TreeSet使用示例：遍历，验证是否为空，移除treeset元素，示例treeset,下面示例演示treese

TreeSet使用示例：遍历，验证是否为空，移除treeset元素，示例treeset,下面示例演示treese

下面示例演示treeset使用，TreeSet是已排序的。

import java.util.Iterator;import java.util.TreeSet;public class TreeSetExample {   public static void main(String[] args) {    System.out.println("Tree Set Example!\n");    TreeSet<Integer> tree = new TreeSet<Integer>();    tree.add(12);    tree.add(63);    tree.add(34);    tree.add(45);    // here it test it's sorted, 63 is the last element. see output below    Iterator<Integer> iterator = tree.iterator();    System.out.print("Tree set data: ");    // Displaying the Tree set data    while (iterator.hasNext()) {        System.out.print(iterator.next() + " ");    }    System.out.println();    // Check empty or not    if (tree.isEmpty()) {        System.out.print("Tree Set is empty.");    } else {        System.out.println("Tree Set size: " + tree.size());    }    // Retrieve first data from tree set    System.out.println("First data: " + tree.first());    // Retrieve last data from tree set    System.out.println("Last data: " + tree.last());    if (tree.remove(45)) { // remove element by value        System.out.println("Data is removed from tree set");    } else {        System.out.println("Data doesn't exist!");    }    System.out.print("Now the tree set contain: ");    iterator = tree.iterator();    // Displaying the Tree set data    while (iterator.hasNext()) {        System.out.print(iterator.next() + " ");    }    System.out.println();    System.out.println("Now the size of tree set: " + tree.size());    // Remove all    tree.clear();    if (tree.isEmpty()) {        System.out.print("Tree Set is empty.");    } else {        System.out.println("Tree Set size: " + tree.size());    }   }}

输出：

Tree Set Example!Tree set data: 12 34 45 63Tree Set size: 4First data: 12Last data: 63Data is removed from tree setNow the tree set contain: 12 34 63Now the size of tree set: 3Tree Set is empty.