Student 類別, HashSet 找值, TreeSet 排序找值, LinkedList 排序找值, ArrayList 排序找值

ArrayList.java

package Test01;

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;

public class StudentArrayList {
	public static void main(String[] args) throws IOException {
		String FileName = "test0616.txt";
		FileReader fr = new FileReader(FileName);
		BufferedReader br = new BufferedReader(fr);

		ArrayList<Student> al = new ArrayList<Student>();
		String inputStr;
		while ((inputStr = br.readLine())!=null){
			String[] tmp = inputStr.split(",");
			Student stu = new Student(Integer.parseInt(tmp[0]), tmp[1], Integer.parseInt(tmp[2]), Float.parseFloat(tmp[3]));
			al.add(stu);
		}

		// 使用覆載 comparable 的 compareTo
		Collections.sort(al);
		// 使用覆載 comparator 的 compare
		Collections.sort(al, new Student()); // Student implements comparator
		
		System.out.println("ArrayListList:");
		for (Object obj : al.toArray()){
			Student s=(Student)obj;
			System.out.printf("號碼:%-8d 姓名:%-8s 身高:%-4d 體重:%-3.2f\n",s.getNum(), s.getName(), s.getHeight(), s.getWeight());
		}

		System.out.println("身高最高:");
		System.out.println("姓名: " + al.get(al.size()-1).getName() + " 身高: " + al.get(al.size()-1).getHeight());
		System.out.println("身高最矮: ");
		System.out.println("姓名: " + al.get(0).getName() + " 身高: " + al.get(0).getHeight());

	}
}

HashSet.java

package Test01;

import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.util.Collections;
import java.util.HashSet;
import java.util.Iterator;

public class StudentHashSet {
	public static void main(String[] args) throws IOException{
		String FileName = "test0616.txt";
		FileReader fr = new FileReader(FileName);
		BufferedReader br = new BufferedReader(fr);

		HashSet<Student> hs = new HashSet<Student>();
		String inputStr;
		while ((inputStr=br.readLine())!=null){
			String[] tmp = inputStr.split(",");
			Student stu = new Student(Integer.parseInt(tmp[0]), tmp[1], Integer.parseInt(tmp[2]), Float.parseFloat(tmp[3]));
			// HashSet 本身有無序的特性
			hs.add(stu);
		}
		
		// 利用 Iterator 將 HashSet 裡的資料一個一個讀出來
		Iterator<Student> it1 = hs.iterator();
		Student highSt = getHighest(it1);
		// 讀取 Iterator 不可倒退，且讀完即失效，所以使用了第二個來存取最小值
		Iterator<Student> it2 = hs.iterator();
		Student shortSt = getShortest(it2);
		
		System.out.println("HashSet:");
		for (Object obj : hs.toArray()){
			Student s=(Student)obj;
			System.out.printf("號碼:%-8d 姓名:%-8s 身高:%-4d 體重:%-3.2f\n",s.getNum(), s.getName(), s.getHeight(), s.getWeight());
		}
		System.out.println("身高最高:");
		System.out.println("姓名: " + highSt.getName() + " 身高: " + highSt.getHeight());
		System.out.println("身高最矮: ");
		System.out.println("姓名: " + shortSt.getName() + " 身高: " + shortSt.getHeight());
	}
	
	// 循序比對每一個人的身高
	public static Student getHighest(Iterator<Student> it){
		Student st = it.next();
		while(it.hasNext()){
			Student stmp=it.next();
			if (st.getHeight() < stmp.getHeight())
				st = stmp;
		}
		return st;	// 回傳身高最高的人
	}
	
	// .. 同上
	public static Student getShortest(Iterator<Student> it){
		Student st = it.next();
		while(it.hasNext()){
			Student stmp=it.next();
			if (st.getHeight() > stmp.getHeight())
				st = stmp;
		}
		return st;	// 回傳身高最高的人
	}
}

LinkedList.java

package Test01;

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.util.Collections;
import java.util.LinkedList;

public class StudentLinkedList {
	public static void main(String[] args) throws IOException {
		String FileName = "test0616.txt";
		FileReader fr = new FileReader(FileName);
		BufferedReader br = new BufferedReader(fr);

