【java基础增强】增强for循环取Map值

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import static java.lang.System.out;//静态导入import java.util.HashMap;import java.util.Iterator;import java.util.LinkedHashMap;import java.util.List;import java.util.ArrayList;import java.util.Map;import java.util.Map.Entry;import java.util.Set;import org.junit.Test;public class Demo1 {/** * @param args */public static void main(String[] args) {}@Testpublic void test1(){int arr[]={1,2,3,4};for(int i:arr){System.out.print(i+" ");}}@Testpublic void test2(){//传统方式1，通过key取出valueMap mp=new HashMap(); //无序输出mp=new LinkedHashMap(); //正序存入正序输出mp.put("1", "a");mp.put("2", "b");mp.put("3", "c");Set set=mp.keySet();Iterator it=set.iterator();while(it.hasNext()){String key=(String)it.next();String value=(String)mp.get(key);System.out.println(key+"="+value);}}@Testpublic void test3(){//传统方式2，通过 键值对 去取出Map mp=new HashMap(); //无序输出mp=new LinkedHashMap(); //正序存入正序输出mp.put("1", "a");mp.put("2", "b");mp.put("3", "c");Set set=mp.entrySet();Iterator it=set.iterator();while(it.hasNext()){Map.Entry entry=(Entry)it.next();String key=(String) entry.getKey();String value=(String) entry.getValue();System.out.println(key+"="+value);}}@Testpublic void test4(){Map mp=new HashMap(); //无序输出mp=new LinkedHashMap(); //正序存入正序输出mp.put("1", "a");mp.put("2", "b");mp.put("3", "c");//增强for循环取map的第一种方式(Map不能迭代)for(Object obj:mp.keySet()){String key=(String)obj;String value=(String)mp.get(key);System.out.println(key+"="+value);}}@Testpublic void test5(){Map mp=new HashMap(); //无序输出mp=new LinkedHashMap(); //正序存入正序输出mp.put("1", "a");mp.put("2", "b");mp.put("3", "c");//增强for循环取map的第二种方式(Map不能迭代)for(Object obj:mp.entrySet()){Map.Entry entry=(Entry)obj;String key=(String)entry.getKey();String value=(String)entry.getValue();System.out.println(key+"="+value);}}}
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