Java学习 集合 部分作业01

package work01;
/*
 * (1)定义一个学生类Student，包含属性：姓名(String name)、年龄(int age)
	(2)定义Map集合，用Student对象作为key，用字符串(此表示表示学生的住址)作为value
	(3)利用四种方式遍历Map集合中的内容，格式：key::value
 */
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;

public class WORK01 {
	public static void main(String[] args) {
		HashMap<Student, String> studentHashMap = new HashMap<>();
		studentHashMap.put(new Student("张华", 16), "吉林省长春市");
		studentHashMap.put(new Student("李明", 15), "吉林省四平市");
		studentHashMap.put(new Student("王鹏", 17), "吉林省延吉市");
		studentHashMap.put(new Student("赵云", 16), "吉林省松原市");
		
		//function01(studentHashMap);
		//function02(studentHashMap);
		//function03(studentHashMap);
		function04(studentHashMap);
	}
	
	//遍历方法1  keySet+iterator
	public static void function01(HashMap<Student, String> student){
		Set<Student> studentSet = student.keySet();
		
		Iterator<Student> studentit = studentSet.iterator();
		while(studentit.hasNext()){
			Student key = studentit.next();
			String value = student.get(key);
			System.out.println(key+" "+value);
		}
	}
	//遍历方法2 entrySet+iterator
	public static void function02(HashMap<Student, String> student){
		Set<Map.Entry<Student, String>> studentSet = student.entrySet();
		
		Iterator<Map.Entry<Student, String>> studentIt = studentSet.iterator();
		
		while(studentIt.hasNext()){
			Map.Entry<Student, String> studentEntry = studentIt.next();
			System.out.println(studentEntry.getKey()+"::"+studentEntry.getValue());
		}
	}
	// 增强for entry
	public static void function03(HashMap<Student, String> student){
		for(Map.Entry<Student, String> entry : student.entrySet()){
			System.out.println(entry.getKey()+"::"+entry.getValue());
		}
	}
	
	//增强for keySet
	public static void function04(HashMap<Student, String> student){
		for(Student key : student.keySet()){
			String value = student.get(key);
			System.out.println(key+"::"+value);
		}
	}

}

package work02;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.Scanner;

/*
 *  (1)利用键盘录入，输入一个字符串
	(2)统计该字符串中各个字符的数量
	(3)如：
		用户输入字符串"If~you-want~to~change-your_fate_I_think~you~must~come-to-the-dark-horse-to-learn-java"
		程序输出结果：-(9)I(2)_(3)a(7)c(2)d(1)e(6)f(2)g(1)h(4)i(1)j(1)k(2)l(1)m(2)n(4)o(8)r(4)s(2)t(8)u(4)v(1)w(1)y(3)~(6)

 */
public class Work02 {
	public static void main(String[] args) {
		System.out.println("请输入字符串:");
		Scanner sc = new Scanner(System.in);
		String str = sc.nextLine();
		ArrayList<String> array = new ArrayList<>();
		HashMap<Object, Integer> arrHashMap = new HashMap<>();
		//将输入加入到arraylist集合中
		array.add(str);
		//统计并把统计存储到 arrHashMap 中
		count(array,arrHashMap);
		//遍历 hashmap 打印出来
		charNum(arrHashMap);
	}
	

	//统计字符的 方法 count
	public static void count(ArrayList<String> str ,HashMap<Object, Integer> arrHashMap){
		char[] ch = str.toString().toCharArray();
		int[] num = new int[ch.length];
		
		for(int i = 1 ; i < ch.length-1 ; i++){
			int count = 1;
			for(int j = 1 ; j < ch.length-1 ; j++){
				if(ch[i] == ch[j]){
					num[i] = count++;
				}
			}
		}
		
		for(int i = 1 ; i < num.length-1 ; i++){
			arrHashMap.put(ch[i], num[i]);
		}
	}
	//打印输出
	private static void charNum(HashMap<Object, Integer> arrHashMap) {
		Object[] key_arr = arrHashMap.keySet().toArray();
		Arrays.sort(key_arr);
		for(Object key : key_arr){
			Object skey = key;
			System.out.print(skey+"("+arrHashMap.get(skey)+") ");
		}
	}
	

}