Theprogrammersfirst: February 2017

2017-02-15

Understanding Java bytecode

Java bytecode

Java bytecode is the instruction set of the Java virtual machine. Each bytecode is composed of one, or in some cases two bytes that represent the instruction (opcode), along with zero or more bytes for passing parameters. Of the 255 possible byte-long opcodes, as of 2015, 198 are in use (~78%), 54 are reserved for future use (~21%), and 3 instructions (~1%) are set aside as permanently unimplemented.

The Java bytecode system does not directly support floating point operations beyond 32 bits, except indirectly via bytecodes that enable use of 64-bit and 80-bit intermediate IEEE floating point operations.

Java machine level language

outer:
for (int i = 2; i < 1000; i++) {
    for (int j = 2; j < i; j++) {
        if (i % j == 0)
            continue outer;
    }
    System.out.println (i);
}

A Java compiler might translate the Java code above into byte code as follows, assuming the above was put in a method:

0:   iconst_2
1:   istore_1
2:   iload_1
3:   sipush  1000
6:   if_icmpge       44
9:   iconst_2
10:  istore_2

JDK

The Java Development Kit (JDK) is a software development environment used for developing Java applications. It contains JRE development tools.

JRE

Java Runtime Environment (JRE) is a software package that contains what is required to run a Java program. It includes a Java Virtual Machine implementation together with an implementation of the Java Class Library.

JVM

Java virtual machine (JVM) is an abstract computing machine that enables a computer to run a Java program. It converts Java byte code into machine language and executes it.

2017-02-10

Tree traversal and height and depth Implementation

package DataStructure3;

import java.util.ArrayList;
import java.util.LinkedList;

class Node<E> {
E data;
LinkedList<Node> next;
int lebel;
}

public class TestTree {

public static void main(String[] args) {

Node root = new Node();
root.data = 1;
root.lebel=1;

root = add(root, 1, 2);
root = add(root, 1, 3);
root = add(root, 1, 4);
root = add(root, 1, 5);
root = add(root, 2, 6);
root = add(root, 3, 7);
root = add(root, 4, 8);
root = add(root, 5, 9);
root = add(root, 5, 10);
root = add(root, 6, 11);
root = add(root, 7, 12);
root = add(root, 13, 1);

Tree with N child Java implementation

K- tree Implementation in java
Tree Pre-order traversal

package DataStructure3;
import java.util.LinkedList;
class Node<E> {
E data;
LinkedList<Node> next;
}
public class TestTree {
public static void main(String[] args) {
// TODO Auto-generated method stub
/*
* Node head=new Node(); head.data=1;
*
* Node c1=new Node(); c1.data=2;
*
* Node c2=new Node(); c2.data=21; LinkedList l=new LinkedList();
* l.add(c1); l.add(c2); head.next=l;
*
* LinkedList l2=new LinkedList(); Node c3=new Node(); c3.data=3;
* l2.add(c3);

Background image Problem

Solution for background Image problems in
Apple Mail 9
Outlook 2000
Outlook 2002
Outlook 2003
Outlook 2007
Outlook 2010
Outlook 2011
Outlook 2013
Outlook 2016
Thunderbird 45
Android 4.4
Gmail App
Gmail App
iPhone 5
iPhone 5s
iPhone 6
iPhone 6s
iPhone 6s Plus
iPad (Retina)
iPad Mini
AOL Mail
G Suite
Gmail
Office 365
Outlook.com
Yahoo! Mail

Tree with One child - Implementation in Java

class Node {
String name;
Node child;
}

public class TreeTest {
static Node add(Node x, String child) {
if (x == null) {
Node node = new Node();
node.name = child;
x=node;
return x;
}
if (x.child != null) {
add(x.child, child);
}
else{
Node node = new Node();
node.name = child;
x.child=node;
}
return x;
}

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