public final int getTargetByte(int baseAddress) {
    int relativeTarget = getTarget(baseAddress);

    if (relativeTarget != (byte) relativeTarget) {
      throw new DexException("Target out of range: " + Hex.s4(relativeTarget));
    }

    return relativeTarget & 0xff;
  }
Gets the target as a relative offset from the given base address, masked to be a byte in size.
This will throw if the value is out of the range of a signed byte.
android/android_framework/dex-maker/src/main/java/com/android/dx/io/instructions/DecodedInstruction.java