e345. listing the elements of a collection.txt

这里面包含了一百多个JAVA源文件

This example demonstrates how to iterate over the elements of various types of collections. 
    // For a set or list
    for (Iterator it=collection.iterator(); it.hasNext(); ) {
        Object element = it.next();
    }
    
    // For keys of a map
    for (Iterator it=map.keySet().iterator(); it.hasNext(); ) {
        Object key = it.next();
    }
    
    // For values of a map
    for (Iterator it=map.values().iterator(); it.hasNext(); ) {
        Object value = it.next();
    }
    
    // For both the keys and values of a map
    for (Iterator it=map.entrySet().iterator(); it.hasNext(); ) {
        Map.Entry entry = (Map.Entry)it.next();
        Object key = entry.getKey();
        Object value = entry.getValue();
    }