package collection;

import java.util.ArrayList;
import java.util.Collection;

public class CollectionDemo1 {
  public static void main(String[] args) {
    Collection collection1 = new ArrayList(); // Collection是接口，实例化其子类
    collection1.add("红楼梦");
    collection1.add("三国演义");
    System.out.println(collection1);

    Collection collection2 = new ArrayList();
    collection2.add("西游记");
    collection2.add("水浒传");

    collection1.add(collection2);
    System.out.println(collection1);
  }
}

package collection;

import java.util.ArrayList;
import java.util.Collection;

public class CollectionDemo2 {
  public static void main(String[] args) {
    Collection collection1 = new ArrayList(); // Collection是接口，实例化其子类
    collection1.add("红楼梦");
    collection1.add("三国演义");
    collection1.add("西游记");
    collection1.add("水浒传");
    System.out.println("初始状态：" + collection1);

    boolean b1 = collection1.remove("红楼梦");
    System.out.println("是否移除了元素：" + b1);
    System.out.println("移除一个元素：" + collection1);
    System.out.println();

    Collection collection2 = new ArrayList();
    collection2.add("三国演义");
    collection2.add("西游记");
    collection2.add("平凡的世界");
    boolean b2 = collection1.removeAll(collection2); // 移除两个集合的交集，只要有一个元素被移除了，就返回true
    System.out.println("移除一个集合：" + collection1);
    System.out.println("是否移除了元素：" + b2);
    System.out.println();

    Collection collection3 = new ArrayList();
    collection3.add("平凡的世界");
    collection3.add("围城");
    boolean b3 = collection1.removeAll(collection3);// 移除两个集合的交集，只要有一个元素被移除了，就返回true
    System.out.println("移除一个集合：" + collection1);
    System.out.println("是否移除了元素：" + b3);
    System.out.println();

    collection1.clear();
    System.out.println("清除集合中的所有元素：" + collection1);
  }
}

package collection;

import java.util.ArrayList;
import java.util.Collection;

public class CollectionDemo3 {
  public static void main(String[] args) {
    Collection collection1 = new ArrayList(); // Collection是接口，实例化其子类
    collection1.add("红楼梦");
    collection1.add("三国演义");
    collection1.add("西游记");
    collection1.add("水浒传");
    System.out.println("是否包含红楼梦：" + collection1.contains("红楼梦"));

    Collection collection2 = new ArrayList();
    collection2.add("三国演义");
    collection2.add("西游记");
    collection2.add("平凡的世界");
    System.out.println("是否包含一个集合中元素：" + collection1.containsAll(collection2)); // 包含所有才包含

    System.out.println("集合是否为空：" + collection1.isEmpty());
  }
}

package collection;

import java.util.ArrayList;
import java.util.Collection;

public class CollectionDemo4 {
  public static void main(String[] args) {
    Collection collection = new ArrayList(); // Collection是接口，实例化其子类
    collection.add("红楼梦");
    collection.add("三国演义");
    collection.add("西游记");
    collection.add("水浒传");
    System.out.println("元素个数：" + collection.size());
  }
}

package collection;

import java.util.ArrayList;
import java.util.Collection;

public class CollectionDemo5 {
  public static void main(String[] args) {
    Collection collection1 = new ArrayList(); // Collection是接口，实例化其子类
    collection1.add("红楼梦");
    collection1.add("三国演义");
    collection1.add("西游记");
    collection1.add("水浒传");

    Collection collection2 = new ArrayList();
    collection2.add("西游记");
    collection2.add("水浒传");
    System.out.println(collection1.retainAll(collection2));
    System.out.println("collection1：" + collection1);
    System.out.println("collection2：" + collection2);

    Collection collection3 = new ArrayList();
    collection3.add("西游记");
    collection3.add("平凡的世界");
    System.out.println(collection1.retainAll(collection3));
    System.out.println("collection1: " + collection1);
    System.out.println("collection2: " + collection2);
  }
}

package collection;

import java.util.ArrayList;
import java.util.Collection;

public class CollectionDemo6 {
  public static void main(String[] args) {
    Collection collection = new ArrayList(); // Collection是接口，实例化其子类
    collection.add("红楼梦");
    collection.add("三国演义");
    collection.add("西游记");
    collection.add("水浒传");

    Object[] objects = collection.toArray();

    for (Object object : objects) {
      System.out.println(object);
    }
  }
}

package collection;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;

public class CollectionDemo7 {
  public static void main(String[] args) {
    Collection collection = new ArrayList(); // Collection是接口，实例化其子类
    collection.add("红楼梦");
    collection.add("三国演义");
    collection.add("西游记");
    collection.add("水浒传");

    Iterator it = collection.iterator();

    while (it.hasNext()) {
      Object object = it.next();
      System.out.println(object);
    }

    it.remove(); // 如果未调用next方法，则会抛出IllegalStateException异常
    System.out.println(collection);
  }
}