如果edittext为空，如何读取

Question

I have an edittext . If the edit text is not empty, as shown in the code, everything works fine. However, if the edittext is empty, the app crashes when the button is pressed. It seems as if the else{} block doesn't work as intended. i have tried many different other ways to see if edittext is empty or not, such as contains() , length()>0, etc..

b.setOnClickListener(new OnClickListener(){
        public void onClick(View v){

//////////////////////////////////// Row 1 Start /////////////////////////////
        String credit1s = credit1.getText().toString();

        if (!TextUtils.isEmpty(credit1s)) {
        // call parseDouble in here
        double credit_1 = Double.parseDouble(credit1s);
        double CE1 = 0;
            if(grade1.getText().toString().toUpperCase().equals("A")) 
                CE1 = 4.0*credit_1;
            else if(grade1.getText().toString().toUpperCase().equals("B+")) 
                CE1 = 3.5*credit_1;
            else if(grade1.getText().toString().toUpperCase().equals("B")) 
                CE1 = 3.0*credit_1;
            else if(grade1.getText().toString().toUpperCase().equals("C+")) 
                CE1 = 2.5*credit_1;
            else if(grade1.getText().toString().toUpperCase().equals("C")) 
                CE1 = 2.0*credit_1;
            else if(grade1.getText().toString().toUpperCase().equals("D")) 
                CE1 = 1.0*credit_1;
            else if(grade1.getText().toString().toUpperCase().equals("F")) 
                CE1 = 0.0*credit_1;
            else if(grade1.getText().toString().toUpperCase().equals(""))
                CE1 = 0;
            ce.setText(Double.toString(CE1));
        }


 else{
            double CE1;
            CE1=0;
                    ce.setText(Double.toString(CE1));
        }

LogCat:

07-26 19:21:18.640: W/asset(11731): Copying FileAsset 0x779b8390 (zip:/data/app/com.example.rutgersgpacalculator-2.apk:/resources.arsc) to buffer size 108076 to make it aligned.
07-26 19:21:18.950: I/Adreno-EGL(11731): <qeglDrvAPI_eglInitialize:385>: EGL 1.4 QUALCOMM build: AU_LINUX_ANDROID_KK_3.5_RB1.04.04.02.006.066_msm8974_refs/tags/AU_LINUX_ANDROID_KK_3.5_RB1.04.04.02.006.066__release_AU ()
07-26 19:21:18.950: I/Adreno-EGL(11731): OpenGL ES Shader Compiler Version: E031.24.00.06
07-26 19:21:18.950: I/Adreno-EGL(11731): Build Date: 02/06/14 Thu
07-26 19:21:18.950: I/Adreno-EGL(11731): Local Branch: 
07-26 19:21:18.950: I/Adreno-EGL(11731): Remote Branch: refs/tags/AU_LINUX_ANDROID_KK_3.5_RB1.04.04.02.006.066
07-26 19:21:18.950: I/Adreno-EGL(11731): Local Patches: NONE
07-26 19:21:18.950: I/Adreno-EGL(11731): Reconstruct Branch: NOTHING
07-26 19:21:19.030: I/InputMethodManager(11731): [startInputInner] EditorInfo { packageName=com.example.rutgersgpacalculator, inputType=0x20001, imeOptions=0x48000005, privateImeOptions=null }, windowGainingFocus=android.view.ViewRootImpl$W@41ae1e58, mServedView=android.widget.EditText{41a8e9b8 VFED..CL .F....ID 0,193-270,311 #7f05003f app:id/Course1}
07-26 19:21:23.740: I/InputMethodManager(11731): [startInputInner] EditorInfo { packageName=com.example.rutgersgpacalculator, inputType=0x2002, imeOptions=0x8004005, privateImeOptions=null }, windowGainingFocus=null, mServedView=android.widget.EditText{41aa6d78 VFED..CL .F.P..ID 270,193-420,311 #7f050046 app:id/editText7}
07-26 19:21:26.580: I/InputMethodManager(11731): [startInputInner] EditorInfo { packageName=com.example.rutgersgpacalculator, inputType=0x20001, imeOptions=0x48000005, privateImeOptions=null }, windowGainingFocus=null, mServedView=android.widget.EditText{41a9e298 VFED..CL .F.P..ID 451,193-594,311 #7f05004b app:id/editText13}
07-26 19:21:28.600: W/dalvikvm(11731): threadid=1: thread exiting with uncaught exception (group=0x41624e18)
07-26 19:21:28.610: E/AndroidRuntime(11731): FATAL EXCEPTION: main
07-26 19:21:28.610: E/AndroidRuntime(11731): Process: com.example.rutgersgpacalculator, PID: 11731
07-26 19:21:28.610: E/AndroidRuntime(11731): java.lang.NumberFormatException: Invalid double: ""
07-26 19:21:28.610: E/AndroidRuntime(11731):    at java.lang.StringToReal.invalidReal(StringToReal.java:63)
07-26 19:21:28.610: E/AndroidRuntime(11731):    at java.lang.StringToReal.parseDouble(StringToReal.java:248)
07-26 19:21:28.610: E/AndroidRuntime(11731):    at java.lang.Double.parseDouble(Double.java:295)
07-26 19:21:28.610: E/AndroidRuntime(11731):    at com.example.rutgersgpacalculator.MainActivity$1.onClick(MainActivity.java:423)
07-26 19:21:28.610: E/AndroidRuntime(11731):    at android.view.View.performClick(View.java:4480)
07-26 19:21:28.610: E/AndroidRuntime(11731):    at android.view.View$PerformClick.run(View.java:18686)
07-26 19:21:28.610: E/AndroidRuntime(11731):    at android.os.Handler.handleCallback(Handler.java:733)
07-26 19:21:28.610: E/AndroidRuntime(11731):    at android.os.Handler.dispatchMessage(Handler.java:95)
07-26 19:21:28.610: E/AndroidRuntime(11731):    at android.os.Looper.loop(Looper.java:157)
07-26 19:21:28.610: E/AndroidRuntime(11731):    at android.app.ActivityThread.main(ActivityThread.java:5872)
07-26 19:21:28.610: E/AndroidRuntime(11731):    at java.lang.reflect.Method.invokeNative(Native Method)
07-26 19:21:28.610: E/AndroidRuntime(11731):    at java.lang.reflect.Method.invoke(Method.java:515)
07-26 19:21:28.610: E/AndroidRuntime(11731):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:852)
07-26 19:21:28.610: E/AndroidRuntime(11731):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:668)
07-26 19:21:28.610: E/AndroidRuntime(11731):    at dalvik.system.NativeStart.main(Native Method)

Answer 1

It sounds like either credit1 , the EditText object or the CharSequence returned by getText() is null. Without a Logcat posting, I can't be sure which.

You should first make sure credit1s is not null and neither is credit1s.getText():

String credit1s = "";

if (credit1 != null && credit1.getText() != null) {
    credit1s = credit1.getText().toString();
}

if (!TextUtils.isEmpty(credit1s)) {

....

Answer 2

YOu can simply check the length of edittext by this code

 EditText ed = (EditText) findViewById(R.id.age);

String ed_text = ed.getText().toString().trim();

if(ed_text.isEmpty() || ed_text.length() == 0 || ed_text.equals("") || ed_text == null)
{
    //EditText is empty
}
else
{
    //EditText is not empty
}

or simply by

if(ed_text.length()>0){
// EMPTY
}else{
//NOT EMPTY
}