为两个EditText设置TextChangedListener致应用崩溃问题求助

问题原因 #

你遇到的崩溃是因为双向文本监听触发了无限循环：

• 当monayValueEditText1输入内容时，其文本变化监听器会修改monayValueEditText2的文本
• 这又会触发monayValueEditText2的文本变化监听器，反过来修改monayValueEditText1的文本
• 如此往复，不断调用setText()，最终导致栈溢出（StackOverflowError），应用崩溃

解决方案 #

核心思路是添加一个标记位，区分文本变化是用户输入还是代码主动设置，避免触发循环逻辑。以下是修改后的代码：

private fun initListener() {
    var money = 0.0
    // 标记位：判断当前是否是代码设置文本，避免触发循环监听
    var isSettingText = false
    binding.apply {
        monayValueEditText1.addTextChangedListener(object : TextWatcher {
            override fun beforeTextChanged(s: CharSequence?, start: Int, count: Int, after: Int) {}

            override fun onTextChanged(s: CharSequence?, start: Int, before: Int, count: Int) {}

            override fun afterTextChanged(s: Editable?) {
                if (isSettingText) return // 代码设置文本时跳过监听逻辑
                val money1position = moneyValueSpinner1.selectedItemPosition
                val money2position = moneyValueSpinner2.selectedItemPosition
                
                // 安全处理空输入和非数字输入
                money = s?.toString()?.toDoubleOrNull() ?: 0.0
                // 安全处理currencyList中的空值，避免空指针
                val currency1 = currencyList.getOrNull(money1position) ?: return
                val currency2 = currencyList.getOrNull(money2position) ?: return
                val forexBuying1 = currency1.ForexBuying ?: 0.0
                val unit1 = currency1.Unit?.toDoubleOrNull() ?: 1.0
                val forexBuying2 = currency2.ForexBuying ?: 0.0
                val unit2 = currency2.Unit?.toDoubleOrNull() ?: 1.0

                val result = ((forexBuying1 / unit1) * money) / forexBuying2 / unit2
                
                // 设置标记，避免触发另一个EditText的监听
                isSettingText = true
                monayValueEditText2.setText(DecimalFormat("##.####").format(result).toString())
                isSettingText = false // 恢复标记
            }
        })

        monayValueEditText2.addTextChangedListener(object : TextWatcher {
            override fun beforeTextChanged(s: CharSequence?, start: Int, count: Int, after: Int) {}

            override fun onTextChanged(s: CharSequence?, start: Int, before: Int, count: Int) {}

            override fun afterTextChanged(s: Editable?) {
                if (isSettingText) return
                val money1position = moneyValueSpinner1.selectedItemPosition
                val money2position = moneyValueSpinner2.selectedItemPosition
                
                money = s?.toString()?.toDoubleOrNull() ?: 0.0
                val currency1 = currencyList.getOrNull(money1position) ?: return
                val currency2 = currencyList.getOrNull(money2position) ?: return
                val forexBuying1 = currency1.ForexBuying ?: 0.0
                val unit1 = currency1.Unit?.toDoubleOrNull() ?: 1.0
                val forexBuying2 = currency2.ForexBuying ?: 0.0
                val unit2 = currency2.Unit?.toDoubleOrNull() ?: 1.0

                val result = ((forexBuying2 / unit2) * money) / forexBuying1 / unit1
                
                isSettingText = true
                monayValueEditText1.setText(DecimalFormat("##.####").format(result).toString())
                isSettingText = false
            }
        })
    }
}

额外优化点 #

• 替换!!强制非空断言为安全调用?:，避免空指针异常
• 使用toDoubleOrNull()替代toDouble()，处理用户输入非数字的情况
• 用getOrNull()获取列表元素，防止索引越界

内容的提问来源于stack exchange，提问作者Ömer Seyfettin Yavuzyiğit