flink-learning-core/src/main/java/com/zhisheng/core/utils/StringUtils.java
/**
	 * Writes a String to the given output. The string may be null.
	 * The written string can be read with {@link #readNullableString(DataInputView)}-
	 *
	 * @param str The string to write, or null.
	 * @param out The output to write to.
	 *
	 * @throws IOException Thrown, if the writing or the serialization fails.
	 */
Writes a String to the given output. The string may be null.
The written string can be read with  #readNullableString(DataInputView)

@param str The string to write, or null.
@param out The output to write to.

@throws IOException Thrown, if the writing or the serialization fails.
Writes a String to the given output . The string may be null . The written string can be read with #readNullableString ( DataInputView ) @param str The string to write or null . @param out The output to write to . @throws IOException Thrown if the writing or the serialization fails .
public static void writeNullableString(@Nullable String str, DataOutputView out) throws IOException {
		if (str != null) {
			out.writeBoolean(true);
			writeString(str, out);
		} else {
			out.writeBoolean(false);
		}
	}
public static void writeNullableString ( @ Nullable String str , DataOutputView out ) throws IOException { if ( str != null ) { out . writeBoolean ( true ) ; writeString ( str , out ) ; } else { out . writeBoolean ( false ) ; } }
Writes a String to the given output.
Writes a String to the given output .