The following is the specification of useful members of a Java (generic) list handling class useful in developing translators. The closely equivalent C# (generic) version appears lower on this page.
The earlier versions of Java and C# did not have generic versions of these classes, but worked with elements of the Object class, which necessitated casting operations. For details of how to use these consult this page.
import java.util.*;
class ArrayList<E>
// Class for constructing a list of elements of type E in Java
public ArrayList<E>()
// Empty list constructor
public void add(E element)
// Appends element to end of list
public void add(int index, E element)
// Inserts element at position index
public E get(int index)
// Retrieves an element from position index
public E set(int index, E element)
// Inserts element into the list at position index
public void clear()
// Clears all elements from list
public int size()
// Returns number of elements in list
public boolean isEmpty()
// Returns true if list is empty
public boolean contains(E element)
// Returns true if element is in the list
public boolean indexOf(E element)
// Returns position of element in the list
public E remove(int index)
// Removes the element at position index
public E remove(E element)
// Removes element from the list
} // ArrayList
Here is a sample program showing the use of this library
import library.*;
import java.util.*;
class ShowGenericList {
// Demonstrate simple application of the generic ArrayList class in Java
static class Entry {
public String name;
public int age; // other fields could be added
public Entry(String name, int age) { // constructor
this.name = name;
this.age = age;
}
} // Entry
static ArrayList<Entry> list = new ArrayList<Entry>(); // global for simplicity here!
public static int position(String name) {
// Finds position of entry with search key name in list, or -1 if not found
int i = list.size() - 1; // index of last entry
while (i >= 0 && // short-circuit protection
!name.equals(list.get(i).name)) // no need to cast before extracting field
i--; // will reach -1 if no match
return i;
} // position
public static void main (String[] args) {
// Build a list of people's names and ages
IO.writeLine("Supply a list of people's names and ages. CTRL-Z to terminate");
do {
String name = IO.readWord();
if (IO.eof()) break;
int age = IO.readInt();
IO.readLn();
list.add(new Entry(name, age)); // add to end of list
} while (!IO.eof());
IO.writeLine(list.size() + " items stored"); // report size of list
Entry patEntry = new Entry("Pat", 63); // that fellow again!
list.set(0, patEntry); // insert him on position 0
StringBuffer sb = new StringBuffer(); // demonstrate StringBuffer use
for (int i = 0; i < list.size(); i++) { // display each entry
Entry e = list.get(i); // retrieve an item at position i
IO.write(e.name, -16); IO.writeLine(e.age); // -16 means "left justify"
sb.append(e.name + " "); // add the names to a StringBuffer object
}
IO.writeLine();
int where = position("Peter"); // find the silly fellow!
if (where < 0) IO.writeLine("Peter not found");
else {
Entry peter = (Entry) list.get(where); // retrieve an item at position where
IO.writeLine("Peter found at position " + where + ". He is " + peter.age + " years old");
}
if (sb.length() > 0) {
IO.writeLine();
IO.writeLine("Summary of names:");
IO.writeLine();
IO.writeLine(sb.toString());
}
} // main
} // ShowGenericList
The following is the specification of useful members of a C# 2.0 generic list handling class useful in developing translators. A closely equivalent Java version appears earlier on this page. Note that this class is called List and not ArrayList.
The earlier versions of Java and C# did not have generic versions of these classes, but worked with elements of the Object class, which necessitated casting operations. For details of how to use these consult this page.
using System.Collections.Generic;
class List<E>
// Class for constructing a list of elements of type E in C#
public List<E>()
// Empty list constructor
public void Add(E element)
// Appends element to end of list
public void Insert(int index, E element)
// Inserts element at position index
public object this [int index] {set; get; }
// Inserts or retrieves an element at position index
// list[index] = element; element = list[index];
public void Clear()
// Clears all elements from list
public int Count { get; }
// Returns number of elements in list
public boolean Contains(E element)
// Returns true if element is in the list
public boolean IndexOf(E element)
// Returns position of element in the list
public void RemoveAt(int index)
// Removes the element at position index
public void Remove(E element)
// Removes element from list
} // List
Here is a sample program like the one given earlier showing the use of this library
using Library;
using System.Collections.Generic;
using System.Text;
class ShowGenericList {
// Demonstrate simple application of the generic List class (C# version 2.0)
class Entry {
public string name;
public int age; // other fields could be added
public Entry(string name, int age) { // constructor
this.name = name;
this.age = age;
}
} // Entry
static List<Entry> list = new List<Entry>(); // global for simplicity here!
public static int Position(string name) {
// Finds position of entry with search key name in list, or -1 if not found
int i = list.Count - 1; // index of last entry
while (i >= 0 && // short-circuit protection
!name.Equals(list[i].name)) // no need to cast before extracting field
i--; // will reach -1 if no match
return i;
} // Position
public static void Main (string[] args) {
// Build a list of people's names and ages
IO.WriteLine("Supply a list of people's names and ages. CTRL-Z to terminate");
do {
string name = IO.ReadWord();
if (IO.EOF()) break;
int age = IO.ReadInt();
IO.ReadLn();
list.Add(new Entry(name, age)); // add to end of list
} while (!IO.EOF());
IO.WriteLine(list.Count + " items stored"); // report size of list
Entry patEntry = new Entry("Pat", 63); // that fellow again!
list[0] = patEntry; // insert him on position 0
StringBuilder sb = new StringBuilder(); // demonstrate StringBuilder use
for (int i = 0; i < list.Count; i++) { // display each entry
Entry e = list[i]; // retrieve an item at position i
IO.Write(e.name, -16); IO.WriteLine(e.age); // -16 means "left justify"
sb.Append(e.name + " "); // add the names to a StringBuffer object
}
IO.WriteLine();
int where = Position("Peter"); // find the silly fellow!
if (where < 0) IO.WriteLine("Peter not found");
else {
Entry peter = list[where]; // retrieve an item at position where
IO.WriteLine("Peter found at position " + where + ". He is " + peter.age + " years old");
}
if (sb.Length > 0) {
IO.WriteLine();
IO.WriteLine("Summary of names:");
IO.WriteLine();
IO.WriteLine(sb.ToString());
}
} // Main
} // ShowGenericList
Revised: 2014/03/13