JavaSE 进阶 (6) 集合

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public class MySet1 {
	public static void main(string[] args) {
		Set<String> set = new TreeSet();
		set.add("aaa");
		set.add("aaa");
		set.add("bbb");
		set.add("ccc");
	
		//for(int i = 0; i < set.size(); i++){
		//	//Set集合是没有索引的，所以不能使用通过索引获取元素的方法
		//}			
			

		Iterator<string> it = set.iterator();
		while(it.hasNext()){
			String s = it.next();
			System.out.println(s);  //aaa  bbb  ccc
		}
		//---------------------------------------------------
		for (String s : set){
			System.out.println(s);  //aaa  bbb  ccc
		}
	}
}

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public class MySet1 {
	public static void main(string[] args) {
		Set<String> set = new TreeSet();
		set.add("ccc");
		set.add("aaa");
		set.add("aaa");
		set.add("bbb");
		
		Iterator<string> it = set.iterator();
		while(it.hasNext()){
			String s = it.next();
			System.out.println(s);  //aaa  bbb  ccc
		}
		//---------------------------------------------------
		for (String s : set){
			System.out.println(s);  //aaa  bbb  ccc
		}
	}
}

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/**
 * Treeset集合来存储Integer类型
 */
public class MyTreeSet1 {
	public static void main(string[] args) {
		TreeSet<Integer> ts = new TreeSet<>();
		ts.add(5);
		ts.add(3);
		ts.add(4);
		ts.add(1);
		ts.add(2);
		System.out.println(ts);  //[1, 2, 3, 4, 5]
	}
}

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/**
 * Treeset集合来存储Student类型
*/
public class MyTreeset2 {
	public static void main(String[] args) {
		TreeSet<Student> ts = new TreeSet<>();
		Student s1 = new Student("小花"，27);
		Student s2 = new Student("小花花"，28);
		Student s3 = new Student("小小花"，28);
		ts.add(s1);
		ts.add(s2);
		ts.add(s3);
		System.out.println(ts);
		//Exception in thread "main"java.lang.ClassCastException:class com.itheima.mytreeset.Student cannot be cast to class java.lan
		//报错的原因:没有指定排序的规则,是按照身高排,还是按照年龄排...,没有制定规则
	}
}

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public class Student implements comparable<Student> { //此处的泛型要和集合里边存储的数据类型保持一致
	private String name;
	private int age;

	public student() {
	}

	public Student(String name, int age) {
		this.name = name;
		this.age = age;
	}
	
	//set/get...
	
	@Override
	public int compareTo(Student o) {
		//按照对象的年龄进行排序
		int result = this.age -o.age;
		return result;
	}
}

/**
 * Treeset集合来存储Student类型
*/
public class MyTreeset2 {
	public static void main(String[] args) {
		TreeSet<Student> ts = new TreeSet<>();
		Student s1 = new Student("小花"，28);
		Student s2 = new Student("小花花"，27);
		Student s3 = new Student("小小花"，29);
		ts.add(s1);
		ts.add(s2);
		ts.add(s3);
		//[Student{name='小花花'，age=27), Student{name='小花'，age=28}, Student{name='小小花'，age=29}]
		System.out.println(ts);
	}
}

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public class Student implements comparable<Student> { //此处的泛型要和集合里边存储的数据类型保持一致
	private String name;
	private int age;

	public student() {
	}

	public Student(String name, int age) {
		this.name = name;
		this.age = age;
	}
	
	//set/get...
	
	@Override
	public int compareTo(Student o){
		//按照对象的年龄进行排序
		int result = this.age -o.age;
		return result;
	}
}

/**
 * Treeset集合来存储Student类型
*/
public class MyTreeset2 {
	public static void main(String[] args) {
		TreeSet<Student> ts = new TreeSet<>();
		Student s1 = new Student("小花"，28);
		Student s2 = new Student("小花花"，27);
		Student s3 = new Student("小小花"，29);
		Student s4 = new Student("小黑"，28);
		ts.add(s1);
		ts.add(s2);
		ts.add(s3);
		ts.add(s4);
		//[Student{name='小花花Lage=27), Student{name='小花'，age=28}, Student{name='小小花'，age=29}]
		System.out.println(ts);
	}
}

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public class Student implements comparable<Student> { //此处的泛型要和集合里边存储的数据类型保持一致
	private String name;
	private int age;

	public student() {
	}

	public Student(String name, int age) {
		this.name = name;
		this.age = age;
	}
	
	//set/get...
	
	@Override
	public int compareTo(Student o) {
		//按照对象的年龄进行排序
		//主要判断条件
		int result = this.age -o.age;
		//次要判断条件
		result = result == 0 ? this.name.compareTo(o.getName()) : result;
		return result;
	}
}

/**
 * Treeset集合来存储Student类型
*/
public class MyTreeset2 {
	public static void main(String[] args) {
		TreeSet<Student> ts = new TreeSet<>();
		Student s1 = new Student("zhangsan"，28);
		Student s2 = new Student("lisi"，27);
		Student s3 = new Student("wangwu"，29);
		Student s4 = new Student("zhaoliu"，28);
		ts.add(s1);
		ts.add(s2);
		ts.add(s3);
		ts.add(s4);
		System.out.println(ts);
	}
}

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public static void main(String[] args) {
	String s1 = "aaa";
	String s2 = "ab";
	System.out.println(s1.compareTo(s2)); //-1
	//首先比较第一个字母，如果第一个字母是一样的，那么继续比较后面的字母
	//当不一样的时候，就拿着a对应的码表值97，减去b的码表值98
	//认为a是比b要小的
}

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public class MyTreeset4 {
	public static void main(String[] args) {

		Treeset<Teacher> ts = new Treeset<>(new Comparator<Teacher>() {  //泛型要和集合里存储的元素类型保持一致
			@Override
			public int compare(Teacher o1,Teacher o2){    //匿名内部类
				//o1表示现在要存入的那个元素
				//o2表示已经存入到集合中的元素
				//主要条件
				int result = o1.getAge() - o2.getAge();
				//次要条件
				result = result == 0 ? o1.getName().compareTo(o2.getName()) : result;
				return result;
			}
		});
	
		Teacher t1 = new Teacher("zhangsan", 23);
		Teacher t2 = new Teacher("lisi", 22);
		Teacher t3 = new Teacher("wangwu", 24);

		ts.add(t1);
		ts.add(t2);
		ts.add(t3);
	}
}

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TreeSet<String> ts = new Treeset<>(
	(String o1,string o2) -> {
		int result = o1.length() - o2.length();
		result result == 0 ? o1.compareTo(o2) : result;
		return result;
});