我希望应用程序在用户将请求的两个值输入到 edittext 时自动计算,而不需要按钮。
有没有办法在不使用 TextWatcher 的情况下做到这一点?
这是我的尝试。为什么不起作用?当在 edittext 中输入数字时,应用程序会强制关闭。
'
public class BodyMassIndex extends Activity
{
double result;
EditText age, height, weight;
TextView tvResult;
int ageInt;
@Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.bmi);
initialize();
TextWatcher textWatcher = new TextWatcher() {
@Override
public void afterTextChanged(Editable s) {
// TODO Auto-generated method stub
calculate();
}
@Override
public void beforeTextChanged(CharSequence s, int start, int count,
int after) {
// TODO Auto-generated method stub
}
@Override
public void onTextChanged(CharSequence s, int start, int before,
int count) {
// TODO Auto-generated method stub
}
};
height.addTextChangedListener(textWatcher);
weight.addTextChangedListener(textWatcher);
}
private void initialize() {
// TODO Auto-generated method stub
age = (EditText) findViewById(R.id.etAge);
height = (EditText) findViewById(R.id.etHeight);
weight = (EditText) findViewById(R.id.etWeight);
tvResult = (TextView) findViewById(R.id.tvResult);
}
private void calculate() {
// TODO Auto-generated method stub
double heightInt = 1;
double weightInt = 0;
if (height != null)
heightInt = Double.parseDouble(height.getText().toString());
if (weight != null)
weightInt = Double.parseDouble(weight.getText().toString());
result = weightInt / (heightInt * heightInt);
String textResult = "Your BMI is " + result;
tvResult.setText(textResult);
}}
'
最佳答案
您应该将 edittext 的默认值设置为 0。它可能会强制关闭,因为您正在尝试从其中没有任何内容的 edittext 中解析空字符串;
编辑:试试这个
if (height != null)
heightInt = Double.parseDouble(!height.getText().toString().equals("")?
height.getText().toString() : "0");
if (weight != null)
weightInt = Double.parseDouble(!weight.getText().toString().equals("")?
weight.getText().toString() : "0");
这样你就可以使用一个条件,无论什么情况你都会解析一个不会抛出异常的值
关于java - 使用 TextWatcher 获取输入到两个编辑文本中的值,并在没有按钮的情况下将这些值相乘。自动计算。,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/18091425/