Java如何遍歷列印集合？

在Java程式設計中，如何遍歷列印集合？

以下範例如何使用Util類的tMap.keySet()，tMap.values()和tMap.firstKey()方法列印集合。

package com.yiibai;

import java.util.*;

public class PrintCollection {
    public static void main(String[] args) {
        System.out.println("Tree Map Example!\n");
        TreeMap<Integer, String> tMap = new TreeMap<Integer, String>();
        tMap.put(1, "Sunday");
        tMap.put(2, "Monday");
        tMap.put(3, "Tuesday");
        tMap.put(4, "Wednesday");
        tMap.put(5, "Thursday");
        tMap.put(6, "Friday");
        tMap.put(7, "Saturday");
        System.out.println("Keys of tree map: " + tMap.keySet());
        System.out.println("Values of tree map: " + tMap.values());
        System.out.println("Key: 5 value: " + tMap.get(5) + "\n");
        System.out.println("First key: " + tMap.firstKey() + " Value: " + tMap.get(tMap.firstKey()) + "\n");
        System.out.println("Last key: " + tMap.lastKey() + " Value: " + tMap.get(tMap.lastKey()) + "\n");
        System.out.println("Removing first data: " + tMap.remove(tMap.firstKey()));
        System.out.println("Now the tree map Keys: " + tMap.keySet());
        System.out.println("Now the tree map contain: " + tMap.values() + "\n");
        System.out.println("Removing last data: " + tMap.remove(tMap.lastKey()));
        System.out.println("Now the tree map Keys: " + tMap.keySet());
        System.out.println("Now the tree map contain: " + tMap.values());
    }
}

上述程式碼範例將產生以下結果。

Tree Map Example!

Keys of tree map: [1, 2, 3, 4, 5, 6, 7]
Values of tree map: [Sunday, Monday, Tuesday, Wednesday, Thursday, Friday, Saturday]
Key: 5 value: Thursday

First key: 1 Value: Sunday

Last key: 7 Value: Saturday

Removing first data: Sunday
Now the tree map Keys: [2, 3, 4, 5, 6, 7]
Now the tree map contain: [Monday, Tuesday, Wednesday, Thursday, Friday, Saturday]

Removing last data: Saturday
Now the tree map Keys: [2, 3, 4, 5, 6]
Now the tree map contain: [Monday, Tuesday, Wednesday, Thursday, Friday]