java - 使用集合重写数组

Question

我有一个任务，我可以使用最简单的方法 - 数组来完成该任务。现在我想更进一步，使用一些更复杂的 java 功能(如集合)重做它，但我从未使用过比二维矩阵更复杂的东西。我应该看什么以及如何开始。塔应该成为一个 Collection 品吗？这是任务:

我们有两个类别 - 塔楼和街区。塔是用积木 build 的。这是用于测试的示例代码:

 Block k1=new Block("yellow",1,5,4);
 Block k2=new Block("blue",2,2,6);
 Block k3=new Block("green",3,4,2);
 Block k4=new Block("yellow",1,5,4);

 Tower tower=new Tower();
 tower.add(k1,k2,k3);

 "Added 3 blocks."

 System.out.println(tower);

 "block: green, base: 4cm x 3cm, thicknes: 2 cm
 block: blue, base: 6cm x 2cm, thicknes: 2 cm
 block: yellow, base: 5cm x 4cm, thicknes: 1 cm"

 tower.add(k2);

 "Tower already contains this block."

 tower.add(k4);

 "Added 1 block."

 System.out.println(tower);

 "block: green, base: 4cm x 3cm, thicknes: 2 cm
 block: blue, base: 6cm x 2cm, thicknes: 2 cm
 block: yellow, base: 5cm x 4cm, thicknes: 1 cm      
 block: yellow, base: 5cm x 4cm, thicknes: 1 cm"

 tower.delete(k1);

 "Deleted 1 block"

 tower.delete(k1);

 "Block not in tower"

  System.out.println(tower);

 "block: blue, base: 6cm x 2cm, thicknes: 2 cm
 block: yellow, base: 5cm x 4cm, thicknes: 1 cm      
 block: yellow, base: 5cm x 4cm, thicknes: 1 cm"

假设我将 Tower 视为 block 的集合。如何在整个集合中搜索特定 block ？或者我应该使用其他接口(interface)？

Answer 1

您可以将Set用作集合这可以防止重复元素。

如果您尝试添加已存在的元素，它将返回false。

Set<Block> set = new HashSet<Block>();

boolean added = set.add( k1 );
if( added ) {
    System.out.println("Added 1 block.");
} else {
   System.out.println("Tower already contains this block.");
}

要知道集合是否已包含元素，该类应正确实现 equals()方法。

要提供描述消息，您可以覆盖 toString()方法并迭代集合:

 for( Block b : set ) {
     System.out.println( b ); // invokes b.toString()
}