genericstester.java

基于netbeans的java桌面应用程序合集

package com.sun.tiger.generic;

import java.io.IOException;
import java.io.PrintStream;
import java.util.HashMap;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;

public class GenericsTester {

  public GenericsTester() {
  }

  private List<String> getListOfStrings() {
    List<String> list = new LinkedList<String>();
    list.add("Hello");
    list.add("World");
    list.add("How");
    list.add("Are");
    list.add("You?");

    return list;
  }
  
  public void testTypeSafeLists(PrintStream out) throws IOException {
    List<String> listOfStrings = getListOfStrings();
    for (Iterator<String> i = listOfStrings.iterator(); i.hasNext(); ) {

//      String item = i.next();
 
      // Work with that string
    }
//
//    List<String> onlyStrings = new LinkedList<String>();
//    onlyStrings.add("Legal addition");
 
//    listOfStrings.add(new StringBuilder("Illegal Addition"));
//    listOfStrings.add(25);

  }
  
  
  public void testTypeSafeMaps(PrintStream out) throws IOException {
    Map<Integer, Integer> squares = new HashMap<Integer, Integer>();

    for (int i=0; i<100; i++) {
      squares.put(i, i*i);
    }

    for (int i=0; i<10; i++) {
      int n = i*3;
      out.println("The square of " + n + " is " + squares.get(n));
    }
  }
  

  public void testTypeSafeIterators(PrintStream out) throws IOException {
    List<String> listOfStrings = new LinkedList<String>();
    listOfStrings.add("Happy");
    listOfStrings.add("Birthday");
    listOfStrings.add("To");
    listOfStrings.add("You");
  /*
     for (Iterator i = listOfStrings.iterator(); i.hasNext(); ) {
      String s = (String) i.next();
      out.println(s);
    }
 */ 
    for (Iterator<String> i = listOfStrings.iterator(); i.hasNext(); ) {
      String s = i.next();
      out.println(s);
    }

    printListOfStrings(getListOfStrings(), out);
  }

  private List getList() {
    List list = new LinkedList();
    list.add(3);
    list.add("Blind");
    list.add("Mice");

    return list;
  }



  public void testTypeSafeReturnValues(PrintStream out) throws IOException {
    List<String> strings = getListOfStrings();
 
    for (String s : strings) {
      out.println(s);
    }
  }

    private void printListOfStrings(List<String> list, PrintStream out)
    throws IOException {

    for (Iterator<String> i = list.iterator(); i.hasNext(); ) {
      out.println(i.next());
    }
  }

  public void printList(List<?> list, PrintStream out) throws IOException {
    for (Iterator<?> i = list.iterator(); i.hasNext(); ) {
      out.println(i.next().toString());
    }
  }

  public static void main(String[] args) {
    GenericsTester tester = new GenericsTester();

    try {
      tester.testTypeSafeLists(System.out);
//      tester.testTypeSafeMaps(System.out);
/*      tester.testTypeSafeIterators(System.out);
      tester.testTypeSafeReturnValues(System.out);

      List<Integer> ints = new LinkedList<Integer>();
      ints.add(1);
      ints.add(2);
      ints.add(3);
      tester.printList(ints, System.out);
*/
      /** Uncomment for an error
      NumberBox<String> illegal = new NumberBox<String>();
       */
    } catch (Exception e) {
      e.printStackTrace();
    }
  }
}