1. Sort integer array ?
public class SortedArray
{
public static void main(String[] args) {
int a[]={30,7,9,20};
Arrays.sort(a);
System.out.println(Arrays.toString(a));
}
}
2. Sort integer array without using Array.sort by ascending
public class ArraySort {
public static void main(String[] args) {
int a[] = {6,500,700,200,1000,1};
int temp=0;
/*** Ascending Order ***/
for(int i=0;i<a.length;i++)
{
for(int j=a.length-1;j>i;j--)
{
if(a[i]>a[j]){
temp = a[i];
a[i] = a[j];
a[j] = temp;
}
}
}
for(int i=0;i<a.length;i++)
System.out.println("a["+i+"] = "+a[i]);
}
}
3. Sort integer array without using Array.sort by decending
public class Test {
public static void main(String[] args)
{
int a[] = {6,500,700,200,1000,1};
int temp=0;
/*** Descending Order***/
for(int i=0;i<a.length;i++)
{
for(int j=0;j<a.length;j++)
{
if(a[i]>a[j]){
temp = a[i];
a[i] = a[j];
a[j] = temp;
}
}
}
for(int i=0;i<a.length;i++)
System.out.println("a["+i+"] = "+a[i]);
}
}
4. why need to use overriding ?
Consider Manager is a super class and Employee is a child class.
Both class has work() .
But in Manager,he only manage and in Employee, he will do coding. But basically Manager and Employee are worker.
Their work is different based on class.
5. What is Generic ?
A class or interface that operates on parameterized type is called Generic.
Generic also provide type safety.
we cannot use other class object .
6.How to sort employee details using comparable ?
class Student implements Comparable<Student> {
int rollno;
String name;
int age;
public int getRollno() {
return rollno;
}
public void setRollno(int rollno) {
this.rollno = rollno;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public int compareTo(Student obj)
{
return this.rollno - obj.rollno;
}
}
public class Simple {
public static void main(String[] args) {
ArrayList al = new ArrayList();
Student a = new Student();
a.setAge(2);
a.setName("bala");
a.setRollno(5);
Student b = new Student();
b.setAge(1);
b.setName("sures");
b.setRollno(67);
Student c = new Student();
c.setAge(8);
c.setName("ramesh");
c.setRollno(43);
al.add(a);
al.add(b);
al.add(c);
Collections.sort(al);
Iterator itr = al.iterator();
while(itr.hasNext())
{
Student st=(Student)itr.next();
System.out.println(st.age+" "+st.name+" "+st.rollno);
}
}
}
7. Reverse the string ?
public class StringReverseExample{
public static void main(String[] args){
String string="How to name it";
String reverse = new StringBuffer(string).
reverse().toString();
System.out.println("\nString before reverse:" +string);
System.out.println("String after reverse:"+reverse);
}
}
8.Difference between executeUpdate and executeQuery ?
int executeUpdate(String SQL) : Returns the numbers of rows affected by the execution of the SQL statement. Use this method to execute SQL statements for which you expect to get a number of rows affected - for example, an INSERT, UPDATE, or DELETE statement.
ResultSet executeQuery(String SQL) : Returns a ResultSet object. Use this method when you expect to get a result set, as you would with a SELECT statement.
