Java ProcessBuilder start() Method

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Description

The Java ProcessBuilder start() method starts a new process using the attributes of this process builder. The new process will invoke the command and arguments given by command(), in a working directory as given by directory(), with a process environment as given by environment(). This method checks that the command is a valid operating system command. Which commands are valid is system-dependent, but at the very least the command must be a non-empty list of non-null strings.

If there is a security manager, its checkExec method is called with the first component of this object's command array as its argument. This may result in a SecurityException being thrown.

Declaration

Following is the declaration for java.lang.ProcessBuilder.start() method

public Process start()

Parameters

NA

Return Value

This method returns a new Process object for managing the subprocess

Exception

• NullPointerException − If an element of the command list is null

• IndexOutOfBoundsException − If the command is an empty list (has size 0)

• SecurityException − If a security manager exists and its checkExec method doesn't allow creation of the subprocess

• IOException − If an I/O error occurs

Starting a Notepad process using Process Builder Example

The following example shows the usage of ProcessBuilder start() method. In this program, we've created an array of Strings and added notepad.exe and test.txt to it. Using that list, we've initialized a ProcessBuilder instance. Now using start() method, we've started the process.

package com.tutorialspoint;

import java.io.IOException;

public class ProcessBuilderDemo {

   public static void main(String[] args) {

      // create a new list of arguments for our process
      String[] list = {"notepad.exe", "test.txt"};

      // create the process builder
      ProcessBuilder pb = new ProcessBuilder(list);
      try {
         // start the subprocess
         System.out.println("Starting the process..");
         pb.start();
      } catch (IOException ex) {
         ex.printStackTrace();
      }
   }
}

Output

Let us compile and run the above program, this will produce the following result −

Starting the process..

Starting a Calculator process using Process Builder Example

The following example shows the usage of ProcessBuilder start() method. In this program, we've created an array of Strings and added calc.exe. Using that list, we've initialized a ProcessBuilder instance. Now using start() method, we've started the process.

package com.tutorialspoint;

import java.io.IOException;

public class ProcessBuilderDemo {

   public static void main(String[] args) {

      // create a new list of arguments for our process
      String[] list = {"calc.exe"};

      // create the process builder
      ProcessBuilder pb = new ProcessBuilder(list);
      try {
         // start the subprocess
         System.out.println("Starting the process..");
         pb.start();
      } catch (IOException ex) {
         ex.printStackTrace();
      }
   }
}

Output

Let us compile and run the above program, this will produce the following result −

Starting the process..

Starting a Windows Explorer process using Process Builder Example

The following example shows the usage of ProcessBuilder start() method. In this program, we've created an array of Strings and added explorer.exe. Using that list, we've initialized a ProcessBuilder instance. Now using start() method, we've started the process.

package com.tutorialspoint;

import java.io.IOException;

public class ProcessBuilderDemo {

   public static void main(String[] args) {

      // create a new list of arguments for our process
      String[] list = {"explorer.exe"};

      // create the process builder
      ProcessBuilder pb = new ProcessBuilder(list);
      try {
         // start the subprocess
         System.out.println("Starting the process..");
         pb.start();
      } catch (IOException ex) {
         ex.printStackTrace();
      }
   }
}

Output

Let us compile and run the above program, this will produce the following result −

Starting the process..