我需要帮助来修复我的代码。我认为这很简单(可能是),但我无法理解。我有一个简单的加法计算器。它工作正常,但如果我将 1 或两个数字文本字段留空,程序就会崩溃。
我有我的 if 语句,但显然我并没有告诉它做正确的事情。
public class MainActivity extends Activity {
Double firstNum, secondNum, answerNum;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
final EditText first = (EditText) findViewById(R.id.txtFirst);
final EditText second = (EditText) findViewById(R.id.txtSecond);
final TextView answer = (TextView) findViewById(R.id.txtAnswer);
Button calc = (Button) findViewById(R.id.btnCalc);
calc.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
// convert pulled info to double using variable names
firstNum = Double.parseDouble(first.getText().toString());
secondNum = Double.parseDouble(second.getText().toString());
if (first == null || second == null)
{
Toast.makeText(MainActivity.this, "Please Enter value", Toast.LENGTH_SHORT).show();
}
else {
// add numbers
answerNum = (firstNum + secondNum);
//set format
DecimalFormat total = new DecimalFormat ("###,###,###.##");
answer.setText("Answer is " + total.format(answerNum));
}
}
});
}
}