当editText字段为空时活动崩溃

Question

我已经看到了一些与我的类似的其他标题，但我的不同之处在于输入的字符串被解析为双精度，只要填充了所有 editText 字段，它就可以正常工作，但如果一个字段是留空它会回到最后一个活动！老实说，logcat 中的错误是模糊的，我认为它在谈论这样一个事实，即我已经实现的下一个活动的按钮没有意图，但它仍然崩溃，所以我不确定在哪里我错了。任何建议将不胜感激，这是我的代码和 logcat 错误：

package com.example.siuni.mymedicare;

import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

public class weighinscreen extends ActionBarActivity {

    private Button result;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.weighinscreen);

        result = (Button) findViewById(R.id.button1);

        Button btn = (Button) findViewById(R.id.button1);
        btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {


                EditText txtTempC = (EditText) findViewById(R.id.editText1);
                String strC = txtTempC.getText().toString();
                double TempC = Double.parseDouble(strC);//Parses the string as double

                EditText txtTempF = (EditText) findViewById(R.id.editText2);
                String strF = txtTempF.getText().toString();
                double TempF = Double.parseDouble(strF););//Parses the string as double


                EditText txtBPS = (EditText) findViewById(R.id.editText3);
                String strBPS = txtBPS.getText().toString();
                double BPS = Double.parseDouble(strBPS););//Parses the string as double


                EditText txtBPD = (EditText) findViewById(R.id.editText4);
                String strBPD = txtBPD.getText().toString();
                double BPD = Double.parseDouble(strBPD););//Parses the string as double


                EditText txtHeartR = (EditText) findViewById(R.id.editText5);
                String strH = txtHeartR.getText().toString();
                double HeartR = Double.parseDouble(strH););//Parses the string as double


                if (Double.compare(TempC, Double.NaN) == 0) {//Should check the double to see if it null and produce 

                    Toast.makeText(getApplicationContext(), "Please enter your temperature",
                            Toast.LENGTH_SHORT).show();
                    result.setEnabled(true);

                } else if (Double.compare(TempF, Double.NaN) == 0){//Should check the double to see if it null and produce the toast


                    Toast.makeText(getApplicationContext(), "Please enter your temperature",
                            Toast.LENGTH_SHORT).show();
                    result.setEnabled(true);
                } else if (Double.compare(BPS, Double.NaN) == 0) {//Should check the double to see if it null and produce the toast


                    Toast.makeText(getApplicationContext(), "Please enter your blood pressure",
                            Toast.LENGTH_LONG).show();
                    result.setEnabled(true);

                } else if (Double.compare(BPD, Double.NaN) == 0) {//Should check the double to see if it null and produce the toast


                    Toast.makeText(getApplicationContext(), "Please enter your blood pressure",
                            Toast.LENGTH_LONG).show();
                    result.setEnabled(true);

                } else if (Double.compare(HeartR, Double.NaN) == 0{//Should check the double to see if it null and produce the toast


                    Toast.makeText(getApplicationContext(), "Please enter your heart rate",
                            Toast.LENGTH_LONG).show();
                    result.setEnabled(true);

                } else if (TempC <=36 && TempF <= 99 && BPS <= 100 && BPD <= 40 && HeartR <= 60) {//If the doubles are equal to the figures produces the toast

                    Toast.makeText(getApplicationContext(), "Please enter contact your GP",
                            Toast.LENGTH_LONG).show();
                     startActivity(new Intent(weighinclass.this, register.class));//moves on the next actvity
                    result.setEnabled(false);

                }
            }
        });
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.menu_main_activity2, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {

        int id = item.getItemId();

        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }
}

还有错误：

05-14 08:57:56.944    2392-2407/com.example.siuni.mymedicare W/EGL_emulation﹕ eglSurfaceAttrib not implemented
05-14 08:57:56.944    2392-2407/com.example.siuni.mymedicare W/OpenGLRenderer﹕ Failed to set EGL_SWAP_BEHAVIOR on surface 0xa6cc21c0, error=EGL_SUCCESS

Answer 1

如果您在 EditText 中提供空值，应用程序将崩溃。

您在 onClick 中获得 EditText 中的字符串（有时为空）并 试图解析它。

它将在您的代码中 throw a NumberFormatException 并且您是 not using any Exception handling mechanism 。所以很明显你的应用程序会崩溃。

提供一些检查，例如

if(!strH.equals("")){    
double HeartR = Double.parseDouble(strH););
}
else{
Toast.makeText(getApplicationContext(), "Please enter your Heart Rate",Toast.LENGTH_LONG).show();
}

注意：提供的日志与您的问题无关。正确的日志会是这样的

java.lang.NumberFormatException: Invalid double: ""