mapdemo.java

JAVA编程思想源代码 值得一下 很难找的

package chapter9;

import java.util.Collection;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
import java.util.Map.Entry;

public class MapDemo {

	public static void main(String[] args) {
		HashMap<String, String> mapHash = new HashMap<String, String>();

		// 使用put方法添加键值对HashMap对象
		mapHash.put("one", "ABC");
		mapHash.put("two", "DEF");
		mapHash.put("three", "GHI");
		mapHash.put("four", "JKL");
		mapHash.put("five", "MNO");
		mapHash.put("six", "PQR");
		mapHash.put("seven", "STU");

		// 使用get方法通过键获取值的方法
		String query = "six";
		System.out.println("the key at  " + query + ".");
		String resultString = (String) mapHash.get(query);
		System.out.println("the value: " + resultString + "\n");

		// 通过keySet方法获取键集合
		Set setKey = mapHash.keySet();
		System.out.println("setKey = " + setKey);
		Collection valueSet = mapHash.values();
		System.out.println("valueSet = " + valueSet);
		// 一次性输出HashMap对象中的所有键值
		Iterator iter = mapHash.keySet().iterator();
		while (iter.hasNext()) {
			String key = (String) iter.next();
			System.out.println("Key " + key + "; Value "
					+ (String) mapHash.get(key));
		}
		// 通过entrySet方法获取Set视图
		Set<Entry<String, String>> hsm = mapHash.entrySet();
		Iterator<Entry<String, String>> i = hsm.iterator();
		for (; i.hasNext();) {
			Entry en = i.next();
			System.out.println("the key is " + en.getKey()
					+ " || the value is " + en.getValue());

		}
		// 使用size方法
		System.out.println("the size is :" + hsm.size());
		System.out.println("the size of the Hashmap is :" + mapHash.size());
	}

}