The error report is inexplicable, but in fact, the dependency package imported by idea has multiple options, and it is wrong.

The required dependencies are as follows:

import org.apache.flink.api.common.serialization.SimpleStringSchema;
import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;
import org.apache.flink.streaming.connectors.kafka.FlinkKafkaConsumer;

import java.util.Collections;
import java.util.List;
import java.util.Properties;