ArrayList()类中的toString()方法的重载源码

类ArrayList的toString()方法的重载

List list = new ArrayList;
System.out.println(list.toString());

 

//ArrayList类
public class ArrayList<E> extends AbstractList<E>
        implements List<E>, RandomAccess, Cloneable, java.io.Serializable

没有toString()方法，那么就找其父类

 

//AbstractList类  
public abstract class AbstractList<E> extends AbstractCollection<E> implements List<E>

没有toString()方法，那么就找其父类
 

//AbstractCollection
public abstract class AbstractCollection<E> implements Collection<E>

有了toString()方法，实际上list.toString()调用的就是下面这个方法
  
注意：这个是在抽象类中定义的非抽象方法

  public String toString() {
        Iterator<E> it = iterator();
        if (! it.hasNext())
            return "[]";

        StringBuilder sb = new StringBuilder();
        sb.append("[");
        for (;;) {
            E e = it.next();
            sb.append(e == this ? "(this Collection)" : e);
            if (! it.hasNext())
                return sb.append("]").toString();
            sb.append(",").append(" ");
        }