		LinkedList<Student> ls = new LinkedList<Student>();
		String inputStr;
		while ((inputStr = br.readLine())!=null){
			String[] tmp = inputStr.split(",");
			Student stu = new Student(Integer.parseInt(tmp[0]), tmp[1], Integer.parseInt(tmp[2]), Float.parseFloat(tmp[3]));
			ls.add(stu);
		}
		
		// 使用覆載 comparable 的 compareTo
		Collections.sort(ls);
		// 使用覆載 comparator 的 compare
		Collections.sort(ls, new Student());
		
		System.out.println("LinkedList:");
		for (Object obj : ls.toArray()){
			Student s=(Student)obj;
			System.out.printf("號碼:%-8d 姓名:%-8s 身高:%-4d 體重:%-3.2f\n",s.getNum(), s.getName(), s.getHeight(), s.getWeight());
		}
		System.out.println("身高最高:");
		System.out.println("姓名: " + ls.getLast().getName() + " 身高: " + ls.getLast().getHeight());
		System.out.println("身高最矮: ");
		System.out.println("姓名: " + ls.getFirst().getName() + " 身高: " + ls.getFirst().getHeight());
	}
}

Student.java

package Test01;

import java.util.Comparator;

public class Student implements Comparable<Student>, Comparator<Student>{
	private int num;
	private String name;
	private int height;
	private float weight;
	
	public Student(){
		// nothing
	}
	
	// overloading constructor
	public Student(int n, String na, int h, float w){
		setNum(n);
		setName(na);
		setHeight(h);
		setWeight(w);
	}
	public int getNum() {
		return num;
	}
	public void setNum(int num) {
		this.num = num;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public int getHeight() {
		return height;
	}
	public void setHeight(int height) {
		this.height = height;
	}
	public float getWeight() {
		return weight;
	}
	public void setWeight(float weight) {
		this.weight = weight;
	}

	@Override
	public int compareTo(Student st) {
		// 若回傳值<0，新的 Element 會加在後方，因此透過比較決定擺放位置
		// eg. 小至大
		return this.height-st.getHeight();
	}
	
	@Override
	public int compare(Student s1, Student s2) {
		// 反之則是大至小
		return -s1.compareTo(s2);
	}
	
}

TreeSet.java

package Test01;

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.util.TreeSet;

public class StudentTreeSet {
	public static void main(String[] args) throws IOException {
		String FileName = "test0616.txt";
		FileReader fr = new FileReader(FileName);
		BufferedReader br = new BufferedReader(fr);

		// TreeSet 為實作 SortedSet(interface) 的類別，預設有基本資料型別的排序方法
		// 但未知型別物件的排序需要自行定義，使Student覆寫compareTo方法讓TreeSet集合能夠使用
		TreeSet<Student> ts = new TreeSet<Student>();

//		// 透過 TreeSet 建構子指定使用 compare 方法 ----- TreeSet建構子會尋找類別裡的compare(obj1,obj2)方法
//		TreeSet<Student> ts = new TreeSet<Student>(new Student());
				
		String inputStr;
		while ((inputStr=br.readLine())!=null){
			String[] tmp = inputStr.split(",");
			Student stu = new Student(Integer.parseInt(tmp[0]), tmp[1], Integer.parseInt(tmp[2]), Float.parseFloat(tmp[3]));
			// TreeSet 在加入時會參照 compareTo 方法排序
			ts.add(stu);
		}

		System.out.println("TreeSet:");
		for (Object obj : ts.toArray()){
			Student s=(Student)obj;
			System.out.printf("號碼:%-8d 姓名:%-8s 身高:%-4d 體重:%-3.2f\n",s.getNum(), s.getName(), s.getHeight(), s.getWeight());
		}
		System.out.println("身高最高:");
		System.out.println("Name: "+((Student)ts.last()).getName() + " Height: "+((Student)ts.last()).getHeight());
		System.out.println("身高最矮:");
		System.out.println("Name: "+((Student)ts.first()).getName() + " Height: "+((Student)ts.first()).getHeight());
	}

}