Java 提供了哪些控制流构造？

if (score >= 90) {
    grade = "A";
} else if (score >= 80) {
    grade = "B";
} else {
    grade = "F";
}

// ternary — concise if/else for a value
String status = (age >= 18) ? "adult" : "minor";

switch (day) {
    case 1: name = "Mon"; break;   // ⚠️ break needed — else it FALLS THROUGH
    case 2: name = "Tue"; break;
    default: name = "Unknown";
}

// arrow syntax: no fall-through, returns a value, more concise
String name = switch (day) {
    case 1 -> "Mon";
    case 2 -> "Tue";
    case 6, 7 -> "Weekend";   // multiple labels
    default -> "Unknown";
};

// for — known iteration count
for (int i = 0; i < 10; i++) { ... }

// enhanced for-each — iterate a collection/array
for (String item : items) { ... }

// while — condition checked BEFORE each iteration
while (condition) { ... }

// do-while — body runs at least ONCE (condition checked after)
do { ... } while (condition);

for (int i = 0; i < 10; i++) {
    if (i == 5) break;       // exit the loop entirely
    if (i % 2 == 0) continue; // skip to the next iteration
}
return result;                // exit the method

// labeled break — exit nested loops
outer:
for (...) {
    for (...) {
        if (found) break outer;   // breaks BOTH loops
    }
}