Button for editing TextView size, style

Question

I want to make buttons to adjust my text. There are buttons for making the TextView bigger, smaller, back and forth between italic and bold.

I want to edit the TextView called "text"

In the code below, when I clicked the "butBig" or "butSmall" button, both button does the same thing it makes my text size increase but not by 5, it became really big. When I clicked on either button again, the TextView disappear like it is too big for the frame.

butBig.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {
            float size = text.getTextSize();
            text.setTextSize(size + 5.0F);

        }
    });

    butSmall.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {
            float size = text.getTextSize();
            text.setTextSize(size - 5.0F);

        }
    });

For Italic and Bold, my code here does work but sometimes when I clicked either of these buttons, the app crashed for no reason..

butItalic.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {

            if (text.getTypeface().getStyle() == Typeface.BOLD) {

                text.setTypeface(null, Typeface.BOLD_ITALIC);

            } else if (text.getTypeface().getStyle() == Typeface.ITALIC) {

                text.setTypeface(null, Typeface.NORMAL);

            } else if (text.getTypeface().getStyle() == Typeface.NORMAL) {

                text.setTypeface(null, Typeface.ITALIC);

            } else if (text.getTypeface().getStyle() == Typeface.BOLD_ITALIC) {

                text.setTypeface(null, Typeface.BOLD);

            }


        }
    });


    butBold.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {

            if (text.getTypeface().getStyle() == Typeface.ITALIC) {

                text.setTypeface(null, Typeface.BOLD_ITALIC);

            } else if (text.getTypeface().getStyle() == Typeface.BOLD) {

                text.setTypeface(null, Typeface.NORMAL);

            } else if (text.getTypeface().getStyle() == Typeface.NORMAL) {

                text.setTypeface(null, Typeface.BOLD);

            } else if (text.getTypeface().getStyle() == Typeface.BOLD_ITALIC) {

                text.setTypeface(null, Typeface.ITALIC);

            }


        }
    });

Please help me with this

Thank you

Edit: Here's my logcat :)

--------- beginning of crash 11-05 05:34:17.581 2416-2416/com.example.textadjust E/AndroidRuntime: FATAL EXCEPTION: main Process: com.example.textadjust, PID: 2416 java.lang.NullPointerException: Attempt to invoke virtual method 'int android.graphics.Typeface.getStyle()' on a null object reference at com.example.textadjust.MainActivity$3.onClick(MainActivity.java:57) at android.view.View.performClick(View.java:5198) at android.view.View$PerformClick.run(View.java:21147) at android.os.Handler.handleCallback(Handler.java:739) at android.os.Handler.dispatchMessage(Handler.java:95) at android.os.Looper.loop(Looper.java:148) at android.app.ActivityThread.main(ActivityThread.java:5417) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) 11-05 05:34:19.734 2416-2416/? I/Process: Sending signal. PID: 2416 SIG: 9

Answer 1

What you should know so far is that the Size of TextSize your are doing using the method:

text.setTextSize(size + 5.0F);

The size units is Scalled Pixels and if you are wondering or want to use the size in dp here is the method to change pixels to dp :

public int getDp(int px) {
    DisplayMetrics displayMetrics = getContext().getResources().getDisplayMetrics();
    int dp = Math.round(px / (displayMetrics.xdpi / DisplayMetrics.DENSITY_DEFAULT));
    return dp;
}

Add this method in your clas for that! But alternatively ( I recommend ) you can use the method:

setTextSize(int unit, float size);

Where the parameter int unit here i can take values like as given by this stackoverflow answer :

TypedValue.COMPLEX_UNIT_PX   //Pixels

TypedValue.COMPLEX_UNIT_SP   //Scaled Pixels

TypedValue.COMPLEX_UNIT_DIP  //Device Independent Pixels

And for the other question add some logs for the crash! to figure out what might be the error and I will edit my answer to add that!!

But my suggestion so far reduce the conditions and use a switch instead of if and else s and make sure the TextView has a text before calling those methods. Add some logs to be sure whats going on!

EDIT FOR THE CRASH

As I guessed the cause for the crash is NullPointerException . Which may be caused by your variable of TextView being null . Possible causes is it is not assigned just in onCreate() or it has no text to display when assigned (I guess).

SOLUTION :

Because you are going to use the TextView in your whole class declare it as a class variable and assign it onCreate if its Activity or onCreateView if Fragment : Just inside your class before any method:

private TextView text;

Then inside onCreate assign it as:

text=(TextView)findViewById(R.id.your_text_view_id); //Replace with a real id

And set a default text or Typeface in xml or in java code. Now you can access the TextView variable everywhere in the class it will not be null .

And as a tip again for performance and readability use switch instead of if and else .