ProcessBuilder.startPipeline(List) in Java

ProcessBuilder.startPipeline(List<ProcessBuilder>): This method is available in the java.lang.ProcessBuilder class of Java.

Syntax:

List<Process> java.lang.ProcessBuilder.startPipeline(List<ProcessBuilder> builders) throws IOException

This method takes one argument. This method starts a Process for each ProcessBuilder, creating a pipeline of processes linked by their standard output and standard input streams.

Parameters: One parameter is required for this method.

builders: a List of ProcessBuilders.

Returns: a List<Process> started from the corresponding ProcessBuilder.

Throws:

1. IllegalArgumentException - any of the redirects except the standard input of the first builder and the standard output of the last builder are not Redirect.PIPE.

2. NullPointerException - if an element of the command list is null or if an element of the ProcessBuilder list is null or the builders argument is null.

3. IndexOutOfBoundsException - if the command is an empty list.

4. SecurityException - if a security manager exists and

a). its checkExecmethod doesn't allow creation of the subprocess.

b). the standard input to the subprocess was redirected from a file and the security manager's checkRead method denies read access to the file.

c). the standard output or standard error of the subprocess was redirected to a file and the security manager's checkWrite method denies write access to the file.

5. UnsupportedOperationException - If the operating system does not support the creation of processes.

6. IOException - if an I/O error occurs.

Approach 1: When no exception

Java

package com.ProcessBuilder;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

public class ProcessBuilderstartPipeline {
    public static void main(String[] args) throws IOException {

        ProcessBuilder processBuilder = 
                    new ProcessBuilder("notepad.exe");

        ProcessBuilder processBuilder2 =
                      new ProcessBuilder("notepad.exe");

        List<ProcessBuilder> list = 
                        new ArrayList<ProcessBuilder>();
        list.add(processBuilder);
        list.add(processBuilder2);

        System.out.println(ProcessBuilder.startPipeline(list));
    }
}

Output:

[Process[pid=8000, exitValue="not exited"], Process[pid=12080, exitValue="not exited"]]

Approach 2: NullPointerException 

Java

package com.ProcessBuilder;

import java.io.IOException;
import java.util.List;

public class ProcessBuilderstartPipeline {
    public static void main(String[] args) throws IOException {

        List<ProcessBuilder> list = null;

        System.out.println(ProcessBuilder.startPipeline(list));
    }
}

Output:

Exception in thread "main" java.lang.NullPointerException: Cannot invoke "java.util.List.size()" because "builders" is null
	at java.base/java.lang.ProcessBuilder.startPipeline(ProcessBuilder.java:1272)
	at com.ProcessBuilder.ProcessBuilderstartPipeline.main(ProcessBuilderstartPipeline.java:11)

Approach 3: IOException 

Java

package com.ProcessBuilder;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

public class ProcessBuilderstartPipeline {
    public static void main(String[] args) throws IOException {

        ProcessBuilder processBuilder = 
                        new ProcessBuilder("notepad.exe");

        ProcessBuilder processBuilder2 = 
                          new ProcessBuilder("hello.exe");

        List<ProcessBuilder> list = 
                      new ArrayList<ProcessBuilder>();
        list.add(processBuilder);
        list.add(processBuilder2);

        System.out.println(ProcessBuilder.startPipeline(list));
    }
}

Output:

Exception in thread "main" java.io.IOException: Cannot run program "hello.exe": CreateProcess error=2, The system cannot find the file specified
	at java.base/java.lang.ProcessBuilder.start(ProcessBuilder.java:1142)
	at java.base/java.lang.ProcessBuilder.startPipeline(ProcessBuilder.java:1297)
	at com.ProcessBuilder.ProcessBuilderstartPipeline.main(ProcessBuilderstartPipeline.java:18)
Caused by: java.io.IOException: CreateProcess error=2, The system cannot find the file specified
	at java.base/java.lang.ProcessImpl.create(Native Method)
	at java.base/java.lang.ProcessImpl.<init>(ProcessImpl.java:483)
	at java.base/java.lang.ProcessImpl.start(ProcessImpl.java:158)
	at java.base/java.lang.ProcessBuilder.start(ProcessBuilder.java:1109)
	... 2 more

Some methods of ProcessBuilder class

ProcessBuilder.ProcessBuilder(String...): This method constructs a process builder with the specified operating system program and arguments.

ProcessBuilder.ProcessBuilder(List<String>): This method constructs a process builder with the specified operating system program and arguments.

command(): This method returns this process builder's operating system program and arguments.

command(List<String>): This method sets this process builder's operating system program and arguments.

command(String...): This method sets this process builder's operating system program and arguments. 

directory(): This method returns this process builder's working directory.

directory(File): This method sets this process builder's working directory.

environment(): This method returns a string map view of this process builder's environment.

inheritIO(): This method sets the source and destination for subprocess standard I/O to be the same as those of the current Java process.

redirectError(): This method returns this process builder's standard error destination.

redirectError(File): This method sets this process builder's standard error destination to a file.

redirectError(Redirect): This method sets this process builder's standard error destination.

redirectErrorStream(): This method tells whether this process builder merges standard error and standard output.

redirectErrorStream(boolean): This method sets this process builder's redirectErrorStream property.

redirectInput(): This method returns this process builder's standard input source.

redirectInput(File): This method sets this process builder's standard input source to a file.

redirectInput(Redirect): This method sets this process builder's standard input source.

redirectOutput(): This method returns this process builder's standard output destination.

redirectOutput(File): This method sets this process builder's standard output destination to a file.

redirectOutput(Redirect): This method sets this process builder's standard output destination.

start(): This method starts a new process using the attributes of this process builder.

ProcessBuilder.startPipeline(List<ProcessBuilder>): his method starts a Process for each ProcessBuilder, creating a pipeline of processes linked by their standard output and standard input streams.