Cached Hadoop RDD always return rows with the same value

public final class Test {
    public static void main(String[] args) throws Exception {
        SparkConf sparkConf = new SparkConf().setAppName("Test");
        JavaSparkContext ctx = new JavaSparkContext(sparkConf);
        ... 
        JavaPairRDD<BytesWritable, BytesWritable> input = 
                ctx.hadoopRDD(jobConf, CombineHiveInputClass.class, WritableComparable.class, Writable.class);
        input = input.cache();
        input.foreach(new VoidFunction<Tuple2<BytesWritable, BytesWritable>>() {
            @Override
            public void call(Tuple2<BytesWritable, BytesWritable> row) throws Exception {
                if (row._1() != null) {
                    System.out.println("Key: " + row._1());
                }
                if (row._2() != null) {
                    System.out.println("Value: " + row._2());
                }
            }
        });
        ctx.stop();
    }
}