Add more methods to the doubly linked list class then test them • search(e) // Return one node with 3 values (stuID, stuName, stuScore) which matches a given key e (studentID). • addAfter(e, stuID, stuName, stuScore) //Add a new node with 3 values (stuID, stuName, stuScore) after the node with the key e (studentID). • removeAt(e) //Remove a node which matches a given key e (studentID) • count() //Return a number of nodes of list. • update(stuID, stuName, stuScore) //Update the values of one node first code below package DlinkedList; public class DLinkedList { private Node header; private Node trailer; private int size; public DLinkedList() { header = new Node<>(null, null, null); trailer = new Node<>(null, null, null); header.setNext(trailer); trailer.setPrev(header); } public int getSize() { return size; } public boolean isEmpty() { return size==0; } public A getFirstStuID() { return header.getNext().getStuID(); } public B getFirstStuName() { return header.getNext().getStuName(); } public C getFirstStuScore() { return header.getNext().getStuScore(); } public A getLastStuID() { return trailer.getPrev().getStuID(); } public B getLastStuName() { return trailer.getPrev().getStuName(); } public C getLastStuScore() { return trailer.getPrev().getStuScore(); } private void addBetween(A id, B name, C score, Node predecessor, Node successor) { Node newest = new Node<>(id, name, score); newest.setPrev(predecessor); newest.setNext(successor); predecessor.setNext(newest); successor.setPrev(newest); size++; } public void addFirst(A id, B name, C score) { addBetween(id, name,score,header,header.getNext()); } public void addLast(A id, B name, C score) { addBetween(id, name,score, trailer.getPrev(), trailer); } private Node remove(Node node){ Node predecessor = node.getPrev(); Node successor = node.getNext(); predecessor.setNext(successor); successor.setPrev(predecessor); size--; return node; } public Node removeFirst(){ if(isEmpty()) return null; return remove(header.getNext()); } public Node removeLast(){ if(isEmpty()) return null; return remove(trailer.getPrev()); } public Node search(A key){ if(isEmpty()) return null; Node temp = header.getNext(); do{ if(temp.getStuID()== key) return temp; temp = temp.getNext(); }while ( temp != null); return null; } public void addAfter(A key, A id, B name, C score) { if(isEmpty()) return; Node node = search(key); if(node == null) return; addBetween(id, name, score, node, node.getNext()); } public void display() { if(isEmpty()) { System.out.println("Linked list is empty."); return; } Node temp = header.getNext(); do { temp.displayNode(); temp = temp.getNext(); }while(temp.getNext() !=null); } public void addBefore(A key, A id, B name, C score) { if(isEmpty()) return; Node node = search(key); if(node == null) return; addBetween( id, name, score, node.getPrev(), node); } public Node removeAt( A key){ if (isEmpty()) return null; Node node = search(key); if(node == null) return null; return remove(node); } public Node update(A key, A nid, B nname, C nscore){ if(isEmpty()) return null; Node node = search(key); if(node == null) return null; node.setStuID(nid); node.setStuName(nname); node.setStuScore(nscore); return node; } }

