CREATE OR REPLACE AND COMPILE JAVA SOURCE NAMED "welcome" 
AS
public class welcome {

	public static String msg() {
		return "Welcome to https://www.oracleplsqltr.com/";
	}
	
};
/

CREATE OR REPLACE FUNCTION f_java
RETURN VARCHAR2 
AS
LANGUAGE JAVA NAME 'welcome.msg() return java.lang.String';
/

declare
    v_return varchar2(500);
begin
    v_return := f_java;
    dbms_output.put_line(v_return);
end;
/

F_JAVA
--------------------------------------------------------------------------------
Welcome to https://www.oracleplsqltr.com/

SELECT object_name, object_type, status FROM user_objects WHERE object_type like '%JAVA%';


OBJECT_NAME                    OBJECT_TYPE                    STATUS
------------------------------ ------------------------------ --------------------------
welcome                        JAVA CLASS                     VALID
welcome                        JAVA SOURCE                    VALID

BEGIN
 
DBMS_JAVA.GRANT_PERMISSION(
                           'DB_USER',
                           'SYS:java.io.FilePermission',
                           '<<ALL FILES>>',
                           'read,write,delete,execute'
                           );
 
END;

CREATE OR REPLACE AND COMPILE JAVA SOURCE NAMED "jos" 
AS
import java.io.*;

public class jos {
	
	public static String run_os_cmd(String p_cmd) {
		Process process;
		String ln = "";
		
		try {
			
			process = Runtime.getRuntime().exec(p_cmd);
			ln = printResults(process);
			
		} catch (IOException e) {
			e.printStackTrace();
		}
		
		return ln;
			
	}
	
	public static String printResults(Process process) throws IOException {
		
	    BufferedReader reader = new BufferedReader(new InputStreamReader(process.getInputStream()));
	    String line = "";
	    String line2 = "";
	    
	    while ((line = reader.readLine()) != null) {
	        //System.out.println(line);
	    	line2 += line + "\n";
	    }
	    
	    return line2;
	}	
	
};
/

CREATE OR REPLACE FUNCTION f_execute_cmd(p_cmd varchar2)
RETURN VARCHAR2 
AS
LANGUAGE JAVA NAME 'jos.run_os_cmd(java.lang.String) return java.lang.String';
/

declare
    v_return varchar2(4000);
begin
    v_return := f_execute_cmd('pwd');
    dbms_output.put_line(v_return);
end;

/opt/oracle/product/19.0.0/dbhome_1/dbs

DROP JAVA SOURCE "jcalc";

DROP PROCEDURE JAVA_TEST_CALC;

DROP PROCEDURE PLSQL_TEST_CALC;

CREATE OR REPLACE AND COMPILE JAVA SOURCE NAMED "jcalc"
AS
public class jcalc {
 
    public static void test_calc(int p_iteration) {
     
        int ind = 0;
        int iteration = 0;
        int innerloop = 0;
        double sum = 0.0;
        int array_length = p_iteration;
        double[] arr = new double[array_length];
         
        for (ind = 0; ind < array_length; ind++)
            arr[ind] = ind;
             
        for (innerloop = 0; innerloop < array_length; innerloop++)
            sum += arr[(iteration + innerloop) % array_length];
        
        System.out.println(Double.valueOf(sum).longValue());
         
        arr = null;
    }
};
/

CREATE OR REPLACE PROCEDURE JAVA_TEST_CALC(P_ITERATION NUMBER)
AS
LANGUAGE JAVA NAME 'jcalc.test_calc(int)';
/

CREATE OR REPLACE PROCEDURE PLSQL_TEST_CALC(P_ITERATION INTEGER)
IS
    v_element integer := 0;
    v_iteration integer := 0;
    v_innerloop integer := 0;
    v_total number := 0.0;
    v_array_length integer := p_iteration;
    type t_arr is table of number;
    arr t_arr := t_arr();
BEGIN

    /* UPDATED as stated in the comment  */
    --SELECT LEVEL BULK COLLECT INTO ARR FROM DUAL CONNECT BY LEVEL <= v_array_length;
    
    FOR I IN 1..v_array_length
    LOOP
        ARR.EXTEND;
        ARR(ARR.COUNT) := I;
    END LOOP;
    
    /* --------------------------------- */
    
    --Index of nested table array start with 1
    v_innerloop := 1;
      
    WHILE v_innerloop < v_array_length
    LOOP
        v_total := v_total + arr(mod((v_iteration + v_innerloop), v_array_length));
        v_innerloop := v_innerloop + 1;
    END LOOP;
      
    dbms_output.put_line(v_total);
      
    arr.delete();
      
END;
/

CALL dbms_java.set_output(2000);
SET SERVEROUTPUT ON;
declare
 
    V_START NUMBER;
     
    PROCEDURE SHOW_ELAPSED_TIME(P_NAME VARCHAR2)
    IS
    BEGIN
        DBMS_OUTPUT.PUT_LINE(P_NAME||' elapsed time: '||TO_CHAR((DBMS_UTILITY.GET_TIME - V_START)/100));
        V_START := DBMS_UTILITY.GET_TIME;
    END;
 
 
begin
 
    V_START := DBMS_UTILITY.GET_TIME;
     
    PLSQL_TEST_CALC(10000000);
     
    SHOW_ELAPSED_TIME('PLSQL');
     
    JAVA_TEST_CALC(10000000);
     
    SHOW_ELAPSED_TIME('Java');
 
end;
/

49999995000000
PLSQL elapsed time: 3,56
49999995000000
Java elapsed time: ,48