Android studio：錯(cuò)誤: 需要常量表達(dá)式

將一個(gè)項(xiàng)目作為library，通過import Moudle導(dǎo)入一個(gè)新項(xiàng)目引用時(shí)，爆出這個(gè)錯(cuò)誤：需要常量表達(dá)式，定位到switch。于是百度一下，解決方法為把switch case，改成if else，即：

  switch (v.getId()) {
            // 點(diǎn)擊了清除按鈕
            case R.id.btn_clear:
                clear();
                break;
            // 點(diǎn)擊了取消按鈕
            case R.id.btn_cancel:
                break;
            // 點(diǎn)擊了加、減、乘、除按鈕
            case R.id.btn_plus:
            case R.id.btn_minus:
            case R.id.btn_multiply:
            case R.id.btn_divide:
                operator = inputText; // 運(yùn)算符
                refreshText(showText + operator);
                break;
            // 點(diǎn)擊了等號(hào)按鈕
            case R.id.btn_equal:
                // 加減乘除四則運(yùn)算
                double calculate_result = calculateFour();
                refreshOperate(String.valueOf(calculate_result));
                refreshText(showText + "=" + result);
                break;
            // 點(diǎn)擊了開根號(hào)按鈕
            case R.id.ib_sqrt:
                double sqrt_result = Math.sqrt(Double.parseDouble(firstNum));
                refreshOperate(String.valueOf(sqrt_result));
                refreshText(showText + "√=" + result);
                break;
            // 點(diǎn)擊了求倒數(shù)按鈕
            case R.id.btn_reciprocal:
                double reciprocal_result = 1.0 / Double.parseDouble(firstNum);
                refreshOperate(String.valueOf(reciprocal_result));
                refreshText(showText + "/=" + result);
                break;
            // 點(diǎn)擊了其他按鈕，包括數(shù)字和小數(shù)點(diǎn)
            default:
                // 上次的運(yùn)算結(jié)果已經(jīng)出來了
                if (result.length() > 0 && operator.equals("")) {
                    clear();
                }

                // 無運(yùn)算符，則繼續(xù)拼接第一個(gè)操作數(shù)
                if (operator.equals("")) {
                    firstNum = firstNum + inputText;
                } else {
                    // 有運(yùn)算符，則繼續(xù)拼接第二個(gè)操作數(shù)
                    secondNum = secondNum + inputText;
                }
                // 整數(shù)不需要前面的0
                if (showText.equals("0") && !inputText.equals(".")) {
                    refreshText(inputText);
                } else {
                    refreshText(showText + inputText);
                }
                break;
        }

改為：

 @Override
    public void onClick(View v) {
        String inputText;
        if(v.getId() == R.id.btn_sqrt){
            inputText = "廠";
        } else {
            inputText = ((TextView) v).getText().toString();
        }

        if (v.getId() == R.id.btn_clear){
            clear();
        } else if (v.getId() == R.id.btn_cancel) {

        } else if (v.getId() == R.id.btn_plus || v.getId() == R.id.btn_minus || v.getId() == R.id.btn_multiply || v.getId() == R.id.btn_divide) {
            operator = inputText;
            refreshText(showText + operator);
        } else if(v.getId() == R.id.btn_equal) {
            double calculate_result = calculateFour();
            refreshOperate(String.valueOf(calculate_result));
            refreshText(showText + "=" + result);
        } else if(v.getId() == R.id.btn_sqrt) {
            double sqrt_result = Math.sqrt(Double.parseDouble(firstNum));
            refreshOperate(String.valueOf(sqrt_result));
            refreshText(showText+"廠="+result);
        } else if(v.getId() == R.id.btn_reciprocal){
            double reciprocal_result = 1.0 / Double.parseDouble(firstNum);
            refreshOperate(String.valueOf(reciprocal_result));
            refreshText(showText+"/="+result);
        } else {
            if(result.length() > 0 && operator.equals("")){
                clear();
            }
            if(operator.equals("")){
                firstNum = firstNum + inputText;
            } else {
                secondNum = secondNum + inputText;
            }
            if(showText.equals("0") && !inputText.equals(".")){
                refreshText(inputText);
            } else {
                refreshText(showText+inputText);
            }
        }
    }

具體原因：http://tools.android.com/tips/non-constant-fields.文章來源地址http://www.zghlxwxcb.cn/news/detail-834457.html

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