Add more methods to the doubly linked list class then test them • search(e) // Return one node with 3 values (stuID, stuName, stuScore) which matches a given key e (studentID). • addAfter(e, stuID, stuName, stuScore) //Add a new node with 3 values (stuID, stuName, stuScore) after the node with the key e (studentID). • removeAt(e) //Remove a node which matches a given key e (studentID) • count() //Return a number of nodes of list. • update(stuID, stuName, stuScore) //Update the values of one node first code below package DlinkedList; public class DLinkedList { private Node header; private Node trailer; private int size; public DLinkedList() { header = new Node<>(null, null, null); trailer = new Node<>(null, null, null); header.setNext(trailer); trailer.setPrev(header); } public int getSize() { return size; } public boolean isEmpty() { return size==0; } public A getFirstStuID() { return header.getNext().getStuID(); } public B getFirstStuName() { return header.getNext().getStuName(); } public C getFirstStuScore() { return header.getNext().getStuScore(); } public A getLastStuID() { return trailer.getPrev().getStuID(); } public B getLastStuName() { return trailer.getPrev().getStuName(); } public C getLastStuScore() { return trailer.getPrev().getStuScore(); } private void addBetween(A id, B name, C score, Node predecessor, Node successor) { Node newest = new Node<>(id, name, score); newest.setPrev(predecessor); newest.setNext(successor); predecessor.setNext(newest); successor.setPrev(newest); size++; } public void addFirst(A id, B name, C score) { addBetween(id, name,score,header,header.getNext()); } public void addLast(A id, B name, C score) { addBetween(id, name,score, trailer.getPrev(), trailer); } private Node remove(Node node){ Node predecessor = node.getPrev(); Node successor = node.getNext(); predecessor.setNext(successor); successor.setPrev(predecessor); size--; return node; } public Node removeFirst(){ if(isEmpty()) return null; return remove(header.getNext()); } public Node removeLast(){ if(isEmpty()) return null; return remove(trailer.getPrev()); } public Node search(A key){ if(isEmpty()) return null; Node temp = header.getNext(); do{ if(temp.getStuID()== key) return temp; temp = temp.getNext(); }while ( temp != null); return null; } public void addAfter(A key, A id, B name, C score) { if(isEmpty()) return; Node node = search(key); if(node == null) return; addBetween(id, name, score, node, node.getNext()); } public void display() { if(isEmpty()) { System.out.println("Linked list is empty."); return; } Node temp = header.getNext(); do { temp.displayNode(); temp = temp.getNext(); }while(temp.getNext() !=null); } public void addBefore(A key, A id, B name, C score) { if(isEmpty()) return; Node node = search(key); if(node == null) return; addBetween( id, name, score, node.getPrev(), node); } public Node removeAt( A key){ if (isEmpty()) return null; Node node = search(key); if(node == null) return null; return remove(node); } public Node update(A key, A nid, B nname, C nscore){ if(isEmpty()) return null; Node node = search(key); if(node == null) return null; node.setStuID(nid); node.setStuName(nname); node.setStuScore(nscore); return node; } }

Database System Concepts

7th Edition

ISBN:9780078022159

Author:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Publisher:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Chapter1: Introduction

Section: Chapter Questions

Problem 1PE

See similar textbooks

Related questions

Question

first code below

package DlinkedList;
public class DLinkedList<A,B,C> {
private Node<A,B,C> header;
private Node<A,B,C> trailer;
private int size;

public DLinkedList() {
header = new Node<>(null, null, null);
trailer = new Node<>(null, null, null);
header.setNext(trailer);
trailer.setPrev(header);

}
public int getSize() {
return size;
}
public boolean isEmpty() {
return size==0;
}
public A getFirstStuID() {
return header.getNext().getStuID();
}
public B getFirstStuName() {
return header.getNext().getStuName();
}
public C getFirstStuScore() {
return header.getNext().getStuScore();

}

public A getLastStuID() {
return trailer.getPrev().getStuID();
}
public B getLastStuName() {
return trailer.getPrev().getStuName();
}
public C getLastStuScore() {
return trailer.getPrev().getStuScore();
}

private void addBetween(A id, B name, C score, Node<A,B,C> predecessor, Node<A,B,C> successor) {
Node<A,B,C> newest = new Node<>(id, name, score);
newest.setPrev(predecessor);
newest.setNext(successor);
predecessor.setNext(newest);
successor.setPrev(newest);
size++;
}
public void addFirst(A id, B name, C score) {
addBetween(id, name,score,header,header.getNext());
}
public void addLast(A id, B name, C score) {
addBetween(id, name,score, trailer.getPrev(), trailer);
}
private Node<A,B,C> remove(Node<A,B,C> node){
Node<A,B,C> predecessor = node.getPrev();
Node<A,B,C> successor = node.getNext();
predecessor.setNext(successor);
successor.setPrev(predecessor);
size--;
return node;
}
public Node<A,B,C> removeFirst(){
if(isEmpty())
return null;
return remove(header.getNext());
}
public Node<A,B,C> removeLast(){
if(isEmpty())
return null;
return remove(trailer.getPrev());
}
public Node<A,B,C> search(A key){
if(isEmpty())
return null;
Node<A,B,C> temp = header.getNext();
do{
if(temp.getStuID()== key)
return temp;
temp = temp.getNext();
}while ( temp != null);
return null;
}

