start() throws IOException {
// Must convert to array first -- a malicious user-supplied
// list might try to circumvent the security check.
String[] cmdarray = command.toArray(new String[command.size()]);
for (String arg : cmdarray)
 if (arg == null)
 throw new NullPointerException();
// Throws IndexOutOfBoundsException if command is empty
String prog = cmdarray[0];
 
SecurityManager security = System.getSecurityManager();
if (security != null)
 security.checkExec(prog);
 
String dir = directory == null ? null : directory.toString();
 
try {
 return ProcessImpl.start(cmdarray,
 environment,
 dir,
 redirectErrorStream);
} catch (IOException e) {
 // It's much easier for us to create a high-quality error
 // message than the low-level C code which found the problem.
 throw new IOException(
 "Cannot run program "" + prog + """
 + (dir == null ? "" : " (in directory "" + dir + "")")
 + ": " + e.getMessage(),
 e);
}
}

return ProcessImpl.start(cmdarray,
 environment,
 dir,
 redirectErrorStream);

final class ProcessImpl extends Process {
 
 // System-dependent portion of ProcessBuilder.start()
 static Process start(String cmdarray[],
 java.util.Map<String,String> environment,
 String dir,
 boolean redirectErrorStream)
 throws IOException
 {
 String envblock = ProcessEnvironment.toEnvironmentBlock(environment);
 return new ProcessImpl(cmdarray, envblock, dir, redirectErrorStream);
 }
 ....
}

public class Test {
 public static void main(String[] args) throws IOException {
 ProcessBuilder pb = new ProcessBuilder("cmd","/c","ipconfig/all");
 Process process = pb.start();
 Scanner scanner = new Scanner(process.getInputStream());
 
 while(scanner.hasNextLine()){
 System.out.println(scanner.nextLine());
 }
 scanner.close();
 }
}

public class Runtime {
 private static Runtime currentRuntime = new Runtime();
 
 /**
 * Returns the runtime object associated with the current Java application.
 * Most of the methods of class <code>Runtime</code> are instance
 * methods and must be invoked with respect to the current runtime object.
 *
 * @return the <code>Runtime</code> object associated with the current
 * Java application.
 */
 public static Runtime getRuntime() {
 return currentRuntime;
 }
 
 /** Don't let anyone else instantiate this class */
 private Runtime() {}
 ...
 }

public Process exec(String[] cmdarray, String[] envp, File dir)
 throws IOException {
 return new ProcessBuilder(cmdarray)
 .environment(envp)
 .directory(dir)
 .start();
 }

public class Test {
 public static void main(String[] args) throws IOException {
 String cmd = "cmd "+"/c "+"ipconfig/all";
 Process process = Runtime.getRuntime().exec(cmd);
 Scanner scanner = new Scanner(process.getInputStream());
 
 while(scanner.hasNextLine()){
 System.out.println(scanner.nextLine());
 }
 scanner.close();
 }
}