看了学习视频，来一段代码
代码语言：javascript复制import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
public class jiheqiantao {
public static void main(String[] args) {
HashMap<String, String> javase = new HashMap<String, String>(); // 基础班
HashMap<String, String> javaee = new HashMap<String, String>(); // 就业班
javase.put("001", "张三");
javase.put("002", "李四");
javaee.put("001", "王五");
javaee.put("002", "赵六");
HashMap<String, HashMap<String, String>> czbk =
new HashMap<String, HashMap<String, String>>();
czbk.put("基础班", javase); // 基础班对应一个HashMap集合
czbk.put("就业班", javaee); // 就业班对应一个HashMap集合
keySet(czbk);
entrySet(czbk);
}
// 利用entrySet遍历，效率比keySet要高
public static void entrySet(HashMap<String, HashMap<String, String>> czbk) {
Set<Map.Entry<String, HashMap<String, String>>> classNameSet =
czbk.entrySet();
Iterator<Map.Entry<String, HashMap<String, String>>> classNameIt =
classNameSet.iterator();
while (classNameIt.hasNext()) {
Map.Entry<String, HashMap<String, String>> classNameEntry =
classNameIt.next();
String classNameKey = classNameEntry.getKey();
HashMap<String, String> classMap = classNameEntry.getValue();
Set<Map.Entry<String, String>> studentSet = classMap.entrySet();
Iterator<Map.Entry<String, String>> studentIt = studentSet.iterator();
while (studentIt.hasNext()) {
Map.Entry<String, String> studentEntry =
studentIt.next();
String numKey = studentEntry.getKey();
String nameValue = studentEntry.getValue();
System.out.println(classNameKey "..." numKey "..." nameValue);
}
}
}
public static void keySet(HashMap<String, HashMap<String, String>> czbk) {
Set<String> classNameSet = czbk.keySet();
Iterator<String> classNameIt = classNameSet.iterator();
while (classNameIt.hasNext()) {
String classNameKey = classNameIt.next();
HashMap<String, String> classMap = czbk.get(classNameKey);
Set<String> studentNum = classMap.keySet();
Iterator<String> studentIt = studentNum.iterator();
while (studentIt.hasNext()) {
String numKey = studentIt.next();
String nameValue = classMap.get(numKey);
System.out.println(classNameKey "..." numKey "..." nameValue);
}
}
}
}
