CODEWITHSUNDEEP
javaandroid
ehelmick93
ehelmick93

Reputation: 27

Java Calculator android app force closes when any operators prior to or after calculations (need exception handling help)

I am trying to figure out the best way to handle exceptions with the onClick listeners. Everything in the code works fine, EXCEPT for the fact that if I press +, -, *, /, = before entering a number or after calculating, it crashes the app. Any help would be appreciated. This code is a fragement of a multi-functional tool application that I am working on. Code below:

**edited to remove code not relevant to error and add in debugging output

public class Calculator extends Fragment {

    add.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            compute();
            ACTION = ADDITION;
            display.setText(String.valueOf(val1) + " + ");
            displayInfo.setText(null);
        }
    });

    sub.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            compute();
            ACTION = SUBTRACTION;
            display.setText(String.valueOf(val1) + " - ");
            displayInfo.setText(null);
        }
    });

    multiply.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            compute();
            ACTION = MULTIPLICATION;
            display.setText(String.valueOf(val1) + " * ");
            displayInfo.setText(null);
        }
    });

    divide.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            compute();
            ACTION = DIVISION;
            display.setText(String.valueOf(val1) + " / ");
            displayInfo.setText(null);
        }
    });

    equal.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
                compute();
                ACTION = EQUALS;
                display.setText(String.valueOf(val1));
                val1 = Double.NaN;
                val2 = Double.NaN;
                displayInfo.setText(null);
            }
        }
    });

}

@Nullable
@Override
public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
    return inflater.inflate(R.layout.calculator, container, false);
}

private void setupUIView(){

    zero = (Button)getView().findViewById(R.id.button_0);
    one = (Button)getView().findViewById(R.id.button_1);
    two = (Button)getView().findViewById(R.id.button_2);
    three = (Button)getView().findViewById(R.id.button_3);
    four = (Button)getView().findViewById(R.id.button_4);
    five = (Button)getView().findViewById(R.id.button_5);
    six = (Button)getView().findViewById(R.id.button_6);
    seven = (Button)getView().findViewById(R.id.button_7);
    eight = (Button)getView().findViewById(R.id.button_8);
    nine = (Button)getView().findViewById(R.id.button_9);
    decimal = (Button)getView().findViewById(R.id.button_dec);
    negate = (Button)getView().findViewById(R.id.button_neg);
    equal = (Button)getView().findViewById(R.id.button_eql);
    multiply = (Button)getView().findViewById(R.id.button_mult);
    add = (Button)getView().findViewById(R.id.button_add);
    sub = (Button)getView().findViewById(R.id.button_sub);
    divide = (Button)getView().findViewById(R.id.button_div);
    percent = (Button)getView().findViewById(R.id.button_prcnt);
    power = (Button)getView().findViewById(R.id.button_pwr);
    clear = (Button)getView().findViewById(R.id.button_clr);
    display = (TextView)getView().findViewById(R.id.display);
    displayInfo = (TextView)getView().findViewById(R.id.displayinfo);

}

private void compute(){
    if(!Double.isNaN(val1)){
        val2 = Double.parseDouble(displayInfo.getText().toString());

        switch (ACTION){
            case ADDITION:
                val1 = val1 + val2;
                break;
            case SUBTRACTION:
                val1 = val1 - val2;
                break;
            case MULTIPLICATION:
                val1 = val1 * val2;
                break;
            case DIVISION:
                val1 = val1 / val2;
                break;
            case EQUALS:

                break;

        }
    }

    else{
        val1 = Double.parseDouble(displayInfo.getText().toString());
    }
}

}

logcat:

    Process: myapplication, PID: 29796
    java.lang.NumberFormatException: empty String
        at sun.misc.FloatingDecimal.readJavaFormatString(FloatingDecimal.java:1842)
        at sun.misc.FloatingDecimal.parseDouble(FloatingDecimal.java:110)
        at java.lang.Double.parseDouble(Double.java:538)
        at myapplication.Calculator.compute(Calculator.java:260)
        at myapplication.Calculator.access$400(Calculator.java:19)
        at myapplication.Calculator$16.onClick(Calculator.java:187)
        at android.view.View.performClick(View.java:7870)
        at android.widget.TextView.performClick(TextView.java:14952)
        at android.view.View.performClickInternal(View.java:7839)
        at android.view.View.access$3600(View.java:886)
        at android.view.View$PerformClick.run(View.java:29315)
        at android.os.Handler.handleCallback(Handler.java:883)
        at android.os.Handler.dispatchMessage(Handler.java:100)
        at android.os.Looper.loop(Looper.java:237)
        at android.app.ActivityThread.main(ActivityThread.java:7762)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1047)

Upvotes: 1

Views: 68

Answers (1)

Marvin812
Marvin812

Reputation: 118

  val1 = Double.parseDouble(displayInfo.getText().toString());

This line should be your first problem. You are trying to set val1, but displayInfo.getText() is returning "" or NULL.

One way to fix your problem is wrapping everything inside of your onclick()-Method with an if-statement checking if the displayInfo is empty. e.g.:

        public void onClick(View v) {
        if(!(displayInfo.getText().toString().equals(""))){
            compute();
            ACTION = DIVISION;
            display.setText(String.valueOf(val1) + " / ");
            displayInfo.setText("");
        }
    }

Note that I replaced the text-reset of displayInfo with an empty String, since you are trying to concatenate null with some String, which lets your app crash after calculating once.

Upvotes: 2

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