Java Study - day1

Install Eclipse

 

create package & class

 

Helloworld class

 

package org.buster.javatutorials.eclipse;

public class Helloworld {

 public static void main(String[] args) {
  System.out.println("Hello world!");
 }
}

 

String class

print string that includes ""

 

public class String {

 public static void main(java.lang.String[] args) {
  System.out.println("egoing said\n\"Welcome programming world\"");
 }
}

 

Variables

Using variables increases recyclability of the codes

For example,

 

System.out.println(100 + 10);

System.out.println((100 + 10) / 10);

System.out.println(((100 + 10) / 10) - 10);

System.out.println((((100 + 10) / 10) - 10) * 10);

 

If I want to change first number 100 to 1000, I have to change all 4 lines. However, if I used variable for 100, I have to change only 1 line. See the below

 

int a = 100;                    //chage to int a = 1000;

System.out.println(a + 10);

System.out.println((a+ 10) / 10);

System.out.println(((a + 10) / 10) - 10);

System.out.println((((a + 10) / 10) - 10) * 10);

 

So, using variables makes it easy for developer to maintenance the codes