CODEWITHSUNDEEP
javalinuxterminalcentos
CodeMed
CodeMed

Reputation: 9205

getting a Java program to write to CentOS 7 terminal

From the CentOS 7 terminal, I can run the java program below by typing javac /path/to/TestJDBC.java. But the problem is that the SYSO commands in the program have no place to go when called from the terminal. How can I change the Java code below so that the SYSO commands get printed to the terminal instead? I know that I could use a FileOutputStream() and then nano the created file name, but I would like to avoid creating a bunch of unnecessary test files.

package somepackage;
//STEP 1. Import required packages
import java.sql.*;

public class TestJDBC {
 // JDBC driver name and database URL
 static final String JDBC_DRIVER = "com.mysql.jdbc.Driver";  
 static final String DB_URL = "jdbc:mysql://localhost:3306/somedb?autoReconnect=true";

 //  Database credentials
 static final String USER = "usrname";
 static final String PASS = "pword";

 public static void main(String[] args) {
 Connection conn = null;
 Statement stmt = null;
 try{
    //STEP 2: Register JDBC driver
    Class.forName("com.mysql.jdbc.Driver");

    //STEP 3: Open a connection
    System.out.println("Connecting to database...");
    conn = DriverManager.getConnection(DB_URL,USER,PASS);

    //STEP 4: Execute a query
    System.out.println("Creating statement...");
    stmt = conn.createStatement();
    String sql;
    sql = "SELECT id, name FROM peeps";
    ResultSet rs = stmt.executeQuery(sql);

    //STEP 5: Extract data from result set
    while(rs.next()){
       //Retrieve by column name
       int id  = rs.getInt("id");
       String name = rs.getString("name");

       //Display values
       System.out.print("ID: " + id);
       System.out.println(", name: " + name);
    }
    //STEP 6: Clean-up environment
    rs.close();
    stmt.close();
    conn.close();
 }catch(SQLException se){
    //Handle errors for JDBC
    se.printStackTrace();
 }catch(Exception e){
    //Handle errors for Class.forName
    e.printStackTrace();
 }finally{
    //finally block used to close resources
    try{
       if(stmt!=null)
          stmt.close();
    }catch(SQLException se2){
    }// nothing we can do
    try{
       if(conn!=null)
          conn.close();
    }catch(SQLException se){
       se.printStackTrace();
    }//end finally try
 }//end try
 System.out.println("Goodbye!");
}//end main
}//end FirstExample

EDIT

I tried @Immibis's method, and the program starts to run by throws a java.lang.ClassNotFoundException: com.mysql.jdbc.Driver error at the line of code that says Class.forName("com.mysql.jdbc.Driver");. I cannot really evaluate the ability of the program to print to the terminal until errors like this are resolved. How can I resolve this and similar errors in the simple code above?

Upvotes: 1

Views: 487

Answers (1)

Stack Exchange Broke The Law
Stack Exchange Broke The Law

Reputation: 58947

javac is the compiler. You are compiling your program, but not running it.

Since your package is somepackage, you should have a folder somepackage containing TestJDBC.java. cd to that folder, then run:

javac somepackage/TestJDBC.java
java somepackage.TestJDBC

(It is usually a good idea to make your source folders follow your package structure)

Upvotes: 1

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