Android中的空字段验证

Question

我想验证空字段然后执行简单计算。但我的代码不起作用。

我的代码：

public void onClick(View v) 
          {
            Double value = Double.parseDouble(etValue.getText().toString());
            Double answer = (double) 0;
            if(etValue.getText().toString().equals("")){
                Toast.makeText(getApplicationContext(), "Please Enter Value", Toast.LENGTH_LONG).show();
            }
            else{

                    if((spBitsBytesFrom.getSelectedItem().toString().equals("Bits")) && (spBitsBytesTo.getSelectedItem().toString().equals("Bytes")))
                    {

                        answer = value/8;
                        String stringAnswer = Double.toString(answer);
                        Answer.setText(stringAnswer);
                    }
                }
          }

Answer 1

试试这个..

if(etValue.getText().toString().trim().equals("") || etValue.getText().toString().trim().length() < 0){

       Toast.makeText(getApplicationContext(), "Please Enter Value", Toast.LENGTH_LONG).show();

}else{    

      if((spBitsBytesFrom.getSelectedItem().toString().equals("Bits")) && (spBitsBytesTo.getSelectedItem().toString().equals("Bytes"))){    
           answer = value/8;
           String stringAnswer = Double.toString(answer);
           Answer.setText(stringAnswer);
      }
}

Answer 2

试试这个...........

public void onClick(View v) 
              {
                Double value = Double.parseDouble(etValue.getText().toString());
                Double answer = (double) 0;
                String check = String.valueOf(value);
            if(check.length < 0){
                Toast.makeText(getApplicationContext(), "Please Enter Value", Toast.LENGTH_LONG).show();
            return;

            }
            else{

                    if((spBitsBytesFrom.getSelectedItem().toString().equals("Bits")) && (spBitsBytesTo.getSelectedItem().toString().equals("Bytes")))
                    {

                        answer = value/8;
                        String stringAnswer = Double.toString(answer);
                        Answer.setText(stringAnswer);
                    }
                }
          }

Answer 3

试试这段代码：

public void onClick(View v) 
{
    if(etValue.getText().toString().trim().length() == 0) {
        Toast.makeText(getApplicationContext(), "Please Enter Value", Toast.LENGTH_LONG).show();
    }
    else {
        Double value = Double.parseDouble(etValue.getText().toString());
        Double answer = (double) 0;

        if((spBitsBytesFrom.getSelectedItem().toString().equals("Bits")) && (spBitsBytesTo.getSelectedItem().toString().equals("Bytes")))
        {
            answer = value/8;
            String stringAnswer = Double.toString(answer);
            Answer.setText(stringAnswer);
        }
    }
}

Answer 4

 public void onClick(View v) 
      {
        Double value = Double.parseDouble(etValue.getText().toString());
        Double answer = (double) 0;
        String yourValue=etValue.getText().toString();
        if(yourValue.equals("")){
            Toast.makeText(getApplicationContext(), "Please Enter Value", Toast.LENGTH_LONG).show();
        }
        else{

                if((spBitsBytesFrom.getSelectedItem().toString().equals("Bits")) && (spBitsBytesTo.getSelectedItem().toString().equals("Bytes")))
                {

                    answer = value/8;
                    String stringAnswer = Double.toString(answer);
                    Answer.setText(stringAnswer);
                }
            }
      }

Answer 5

使用 TextUtil 类的android

public void onClick(View v) 
{

    if(TextUtils.isEmpty(etValue.getText().toString()))

        etValue.setError("Enter Value");
    }
    else {
        Double value = Double.parseDouble(etValue.getText().toString());
        Double answer = (double) 0;

        if((spBitsBytesFrom.getSelectedItem().toString().equals("Bits")) && (spBitsBytesTo.getSelectedItem().toString().equals("Bytes")))
        {
            answer = value/8;
            String stringAnswer = Double.toString(answer);
            Answer.setText(stringAnswer);
        }
    }
}