public void addAfter(A key, A id, B name, C score) {
if(isEmpty())
return;
Node<A,B,C> node = search(key);
if(node == null)
return;
addBetween(id, name, score, node, node.getNext());
}

public void display() {
if(isEmpty()) {
System.out.println("Linked list is empty.");
return;
}
Node<A,B,C> temp = header.getNext();
do {
temp.displayNode();
temp = temp.getNext();
}while(temp.getNext() !=null);
}
public void addBefore(A key, A id, B name, C score) {
if(isEmpty())
return;
Node<A,B,C> node = search(key);
if(node == null)
return;
addBetween( id, name, score, node.getPrev(), node);
}
public Node<A,B,C> removeAt( A key){
if (isEmpty())
return null;
Node<A,B,C> node = search(key);
if(node == null)
return null;
return remove(node);
}
public Node<A,B,C> update(A key, A nid, B nname, C nscore){
if(isEmpty())
return null;
Node<A,B,C> node = search(key);
if(node == null)
return null;
node.setStuID(nid);
node.setStuName(nname);
node.setStuScore(nscore);
return node;
}
}

The image contains Java code for a class named `TwistyPasta`. The code appears to be designed to output text, displayed using the `System.out.println()` method, and involves a series of nested loops.

```java
package twistypasta;

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

// First loop
for (int i = 1; i <= 5; i++) {
System.out.print("*");
System.out.print("#");
System.out.print("!");
System.out.print("@");
System.out.print(">");
System.out.print("<");
System.out.print(".");
System.out.print("/");
System.out.println("\\");
}

// Second loop
while (true) {
System.out.print("$");
System.out.println("%");
try {
Thread.sleep(1000); // Pauses for 1 second
} catch (InterruptedException e) {}
}

// Third loop
for (int i = 0; i < 5; i++) {
System.out.println("Twist");
}

// Fourth loop
String[] array = {"A", "B", "C"};
for (String s : array) {
System.out.print(s);
System.out.println("Loop");
}

}
}
```

### Explanation of Code Structure:

1. **Package Declaration:**
- `package twistypasta;` indicates that this class belongs to the `twistypasta` package.

2. **Class Definition:**
- `public class TwistyPasta {}` defines a public class named `TwistyPasta`.

3. **Main Method:**
- The entry point of the program is `public static void main(String[] args) {}`.

4. **First Loop:**
- A `for` loop runs five times, printing a sequence of symbols (`*`, `#`, `!`, `@`, `>`, `<`, `.`, `/`, `\`) each time.

5. **Second Loop:**
- An infinite `while` loop continuously prints `$` followed by `%` with a one-second pause between iterations using `Thread.sleep(1000)`.

6. **Third Loop:**
- A `for` loop prints the word "Twist" five times.

7. **Fourth Loop:**
- A `for-each`

The image shows a Java class definition for a generic linked list node, which uses three generic parameters: A, B, and C. The class is named `Node<A, B, C>`. Below is a transcription and explanation of the code:

### Code Explanation

- **Class Definition:**
```java
class Node<A, B, C> {
```

- **Private Variables:**
- `stuID`: of type `A`, storing the ID.
- `stuName`: of type `B`, storing the name.
- `stuScore`: of type `C`, storing the score.
- `next`: a reference to the next node.
- `prev`: a reference to the previous node.

```java
private A stuID;
private B stuName;
private C stuScore;
private Node<A, B, C> next;
private Node<A, B, C> prev;
```

- **Constructor:**
Initializes a node with given ID, name, and score. Sets `next` and `prev` to null initially.

```java
public Node(A id, B name, C score) {
stuID = id;
stuName = name;
stuScore = score;
next = null;
prev = null;
}
```

- **Getters:**
Methods to get the values of `stuID`, `stuName`, `stuScore`, `next`, and `prev`.

```java
public A getStuID() {
return stuID;
}

public B getStuName() {
return stuName;
}

public C getStuScore() {
return stuScore;
}

public Node<A, B, C> getNext() {
return next;
}

public Node<A, B, C> getPrev() {
return prev;
}
```

- **Setters:**
Methods to set the values of `stuID`, `stuName`, `stuScore`, `next`, and `prev`.

```java
public void setStuID(A ID) {
stuID = ID;
}

public void setStuName(B name) {
stuName = name;
}

public void setStuScore(C score) {
stuScore = score;
}

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