j29

/*

1. Write a Java program to display information about all columns in the DONAR table
   using ResultSetMetaData.
   */
   package com.mycompany.javaslip;

import java.sql.*;

public class slip29_1
{
public static void main(String[] args) throws SQLException {
Connection conn = DriverManager.getConnection("jdbc:postgresql://localhost:5432/postgres", "postgres", "postgres");

    String sql = "select * from donar";
    
    Statement stmt = conn.createStatement();
    stmt.executeQuery(sql);
    
    ResultSet rs = stmt.getResultSet();
    ResultSetMetaData rsmd = rs.getMetaData();
    
    int colCnt = rsmd.getColumnCount();
    System.out.println("Donar table Meta Data:");
    for(int i=1; i<colCnt; i++) {
        String colName = rsmd.getColumnName(i);
        String colType = rsmd.getColumnTypeName(i);
        int colSize = rsmd.getColumnDisplaySize(i);
        
        System.out.println(colName + " " + colType + "(" + colSize + ")");
    }
}

}

/*
2. Write a Java program to create LinkedList of integer objects and perform the following:
i. Add element at first position
ii. Delete last element
iii. Display the size of link list
*/
package com.mycompany.javaslip;

import java.util.*;

public class slip29_2
{
public static void main(String[] args) {
List<Integer> l = new LinkedList<>();
Scanner sc = new Scanner(System.in);

    int ch;
    
    do {
        System.out.println("Menu");
        System.out.println("1. Insert at head");
        System.out.println("2. Delete tail.");
        System.out.println("3. Display size");
        System.out.println("4. Exit");
        
        System.out.println("------------------------------");
        System.out.println("Enter your choice:");
        ch = sc.nextInt();
        System.out.println();
        
        switch(ch) {
            case 1: System.out.println("Enter a number:");
                l.addFirst(sc.nextInt());
                break;
            case 2: l.removeLast();
                break;
            case 3: 
                System.out.println("Size : " + l.size() + "\n" + l);
                break;
            default: System.out.println("Invalid choice.");
        }
        System.out.println("-------------------------------");
    } while(ch != 4);
}

}