Android & Java Engineer
• ~1 min read • 0 comments

IllegalFormatConversionException

IllegalFormatConversionException was thrown when call TextView.setText2(R.strinig.placeholder, 2) and it works well with TextView.setText1(R.strinig.placeholder, 2). The key to resolve this error is use of spread operator.

Original Kotlin Codes

private fun TextView.setText1(@StringRes resId: Int, vararg formatArgs: Any) {
     this.context.getString(resId, *formatArgs)
}

private fun TextView.setText2(@StringRes resId: Int, vararg formatArgs: Any) {
    this.context.getString(resId, formatArgs)
}

private fun TextView.setText3(@StringRes resId: Int, count: Any) {
    this.context.getString(resId, count)
}

Decompiled java code

public final class DemoKt {
   private static final void setText1(@NotNull TextView $this$setText1, @StringRes int resId, Object... formatArgs) {
      $this$setText1.getContext().getString(resId, Arrays.copyOf(formatArgs, formatArgs.length));
   }

   private static final void setText2(@NotNull TextView $this$setText2, @StringRes int resId, Object... formatArgs) {
      $this$setText2.getContext().getString(resId, new Object[]{formatArgs});
   }

   private static final void setText3(@NotNull TextView $this$setText3, @StringRes int resId, Object count) {
      $this$setText3.getContext().getString(resId, new Object[]{count});
   }
}

References

https://stackoverflow.com/questions/40025639/android-kotlin-stringres-quantitystring https://kotlinlang.org/docs/reference/functions.html#variable-number-of-arguments-varargs