J2SE之容器_Map 介面_泛型

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Map 介面

Map方法舉例

import java.util.*;public class TestMap2 {  public static void main(String args[]) {    Map<String, Integer> m1 = new HashMap<String , Integer>();     m1.put("one", 1);    m1.put("two", 2);    m1.put("three", 3);    System.out.println(m1.size());    System.out.println(m1.containsKey("one"));    if(m1.containsKey("two")) {      //int i = ((Integer)m1.get("two")).intValue();      int i = m1.get("two");      System.out.println(i);    }  }}

TestMap2.java

import java.util.*;public class TestArgsWords {  //private static final Integer ONE = new Integer(1);  private static final int ONE = 1;  public static void main(String args[]) {    Map m = new HashMap();    for (int i = 0; i < args.length; i++) {      //Integer freq = (Integer) m.get(args[i]);            int freq = (Integer) m.get(args[i]) == null ? 0 : (Integer) m.get(args[i]);      //m.put(args[i],(freq == null? ONE : new Integer(freq.intValue() + 1)));      m.put(args[i], freq==0 ? ONE : freq + 1);    }    System.out.println        (m.size() + " distinct words detected:");    System.out.println(m);  }}

TestArgsWords JDK1.5泛型

import java.util.*;public class BasicGeneric {    public static void main(String[] args) {        List<String> c = new ArrayList<String>();        c.add("aaa");        c.add("bbb");        c.add("ccc");        for(int i=0; i<c.size(); i++) {            String s = c.get(i);            System.out.println(s);        }                Collection<String> c2 = new HashSet<String>();        c2.add("aaa"); c2.add("bbb"); c2.add("ccc");        for(Iterator<String> it = c2.iterator(); it.hasNext(); ) {            String s = it.next();            System.out.println(s);        }    }}class MyName implements Comparable<MyName> {    int age;        public int compareTo(MyName mn) {        if(this.age > mn.age) return 1;        else if(this.age < mn.age) return -1;        else return 0;    }}

BasicGeneric.java

import java.util.*;public class TestArgsWords2 {  private static final int ONE = 1;  public static void main(String args[]) {    Map<String, Integer> m = new HashMap<String, Integer>();    for (int i = 0; i < args.length; i++) {            if(!m.containsKey(args[i])) {          m.put(args[i], ONE);      }      else {          int freq = m.get(args[i]);          m.put(args[i], freq + 1);      }          }    System.out.println        (m.size() + " distinct words detected:");    System.out.println(m);  }}

TestArgsWords2.java總結

 

J2SE之容器_Map 介面_泛型