Properties load(InputStream) in Java

load(InputStream): This method is available in java.util.Properties class of Java.

Syntax:

void java.util.Properties.load(InputStream inStream) throws IOException

This method takes one argument. This method reads a property list (key and element pairs) from the input byte stream.

Parameters: One parameter is required for this method.

inStream: the input stream.

Throws:

1. IOException - if an error occurred when reading from the input stream.

2. IllegalArgumentException - if the input stream contains a malformed Unicode escape sequence.

3. NullPointerException - if inStream is null.

Approach 1: When no exception

Java

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.Properties;

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

        Properties properties = new Properties();

        String str = "C++ Programming Language";
        String str2 = "Java Programming Language";

        FileInputStream inStream = 
               new FileInputStream("hello.txt");

        @SuppressWarnings("resource")
        FileOutputStream fileOutputStream =  
            new FileOutputStream("hello.txt");
        fileOutputStream.write(str.getBytes());
        fileOutputStream.write("\n".getBytes());
        fileOutputStream.write(str2.getBytes());
        properties.load(inStream);

        properties.list(System.out);
    }
}

Output:

-- listing properties --

Java=Programming Language

C++=Programming Language

Approach 2: NullPointerException

Java

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.Properties;

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

        Properties properties = new Properties();

        String str = "C++ Programming Language";
        String str2 = "Java Programming Language";

        FileInputStream inStream = null;

        @SuppressWarnings("resource")
        FileOutputStream fileOutputStream = 
                 new FileOutputStream("hello.txt");
        fileOutputStream.write(str.getBytes());
        fileOutputStream.write("\n".getBytes());
        fileOutputStream.write(str2.getBytes());
        properties.load(inStream);

        properties.list(System.out);
    }
}

Output:

Exception in thread "main" java.lang.NullPointerException: inStream parameter is null
	at java.base/java.util.Objects.requireNonNull(Objects.java:233)
	at java.base/java.util.Properties.load(Properties.java:407)