Método StringJoiner merge() en Java

La combinación (StringJoiner other) de StringJoiner agrega el contenido del StringJoiner dado sin prefijo y sufijo como el siguiente elemento si no está vacío. Si el StringJoiner dado está vacío, la llamada no tiene efecto.
Sintaxis: 
 

public StringJoiner merge(StringJoiner other)

Parámetros: este método acepta otro parámetro obligatorio, que es StringJoiner , cuyo contenido debe fusionarse con este
. Devuelve: este método devuelve este StringJoiner
. Excepción: este método genera una excepción NullPointerException si el otro StringJoiner es nulo
.
1: Para demostrar merge() con delimitador ” “
 

// Java program to demonstrate
// merge() method of StringJoiner
 
import java.util.StringJoiner;
 
public class GFG {
    public static void main(String[] args)
    {
 
        // Creating StringJoiner with delimiter " "
        StringJoiner str1 = new StringJoiner(" ");
 
        // Adding elements in the StringJoiner
        str1.add("Geeks");
        str1.add("for");
        str1.add("Geeks");
 
        // Print the StringJoiner
        System.out.println("StringJoiner 1: "
                           + str1.toString());
 
        // Creating the second StringJoiner
        StringJoiner str2 = new StringJoiner(" ");
 
        str2.add("A");
        str2.add("Computer");
        str2.add("Portal");
 
        // Print the second StringJoiner
        System.out.println("StringJoiner 2: "
                           + str2.toString());
 
        // Merging the StringJoiner using merge()
        StringJoiner str = str1.merge(str2);
 
        // Printing the merged StringJoiner
        System.out.println("Merged StringJoiner : "
                           + str);
    }
}

StringJoiner 1: Geeks for Geeks
StringJoiner 2: A Computer Portal
Merged StringJoiner : Geeks for Geeks A Computer Portal

Ejemplo 2: Para demostrar merge() con delimitador “, “
 

// Java program to demonstrate
// merge() method of StringJoiner
 
import java.util.StringJoiner;
 
public class GFG1 {
    public static void main(String[] args)
    {
 
        // Creating StringJoiner with delimiter ", "
        StringJoiner str1 = new StringJoiner(", ");
 
        // Adding elements in the StringJoiner
        str1.add("Geeks");
        str1.add("for");
        str1.add("Geeks");
 
        // Print the StringJoiner
        System.out.println("StringJoiner 1: "
                           + str1.toString());
 
        // Creating the second StringJoiner
        StringJoiner str2 = new StringJoiner(", ");
 
        str2.add("A");
        str2.add("Computer");
        str2.add("Portal");
 
        // Print the StringJoiner
        System.out.println("StringJoiner 2: "
                           + str2.toString());
 
        // Merging the StringJoiner using merge()
        StringJoiner str = str1.merge(str2);
 
        // Printing the merged StringJoiner
        System.out.println("Merged StringJoiner : "
                           + str);
    }
}

StringJoiner 1: Geeks, for, Geeks
StringJoiner 2: A, Computer, Portal
Merged StringJoiner : Geeks, for, Geeks, A, Computer, Portal

Ejemplo 3: Para demostrar NullPointerException
 

// Java program to demonstrate
// merge() method of StringJoiner
 
import java.util.StringJoiner;
 
public class GFG1 {
    public static void main(String[] args)
    {
 
        // Creating StringJoiner with delimiter ", "
        StringJoiner str1 = new StringJoiner(", ");
 
        // Adding elements in the StringJoiner
        str1.add("Geeks");
        str1.add("for");
        str1.add("Geeks");
 
        // Print the StringJoiner
        System.out.println("StringJoiner 1: "
                           + str1.toString());
 
        // Creating the second StringJoiner
        // to be merged as null
        StringJoiner str2 = null;
 
        // Print the StringJoiner
        System.out.println("StringJoiner 2: "
                           + str2);
 
        try {
 
            // Merging the StringJoiner using merge()
            StringJoiner str = str1.merge(str2);
        }
        catch (Exception e) {
            System.out.println("Exception during merge: "
                               + e);
        }
    }
}

StringJoiner 1: Geeks, for, Geeks
StringJoiner 2: null
Exception during merge: java.lang.NullPointerException