java - 如果任何 EditText 为空，如何禁用按钮？

Question

我试过使用 TextWatcher，但如果我创建多个 TextWatcher(每个 EditText 一个)，当我开始填写任何 EditText 时，该按钮就会启用。

例子:

public class MainActivity extends AppCompatActivity {

    EditText numberOneEditText;
    EditText numberTwoEditText;
    EditText numberThreeEditText;
    TextView sumTextView;

    public void calculate(View view) {


        String numberOneString = numberOneEditText.getText().toString();
        String numberTwoString = numberTwoEditText.getText().toString();
        String numberThreeString = numberThreeEditText.getText().toString();

        double numberOneDouble = Double.parseDouble(numberOneString);
        double numberTwoDouble = Double.parseDouble(numberTwoString);
        double numberThreeDouble = Double.parseDouble(numberThreeString);

        double sum = numberOneDouble + numberTwoDouble + numberThreeDouble;

        sumTextView.setText(sum.getText().toString())

   }



    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        numberOneEditText = findViewById(R.id.numberOneEditText);
        numberTwoEditText = findViewById(R.id.numberTwoEditText);
        numberThreeEditText = findViewById(R.id.numberThreeEditText);
        sumTextView = findViewById(R.id.sumTextView);

    }
}

Answer 1

使用TextWatcher .它将解决您的问题:

editText.addTextChangedListener(new TextWatcher() {

    @Override
    public void onTextChanged(CharSequence s, int start, int before, int count) {

       if(s.toString().trim().length()==0){
            btn.setEnabled(false);
          } else {
            btn.setEnabled(true);
          }
    }

    @Override
    public void beforeTextChanged(CharSequence s, int start, int count,
            int after) {
        // TODO Auto-generated method stub
    }

    @Override
    public void afterTextChanged(Editable s) {
        // TODO Auto-generated method stub
    }
});