如何在变量中使用等式与if语句？推荐卡路里计算结果异常排查

打印recommendedCalories变量时，传入默认值0会输出0，但使用前一页面传递的变量值时，本该得到不同结果却没达到预期，等式计算为何没得到想要的结果？

原代码 #

package com.example.optilife

import...

class WelcomeActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_welcome)

        val userAge = intent.getIntExtra("EXTRA_AGE", 0)
        val userHeight = intent.getIntExtra("EXTRA_HEIGHT", 0)
        val userWeight = intent.getIntExtra("EXTRA_WEIGHT", 0)
        val userGender = intent.getStringExtra("EXTRA_GENDER")
        val userActivityLevel = intent.getStringExtra("EXTRA_ACTIVITYLEVEL")
        var userWeightGoal = intent.getStringExtra("EXTRA_WEIGHTGOAL")
        var userWeightGoalCalories = {
            userWeightGoal = if (userWeightGoal == "Weight loss") {
                "300"
            } else if (userWeightGoal == "Maintain weight") {
                "0"
            } else {
                "-300"
            }
        }

        var recommendedCalories = 0
        var recommendedCaloriesCalculator = {
            recommendedCalories = if (userGender == "Male") {
                (66 + 13.7userWeight + 5userHeight - 6.8userAge -                     
userWeightGoal.toString().toInt()).toString().toInt()
            } else {
                (655 + 9.6userWeight + 1.8userHeight - 4.7userAge -    
userWeightGoal.toString().toInt()).toString().toInt()
            }
    }

        findViewById<TextView>(R.id.tv_Test).apply {
            text = recommendedCalories.toString()
        }
    }
}

问题原因 #

• 你定义了userWeightGoalCalories和recommendedCaloriesCalculator两个lambda表达式，但完全没调用它们，里面的转换和计算逻辑根本没执行，recommendedCalories一直是初始值0。
• 代码存在语法错误：Kotlin中乘法必须写*运算符，13.7userWeight、5userHeight这种写法会直接编译失败，根本跑不到计算步骤。
• userWeightGoal本身就是字符串类型，不需要额外调用toString()，冗余操作无意义。

修正后的代码 #

package com.example.optilife

import...

class WelcomeActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_welcome)

        val userAge = intent.getIntExtra("EXTRA_AGE", 0)
        val userHeight = intent.getIntExtra("EXTRA_HEIGHT", 0)
        val userWeight = intent.getIntExtra("EXTRA_WEIGHT", 0)
        val userGender = intent.getStringExtra("EXTRA_GENDER")
        val userActivityLevel = intent.getStringExtra("EXTRA_ACTIVITYLEVEL")
        var userWeightGoal = intent.getStringExtra("EXTRA_WEIGHTGOAL")

        // 直接执行体重目标转换逻辑，无需用lambda包裹
        userWeightGoal = when(userWeightGoal) {
            "Weight loss" -> "300"
            "Maintain weight" -> "0"
            else -> "-300"
        }

        // 直接计算推荐热量，避免冗余的变量赋值
        val recommendedCalories = if (userGender == "Male") {
            (66 + 13.7 * userWeight + 5 * userHeight - 6.8 * userAge - userWeightGoal.toInt()).toInt()
        } else {
            (655 + 9.6 * userWeight + 1.8 * userHeight - 4.7 * userAge - userWeightGoal.toInt()).toInt()
        }

        findViewById<TextView>(R.id.tv_Test).apply {
            text = recommendedCalories.toString()
        }
    }
}

修正说明 #

1. 移除了未调用的lambda表达式，直接执行转换和计算逻辑，确保代码能运行到关键计算步骤。
2. 补充了缺失的乘法运算符*，修复编译错误。
3. 用when语句替代嵌套if-else，代码更简洁易读。
4. 删除了冗余的toString()调用，优化代码逻辑。

内容的提问来源于stack exchange，提问作者JenairoB