53 lines
1.6 KiB
Java
53 lines
1.6 KiB
Java
package chapter6;
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import java.util.HashMap;
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import java.util.Iterator;
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import java.util.Map;
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import java.util.Set;
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public class Example15 {
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public static void main(String[] args) {
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HashMap map = new HashMap(); // 创建Map对象
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map.put("2","李四"); //存储键和值
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map.put("3","王五");
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map.put("1","张三");
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// 方法一
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Set keySet = map.keySet(); //获取键的集合
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Iterator it = keySet.iterator();//选代键的集合
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while (it.hasNext()) {
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Object key = it.next();
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Object value = map.get(key); //获取每个键所对应的值
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System.out.println(key + ":" + value);
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}
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Iterator it2 = map.keySet().iterator();
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while (it2.hasNext()) {
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Object key = it2.next();
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System.out.println(key);
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}
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Iterator it3 = map.values().iterator();
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while (it3.hasNext()) {
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Object value = it3.next();
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System.out.println(value);
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}
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// 方法二
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Set entrySet = map.entrySet(); // 获取所有映射关系
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Iterator it4 = entrySet.iterator(); // 获取Iterator对象
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while (it4.hasNext()){
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//获取集合中键值对映射关系
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Map.Entry entry = (Map.Entry) (it4.next());
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Object key = entry.getKey();//获取Entry中的键
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Object value = entry.getValue();//获取Entry中的值
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System.out.println(key + ":" + value);
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}
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for (Object obj : map.entrySet()) {
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System.out.println(obj);
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}
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}
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}
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