我用composite模式写的一个二叉树的例子 1，Component 是抽象组件 Tree 和Leaf 继承Component   private String name;         //树或叶子的名称 addChild(Component leftChild,Component rightChild);  //给一个树上加上一个左孩子，一个右孩子 getName(){return name;} getTreeInfo(){}                //得到树或叶子的详细信息 getLength();                     //得到树的高度   2，Tree  二叉树，一个左孩子，一个右孩子   3，Leaf 是叶子节点 4，Test 是测试节点   /**  Component.java    **************/ package binarytree; public abstract class   Component { private String name; public abstract Component addChild(Component leftChild,Component rightChild); public String getName(){return name;}     public void getTreeInfo(){}      public abstract int  getLength(); }   /**  Leaf.java    **************/ package binarytree; public class Leaf extends Component{  private String name;  private Component leaf=null;  public Leaf(String name) {  this.name=name;  }   public Component addChild(Component leftChild,Component rightChild){        return this;     }      public String getName(){      return name;     }       public int  getLength() {     return 1;   }  public static void main(String[] args) {  } }   /**  Tree.java    **************/ package binarytree; public class Tree extends Component {  private String name;  private Component leftChild;  private Component rightChild;  public Tree(String name,Component leftChild,Component rightChild) {  this.name=name;  this.leftChild=leftChild;  this.rightChild=rightChild;  }  public Tree(String name) {  this.name=name;  this.leftChild=null;  this.rightChild=null;  }    public Component addChild(Component leftChild,Component rightChild){    this.leftChild=leftChild;    this.rightChild=rightChild;    return this;    }    public String getName(){    return name;    }    public void getTreeInfo()         //得到树或叶子的详细信息   //先打印自己的名字，再遍例左孩子，再遍例右孩子   //如果左孩子或右孩子是树，递归调用   {    System.out.println(" this trees name is "+getName());    if(this.leftChild instanceof Leaf)    {    System.out.println(getName()+"s left child is "+this.leftChild.getName()+",it is a Leaf");    }    if(this.leftChild instanceof Tree){    System.out.println(getName()+"s left child is "+this.leftChild.getName()+",it is a Tree");    this.leftChild.getTreeInfo();    }    if(this.leftChild==null)    {    System.out.println(getName()+"s left child is a null");    }    if(this.rightChild instanceof Leaf)    {    System.out.println(getName()+"s right child is "+this.rightChild.getName()+",it is a Leaf");    }    if(this.rightChild instanceof Tree) {    System.out.println(getName()+"s right child is "+this.rightChild.getName()+",it is a Tree");    this.rightChild.getTreeInfo();    }    if(this.rightChild==null)    {    System.out.println(getName()+"s right child is a null");    }    //System.out.println(getName()+"s 高度 是 "+getLength());    }   public int  getLength() {  //比较左孩子或右孩子的高度，谁大，+1 返回  // 空孩子的处理   if(this.leftChild==null) {       if(this.rightChild==null)       return 1;       else            return this.rightChild.getLength()+1;      }   else {          if(this.rightChild==null) {           return this.leftChild.getLength()+1;                }          else {               if((this.leftChild.getLength())>=(this.rightChild.getLength()))               return this.leftChild.getLength()+1;               else               return this.rightChild.getLength()+1;               }        }   }  public static void main(String[] args) {  } }   /**  Test.java    测试类   **************/ package binarytree; public class Test {    public Test() {  }   public static void main(String[] args) {    Component tree=new Tree("luopeng");    Component leaf_child=new Leaf("luopeng1");    Component right_child=new Leaf("luopeng2");    tree=tree.addChild(leaf_child,right_child);    //tree=tree.addRightChild(right_child);    tree.getTreeInfo();    Component tree1=new Tree("luopeng2");    tree1.addChild(tree,leaf_child);    tree1.getTreeInfo();    Component tree2=new Tree("luopeng3");    tree2.addChild(tree,null);    tree2.getTreeInfo();    Component tree4=new Tree("luopeng4");    tree4.addChild(null,tree);    tree4.getTreeInfo();    System.out.println(tree4.getName()+"的高度是   "+tree4.getLength());  }