The following is the specification of useful members of a Java 1.4 (non generic) list handling class useful in developing translators. The closely equivalent C# 1.0 (non-generic) version appears lower on this page.
The later versions of Java and C# introduced generic versions of these classes. For details of how to use these consult this page
import java.util.*;
class ArrayList
// Class for constructing a list of objects
public ArrayList()
// Empty list constructor
public void add(Object o)
// Appends o to end of list
public void add(int index, Object o)
// Inserts o at position index
public Object get(int index)
// Retrieves an object from position index
public Object set(int index, Object o)
// Inserts Object O 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(Object o)
// Returns true if o is in the list
public boolean indexOf(Object o)
// Returns position of o in the list
public Object remove(int index)
// Removes the object at position index
} // ArrayList
Here is a sample program showing the use of this library
import library.*;
import java.util.*;
class ShowArrayList {
// Demonstrate simple application of the non 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 list = new ArrayList(); // 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(((Entry)list.get(i)).name)) // must 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", 61); // 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 = (Entry) list.get(i); // retrieve (via a cast) 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);
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
} // ShowArrayList
The following is the specification of useful members of a C# list handling class useful in developing translators. A closely equivalent Java version appears earlier on this page.
The later versions of Java and C# introduced generic versions of these classes. For details of how to use these consult this page
using System.Collections;
class ArrayList
// Class for constructing a list of objects
public ArrayList()
// Empty list constructor
public int Add(object o)
// Appends o to end of list
public object this [int index] {set; get; }
// Inserts or retrieves an object in position index
// list[index] = object; object = list[index]
public void Clear()
// Clears all elements from list
public int Count { get; }
// Returns number of elements in list
public boolean Contains(object o)
// Returns true if o is in the list
public boolean IndexOf(object o)
// Returns position of o in the list
public void Remove(object o)
// Removes object o from list
public void RemoveAt(int index)
// Removes the object at position index
} // ArrayList
Here is a sample program like the one given earlier showing the use of this library
using Library;
using System.Collections;
using System.Text;
class ShowArrayList {
// Demonstrate simple application of the non-generic ArrayList class in C#
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 list = new ArrayList(); // 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(((Entry)list[i]).name)) // must 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"); // interrogate size of list
Entry patEntry = new Entry("Pat", 61); // 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 = (Entry) list[i]; // retrieve (via a cast) 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[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
} // ShowArrayList
Revised: 2009/10/12