How can I query for the configured maximum IBM MQ queue depth in Java?

You can use MQ PCF to retrieve attribute values of a queue.

i.e.

request = new PCFMessage(CMQCFC.MQCMD_INQUIRE_Q);

/**
 * You can explicitly set a queue name like "TEST.Q1" or
 * use a wild card like "TEST.*"
 */
request.addParameter(CMQC.MQCA_Q_NAME, "*");

// Add parameter to request only local queues
request.addParameter(CMQC.MQIA_Q_TYPE, CMQC.MQQT_LOCAL);

// Add parameter to request all of the attributes of the queue
request.addParameter(CMQCFC.MQIACF_Q_ATTRS, new int [] { CMQC.MQCA_Q_NAME,
                                                         CMQC.MQIA_CURRENT_Q_DEPTH,
                                                         CMQC.MQIA_MAX_Q_DEPTH
                                                       });

responses = agent.send(request);

for (int i = 0; i < responses.length; i++)
{
   if ( ((responses[i]).getCompCode() == CMQC.MQCC_OK) &&
        ((responses[i]).getParameterValue(CMQC.MQCA_Q_NAME) != null) )
   {
      String name = responses[i].getStringParameterValue(CMQC.MQCA_Q_NAME);
      if (name != null)
         name = name.trim();

      int depth = responses[i].getIntParameterValue(CMQC.MQIA_CURRENT_Q_DEPTH);
      int maxDepth = responses[i].getIntParameterValue(CMQC.MQIA_MAX_Q_DEPTH);
   }
}

I thought I posted MQListQueueAttributes01.java to StackOverflow but I cannot find it. It is on my blog.

It is a complete and fully functioning Java/MQ/PCF program to retrieve all attributes values of a queue. If you click on "PCF" category on my blog, you will find a variety of complete sample Java/MQ/PCF programs.

One way of doing it is by using the inquire method on the MQQueue object:

import com.ibm.mq.MQException;
import com.ibm.mq.MQQueue;
import com.ibm.mq.MQQueueManager;

import static com.ibm.mq.constants.CMQC.MQIA_MAX_Q_DEPTH;
import static com.ibm.mq.constants.CMQC.MQOO_INQUIRE;

public class SampleJavaCode {
    public static void main(String[] args) throws MQException {
        MQQueueManager mqQueueManager = ...;
        MQQueue mqQueue = mqQueueManager.accessQueue("ORDER", MQOO_INQUIRE);
        int[] selectors = new int[]{MQIA_MAX_Q_DEPTH};
        int[] intAttrs = new int[1];
        byte[] charAttrs = new byte[0];
        mqQueue.inquire(selectors, intAttrs, charAttrs);
        System.out.println("Max Queue depth = " + intAttrs[0]);
    }
}