如何在edittext中输入正好4个数字/字母时运行代码

Question

如果在edittext中输入了4个数字/字母,我该如何运行一些代码？

Answer 1

您需要做的就是在您的edittext中添加TextWatcher.

myEditText.addTextChangedListener(new TextWatcher() {
@Override
public void onTextChanged(CharSequence s, int start, int before, int count) {
  if(messageText.getText().length() == 4){
    //call a function here
  }
}
@Override
public void afterTextChanged(Editable s) {}
@Override
public void beforeTextChanged(CharSequence s, int start, int count, int after) {}
});