Java优学网switch语句详解：从基础语法到性能优化实战

switch(expression) {

case value1:
    // 代码块1
    break;
case value2:
    // 代码块2
    break;
default:
    // 默认代码块

}

// 良好的习惯：每个case都有明确的break switch(userType) {

case "VIP":
    discount = 0.8;
    break;
case "NEW_USER":
    discount = 0.9;
    break;
default:
    discount = 1.0;
    break;

}

// 优化前：在switch中计算 switch(calculateType(user)) {

// ... cases

}

// 优化后：预先计算 UserType type = calculateType(user); switch(type) {

case VIP: 
    processVipOrder(user);
    break;
case REGULAR:
    processRegularOrder(user); 
    break;

}