Iterable和Iterator结合使用的一个小例子
2019年3月11日
Iterable和Iterator结合使用的一个小例子
这篇文章主要是记录一下使用Iterable和Iterator用作迭代处理的一个例子。基于这种模式可以很方便的实现 流式处理
public class Array<T> implements Iterable<T> {
T[] values; // this contains the actual elements of the array
// Constructor that takes a "raw" array and stores it
public Array(T[] values) {
this.values = values;
}
// This is a private class that implements iteration over the elements
// of the list. It is not accessed directly by the user, but is used in
// the iterator() method of the Array class. It implements the hasNext()
// and next() methods.
class ArrayIterator implements Iterator<T> {
int current = 0; // the current element we are looking at
// return whether or not there are more elements in the array that
// have not been iterated over.
public boolean hasNext() {
if (current < Array.this.values.length) {
return true;
} else {
return false;
}
}
// return the next element of the iteration and move the current
// index to the element after that.
public T next() {
if (!hasNext()) {
throw new NoSuchElementException();
}
return values[current++];
}
}
// Return the value at a given index
public T get(int index) {
return values[index];
}
// Set the value at a given index
public void set(int index, T value) {
values[index] = value;
}
// Return the length of the array
public int length() {
return values.length;
}
// Return an iterator over the elements in the array. This is generally not
// called directly, but is called by Java when used in a "simple" for loop.
public Iterator<T> iterator() {
return new ArrayIterator();
}
// This is just a sample program that can be run to show how the Array
// class might be used.
public static void main(String[] args) {
// create an array of strings
String[] strings = new String[]{"Hello", "World"};
// create a new array to hold these strings
Array<String> array = new Array<String>(strings);
// get and print the first values (prints "Hello")
System.out.println(array.get(0));
// set the second value
array.set(1, "Javaland!");
// iterate over the array, printing "Hello\nJavaland!"
for (String s : array) {
System.out.println(s);
}
}
}
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