空时 EditText 崩溃

Question

so I have an EditText field,and when the user tap a number,its start counting down. The problem starts when the are not entering a number the app crash.

this is what I tried to do:

Thanks for the help.

---

public class MainActivity extends AppCompatActivity {

    EditText mEnterNumber;
    TextView mTest;
    int timerIsRunning = 0;

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

    public void StartRemainder(View view){
    
        mTest = findViewById(R.id.mTest);
        mEnterNumber = findViewById(R.id.mEnterNumber);
    
        int userNumb = Integer.parseInt(mEnterNumber.getText().toString()) * 60000;
    
    
        if(userNumb < 0 || mEnterNumber.toString().isEmpty()){
            Toast.makeText(MainActivity.this, "Please enter correct number", Toast.LENGTH_SHORT).show();
        }
        else{
    
        CountDownTimer userTimer = new CountDownTimer(userNumb,1000) {
    
            @Override
            public void onTick(long millisUntilFinished) {
    
                long millis = millisUntilFinished;
    
                //Convert milliseconds into hour,minute and seconds
                String hms = String.format("%02d:%02d:%02d",
                        TimeUnit.MILLISECONDS.toHours(millis),
                        TimeUnit.MILLISECONDS.toMinutes(millis) - TimeUnit.HOURS.toMinutes(TimeUnit.MILLISECONDS.toHours(millis)), TimeUnit.MILLISECONDS.toSeconds(millis) - TimeUnit.MINUTES.toSeconds(TimeUnit.MILLISECONDS.toMinutes(millis)));
                mTest.setVisibility(View.VISIBLE);
                mTest.setText(hms);
                timerIsRunning = 1;
    
            }
    
    
    
            @Override
            public void onFinish() {
    
    
            }
        }.start();
        }
    
    }

----------------------This is the error I get when the app crash:--------------------------------

2020-09-04 04:09:15.024 27096-27096/com.example.drinkme E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.drinkme, PID: 27096
java.lang.IllegalStateException: Could not execute method for android:onClick
    at androidx.appcompat.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:414)
    at android.view.View.performClick(View.java:6256)
    at android.view.View$PerformClick.run(View.java:24701)
    at android.os.Handler.handleCallback(Handler.java:789)
    at android.os.Handler.dispatchMessage(Handler.java:98)
    at android.os.Looper.loop(Looper.java:164)
    at android.app.ActivityThread.main(ActivityThread.java:6541)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767)
 Caused by: java.lang.reflect.InvocationTargetException
    at java.lang.reflect.Method.invoke(Native Method)
    at androidx.appcompat.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:409)
    at android.view.View.performClick(View.java:6256) 
    at android.view.View$PerformClick.run(View.java:24701) 
    at android.os.Handler.handleCallback(Handler.java:789) 
    at android.os.Handler.dispatchMessage(Handler.java:98) 
    at android.os.Looper.loop(Looper.java:164) 
    at android.app.ActivityThread.main(ActivityThread.java:6541) 
    at java.lang.reflect.Method.invoke(Native Method) 
    at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240) 
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767) 
 Caused by: java.lang.NumberFormatException: For input string: ""
    at java.lang.Integer.parseInt(Integer.java:620)
    at java.lang.Integer.parseInt(Integer.java:643)
    at com.example.drinkme.MainActivity.StartRemainder(MainActivity.java:40)
    at java.lang.reflect.Method.invoke(Native Method) 
    at androidx.appcompat.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:409) 
    at android.view.View.performClick(View.java:6256) 
    at android.view.View$PerformClick.run(View.java:24701) 
    at android.os.Handler.handleCallback(Handler.java:789) 
    at android.os.Handler.dispatchMessage(Handler.java:98) 
    at android.os.Looper.loop(Looper.java:164) 
    at android.app.ActivityThread.main(ActivityThread.java:6541) 
    at java.lang.reflect.Method.invoke(Native Method) 
    at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240) 
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767)

line of error:

int userNumb = Integer.parseInt(mEnterNumber.getText().toString()) * 60000;

Answer 1

I'm guessing the issue is with this line:

int userNumb = Integer.parseInt(mEnterNumber.getText().toString()) * 60000;

And it is because, an empty string( "" ) cannot be converted to a number unlike strings like "1" or "2"

To fix this: We Provide a try-catch block for the NumberFormatException

int userNumb = 0;
try {
    if (mEnterNumber != null && !TextUtils.isEmpty(mEnterNumber.getText().toString())) {
        userNumb = Integer.parseInt(mEnterNumber.getText().toString()) * 60000; 
    }
} 
catch (NumberFormatException ex) {}

Answer 2

You're not getting the text from the edittext before checking weather it's empty or not. Try this :

if(userNumb < 0 && mEnterNumber.`getText()`.toString().isEmpty()){
    Toast.makeText(MainActivity.this, "Please enter correct number", 
    Toast.LENGTH_SHORT).show();
    int userNumb = Integer.parseInt(mEnterNumber.getText().toString()) * 60000;
}

As you can see I've put the integer conversion in the if block as it might also be the reason for it.

Answer 3

Like Felix Favour said it's because you're trying to parse a non-numeric item into a string. This line:

mEnterNumber = findViewById(R.id.mEnterNumber);

Will most likely resolve to Null if nothing is entered. You can try setting it to a numeric value:

    mEnterNumber = findViewById(R.id.mEnterNumber);
    if mEnterNumber.getText().toString().equals("")
    {
        int userNumb = 0;  // or whatever value you want to set as a starting default
    }
    else
    {
        int userNumb = Integer.parseInt(mEnterNumber.getText().toString()) * 60000;
    }

This invariably could need more improvement for checking or preventing other non-numeric entries ofcourse.

Alternatively, you can also set it in the XML like this:

    <EditText
    android:id="@+id/mEnterNumber"
    ...
    android:text="0" />

Answer 4

I use something like this -

if (mEnterNumber.getText().toString().matches("")){
            Toast.makeText(this, "Please Enter any number", Toast.LENGTH_SHORT).show();
            return;
        }

I hope this will prevent the crash.