The Java Developers Almanac 1.4


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Home > List of Packages > java.util  [50 examples] > Collections  [7 examples]

e345. Listing the Elements of a Collection

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();
    }

 Related Examples
e342. Implementing a Queue
e343. Implementing a Stack
e344. Implementing a Least-Recently-Used (LRU) Cache
e346. Storing Primitive Types in a Collection
e347. Creating a Copy of a Collection
e348. Making a Collection Read-Only

See also: Arrays    Bits    Dates    Hash Tables    Lists    Property Files    Sets    Sorted Collections    Time    Timers   


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