Android中的TextView.setText

Question

I'm new to Android development and I want to understand how TextView.setText method works. In this example,

private TrueFalse[] mQuestionBank = new TrueFalse[]
        {
                new TrueFalse(R.string.question_oceans, true),
                new TrueFalse(R.string.question_mideast, false),
                new TrueFalse(R.string.question_africa, false),
        };

private  int mCurrentIndex = 0;
mQuestionTextView = (TextView) findViewById(R.id.question_text_view);
int question = mQuestionBank[mCurrentIndex].getQuestion();
mQuestionTextView.setText(question);

The point I can't understand is how can setText return question text by only getting an int? How can an int be sufficient? Could you explain that to me? Thanks.

Answer 1

When you add a String to the String files it generate a reference in the R file and this reference is a int and it can be used on the code and in the xml file like:

<TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/question_oceans" />

The reference of the String "R.string.question_oceans" in the R file is an int, so SetText can accept int (from the reference) and can accept a real Strings like "my string".

Answer 2

int here, is the id of String value which defined in the string.xml. So textView.setText(int resid) get value as string then set internally.

Here's the source code of TextView.

public final void setText(CharSequence text) {
        setText(text, mBufferType);
}

// So this get string value from resources and use the above setText().
public final void setText(int resid) {
    setText(getContext().getResources().getText(resid));
}

You can avoid getting string value from resources and make your code simpler.