// 標(biāo)準(zhǔn)語法 (Java 5+)
for (ElementType element : Iterable/Array) {
    // 操作element
}

// 等效傳統(tǒng)實(shí)現(xiàn)
Iterator<ElementType> it = collection.iterator();
while (it.hasNext()) {
    ElementType element = it.next();
    // 操作element
}

List<String> list = Arrays.asList("A", "B");
for (Integer num : list) {} // 編譯錯(cuò)誤：類型不匹配

for (final String s : list) { 
    s = "new"; // 編譯錯(cuò)誤：final修飾符
}

for (Object obj : null) { ... } // 運(yùn)行時(shí)拋出NullPointerException

List<String> list = new ArrayList<>(Arrays.asList("A", "B"));
for (String s : list) {
    list.remove(s); // 拋出ConcurrentModificationException
}

List<StringBuilder> list = new ArrayList<>();
list.add(new StringBuilder("Hello"));
for (StringBuilder sb : list) {
    sb.append(" World"); // 修改對(duì)象內(nèi)部狀態(tài) ??
    sb = new StringBuilder(); // 僅改變局部引用 ??
}

int[][] matrix = {{1,2}, {3,4}};
for (int[] row : matrix) {
    for (int num : row) {
        System.out.print(num + " ");
    }
}

class MyIterable implements Iterable<String> {
    public Iterator<String> iterator() {
        return Arrays.asList("A","B").iterator();
    }
}

list.parallelStream().forEach(element -> {
    // 多線程處理（注意線程安全）
});

// 防御性復(fù)制（針對(duì)可能被修改的集合）
for (String s : new ArrayList<>(originalList)) {
    originalList.remove(s); // 安全操作
}

var entries = Map.of(1,"A",2,"B").entrySet();
for (var entry : entries) {
    System.out.println(entry.getKey() + ":" + entry.getValue());
}

record Point(int x, int y) {}
List<Point> points = List.of(new Point(1,2), new Point(3,4));
for (Point(var x, var y) : points) { // 模式匹配解構(gòu)（Java 17預(yù)覽特性）
    System.out.println(x + "," + y);
}