請幫助轉(zhuǎn)義 Java 中 String.split() 方法中的 NullPointExeption 錯誤。用戶輸入的字符串。它無法編譯。在變量的硬編碼的情況下，一切都很好。類計算器：public class Calculator { private String mathExpression; public void setMathExpression(String mathExpression) { this.mathExpression = mathExpression; } private String[] parts = mathExpression.split(" "); private String firstNumber1 = parts[0]; //add other elements to the array... public void calculatorRun() { //using all the variables }}類計算器測試：public class CalculatorTest { public static void main(String[] args) { Scanner scanner = new Scanner(System.in); String userAnswer = "y"; Calculator calculator = new Calculator(); while (userAnswer.equals("y")) { System.out.print("Please put the math expression: "); calculator.setMathExpression(scanner.nextLine()); calculator.calculatorRun(); } }}
2 回答
冉冉說
TA貢獻1877條經(jīng)驗 獲得超1個贊
您需要將您的split調(diào)用放入一個方法中，否則它會在您實例化Calculator. 看到這個
private String[] parts = mathExpression.split(" ");
private String firstNumber1 = parts[0];
將兩者都放入方法中 calculatorRun
瀟湘沐
TA貢獻1816條經(jīng)驗 獲得超6個贊
確保 mathExpression 不為空或為空
if(mathExpression!= null && !mathExpression.isEmpty()) {
private String[] parts = mathExpression.split(" ");
private String firstNumber1 = parts[0];
/* other code */ }
添加回答
舉報
0/150
提交
取消