Set相关知识:
package org.hanqi.array; import java.util.*; public class Test2 { public static void main(String[] args) { // int i;//默认i=0
// int [] m = new int[5];//赋值了5个0 //哈希
Set<String> s = new HashSet<String>();
HashSet<String> s1 = new HashSet<String>(); if(s.add("a"))
{
System.out.println("保存a成功");
}
s.add("b");
s.add("c");
s.add("d");
s.add("e");
s.add("f");
s.add("g"); if(!s.add("a"))
{
System.out.println("保存a失败");
}
//s.add("a");
//s.add("a"); for(String t:s)
{
System.out.print(t);
} System.out.println(); System.out.println("s的size="+s.size()); if(s.remove("d"))
{
System.out.println("移除成功");
}
else
{
System.out.println("移除失败");
} System.out.println("s的size="+s.size()); //迭代器
Iterator<String> it = s.iterator();
while(it.hasNext())
{
String t = it.next();
if(t.equals("c"))
{
it.remove();
}
else
{
System.out.print(t);
} } System.out.println(); System.out.println("s的size="+s.size()); System.out.println("TreeSet"); Set<String> s2 = new TreeSet<String>(); s2.add("f");
s2.add("b");
s2.add("d");
s2.add("c");
s2.add("e");
s2.add("a");
s2.add("g"); for(String t:s2)
{
System.out.print(t);
} System.out.println(); System.out.println("s2的size="+s2.size());
}
}
运行结果为:
Map相关知识:
package org.hanqi.array; import java.util.*; public class Test3 { public static void main(String[] args) { Map<String,String> m = new HashMap<String,String>(); m.put("7", "淄博");
m.put("9", "济南");
m.put("5", "青岛");
m.put("1", "青岛");
m.put("8", "青岛");
m.put("6", "青岛");
m.put("3", "青岛");
m.put("2", "青岛");
m.put("0", "青岛");
//长度
System.out.println("长度="+m.size());
m.put("0534", "青岛");
m.put(null, null);
System.out.println("长度="+m.size());
//根据key获取value
System.out.println("0533="+m.get("0533"));
//key是否存在
if(m.containsKey("0533"))
{
System.out.println("key 0533已存在");
}
//value是否存在
if(m.containsValue("淄博"))
{
System.out.println("value 淄博已存在");
}
//遍历
for(String k:m.keySet())
{
System.out.println(k+"="+m.get(k));
}
}
}
运行结果为:
相关思维导图: