final method in int

package com.concretepage;
public class finalMethodInInt {
public static void main(String[] args) {
System.out.println(riskyAction(1));
System.out.println("-----------");
System.out.println(riskyAction(2));
}
public static int riskyAction(int greeting){
try{
if(greeting==1) {
System.out.println(greeting + " from try block");
}else{
throw new Exception();
}
System.exit(100);
return 0;
}
catch(Exception e){
System.out.println(greeting + " from catch block");
return 2;
}
finally{
System.out.println("I am fially block");
System.exit(0);
return 3;
}
//return 4;
    }
}

final Method

package com.concretepage;

public class finalMethod {

public static void main(String[] args) {
System.out.println(riskyAction("hello"));
System.out.println("-----------");
System.out.println(riskyAction("howdy"));
}
public static String riskyAction(String greeting){
try{
if(greeting.equals("hello")){
System.out.println(greeting + " from try block");
}else{
throw new Exception();
}
return "returning from try block";
}catch(Exception e){
System.out.println(greeting + " from catch block");
return "returning from catch block";
}finally{
return "returning from finally block";
}
}
}

Copy Constructor example

package com.concretepage;
public class Complex {
private double re, im;
public Complex(double re, double im) {
this.re = re;
this.im = im;
}
    Complex(Complex c){
    System.out.println("Copy Constructor called");
    re = c.re;
    im = c.im;
    }
    @Override
    public String toString() {
    return "(" + re + " + " + im + "i)";
    } 
}

Character to String example

package com.concretepage;

import java.lang.reflect.Array;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;

import org.hibernate.mapping.Value;

public class CharactertoString {
public static void main(String[] args) {
char[] character = new char[10];
character[0] = 0;  character[1] = 1;
character[2] = 2;  character[3] = 3;
character[4] = 4;  character[5] = 5;
character[6] = 6;  character[7] = 7;
character[8] = 8;  character[9] = 9;
//character[10] = 10;

System.out.println(character.length);

char c = 'S';
System.out.println(String.valueOf(c));
char m = 'M';
System.out.println(Character.toString(m));

for(int k=0;k<character.length;k++) {
System.out.print(character[k]+" ");
}

HashMap<Character, Character> hmap = new HashMap<>();
hmap.put('M', 'N');
hmap.put('O', 'P');

System.out.println();
System.out.println(hmap.get('M'));
System.out.println(hmap.get('O'));


HashMap<String, ArrayList<String>> hmap1 = new LinkedHashMap<>();
ArrayList<String> a1 = new ArrayList<>();
a1.add("1");
a1.add("2");
a1.add("3");
a1.add("4");
hmap1.put("One", a1);hmap1.put("Two", a1);hmap1.put("Three", a1);
hmap1.put("Four", a1);hmap1.put("Five", a1);hmap1.put("Six",  a1);
    System.out.println(hmap1.get("One"));
    System.out.println("hmap1.isEmpty() " + hmap1.isEmpty());
    hmap1.putAll(hmap1);
    System.out.println("hmap1 is " + hmap1);
 
 

}
}

Can static method access instance variables ?

package com.concretepage;
public class CanStaticMethodAccessInstanceVariables {
static void method1() {
CanStaticMethodAccessInstanceVariables can = new CanStaticMethodAccessInstanceVariables();
can.method2();
}
static void method2() {
System.out.println("Its Correct");
}
}

Arrays as List example

package com.concretepage;
import java.util.Arrays;
import java.util.List;

public class ArraysasList {
public static void main(String[] args) {

String a[] = new String[] {"A", "B", "C", "D"};
List<String> listString = Arrays.asList(a);
    System.out.println(listString);
   
    Integer b[] = new Integer[] {10, 20, 30, 40};
    List<Integer> listInteger = Arrays.asList(b);
    System.out.println(listInteger);
   
    //Long l[] = new Long[] {(long) 100, (long) 200, (long) 300, (long) 400};
    Long l[] = new Long[] {100L, 200L, 300L, 400L};
    List<Long> listLong = Arrays.asList(l);
    System.out.println(listLong);
   

}
}

Arrays.copyOf example

package com.concretepage;
import java.util.Arrays;
public class ArraysCopyOf {
public static void main(String[] args) {
int a[] = new int[] {1, 2, 3};
int b[] = Arrays.copyOf(a, 6);
b[3] = 33;
b[4] = 44;
b[5] = 55;
//b[6] = 66;
for(int j=0; j<b.length; j++) {
System.out.println(b[j]);
}

String s1[] = new String[] {"1","2","3"};

String s2[] = Arrays.copyOf(s1, 6);
s2[3] = "33";
s2[4] = "44";
s2[5] = "55";

for(int k=0; k<s2.length; k++) {
System.out.println(s2[k]);
}






}
}