Example usage for java.util ArrayDeque peek

List of usage examples for java.util ArrayDeque peek

Introduction

In this page you can find the example usage for java.util ArrayDeque peek.

Prototype

public E peek() 

Source Link

Document

Retrieves, but does not remove, the head of the queue represented by this deque, or returns null if this deque is empty.

Usage

From source file:Main.java

public static void main(String[] args) {

    ArrayDeque<Integer> deque = new ArrayDeque<Integer>(8);

    deque.add(25);/*from   ww  w  .  jav  a2s .  co  m*/
    deque.add(2);
    deque.add(1);
    deque.add(18);

    // this will retrieve head of the queue
    int retval = deque.peek();
    System.out.println("Retrieved Element is " + retval);

    System.out.println(deque);
}

From source file:com.comcast.oscar.dictionary.DictionaryTLV.java

/**
 * //  w  ww  . ja v  a 2 s.com
 * @param adqsTypeHierarchyStack
        
 * @param sValue
        
 * @param joTlvDictionary JSONObject
 * @return JSONObject
 */
private static JSONObject searchAndUpdateDictionaryValue(ArrayDeque<String> adqsTypeHierarchyStack,
        JSONObject joTlvDictionary, final String sValue) {

    boolean localDebug = Boolean.FALSE;

    if (debug | localDebug)
        System.out.println("DictionaryTLV.searchAndUpdateDictionaryValue(ad,jo,s): Peek: "
                + adqsTypeHierarchyStack.peek());

    try {
        if (joTlvDictionary.getString(Dictionary.TLV_NAME).equalsIgnoreCase(adqsTypeHierarchyStack.peek())) {

            String sDataType = joTlvDictionary.getString(Dictionary.DATA_TYPE);

            //Determine Data Type and insert with correct 
            //Convert Value to Proper Data Type
            if (sDataType.equals(DataTypeDictionaryReference.DATA_TYPE_INTEGER)) {

                if (debug | localDebug)
                    System.out.println("DictionaryTLV.searchAndUpdateDictionaryValue(ad,jo,s): " + sValue);

                //Get Value
                int iValue = Integer.parseInt(sValue);

                //Insert Value into JSON Object
                joTlvDictionary.put(Dictionary.VALUE, iValue);

                if (debug | localDebug)
                    System.out.println(
                            "DictionaryTLV.searchAndUpdateDictionaryValue(ad,jo,s) -> DATA_TYPE_INTEGER: "
                                    + iValue);

            } else if (sDataType.equals(DataTypeDictionaryReference.DATA_TYPE_OID)) {
                /* DO NOTHING */
            } else if (sDataType.equals(DataTypeDictionaryReference.DATA_TYPE_BYTE_ARRAY)) {

                if (debug | localDebug)
                    System.out.println(
                            "DictionaryTLV.searchAndUpdateDictionaryValue(ad,jo,s) -> DATA_TYPE_BYTE_ARRAY: "
                                    + sValue);

                //Insert Value into JSON Object
                joTlvDictionary.put(Dictionary.VALUE, sValue);

            } else if (sDataType.equals(DataTypeDictionaryReference.DATA_TYPE_STRING_NULL_TERMINATED)) {

                if (debug | localDebug)
                    System.out.println(
                            "DictionaryTLV.searchAndUpdateDictionaryValue(ad,jo,s) -> DATA_TYPE_STRING_NULL_TERMINATED: "
                                    + sValue);

                //Insert Value into JSON Object
                joTlvDictionary.put(Dictionary.VALUE, sValue);

            } else if (sDataType.equals(DataTypeDictionaryReference.DATA_TYPE_STRING)) {

                if (debug | localDebug)
                    System.out.println(
                            "DictionaryTLV.searchAndUpdateDictionaryValue(ad,jo,s) -> DATA_TYPE_STRING: "
                                    + sValue);

                //Insert Value into JSON Object
                joTlvDictionary.put(Dictionary.VALUE, sValue);

            } else if (sDataType.equals(DataTypeDictionaryReference.DATA_TYPE_MULTI_TLV_BYTE_ARRAY)) {

                if (debug | localDebug)
                    System.out.println(
                            "DictionaryTLV.searchAndUpdateDictionaryValue(ad,jo,s) -> DATA_TYPE_MULTI_TLV_BYTE_ARRAY: "
                                    + sValue);

                //Insert Value into JSON Object
                joTlvDictionary.put(Dictionary.VALUE, sValue);

            } else if (sDataType.equals(DataTypeDictionaryReference.DATA_TYPE_TRANSPORT_ADDR_IPV4_ADDR)) {

                if (debug | localDebug)
                    System.out.println(
                            "DictionaryTLV.searchAndUpdateDictionaryValue(ad,jo,s) -> DATA_TYPE_TRANSPORT_ADDR_IPV4_ADDR: "
                                    + sValue);

                //Insert Value into JSON Object
                joTlvDictionary.put(Dictionary.VALUE, sValue);

            } else if (sDataType.equals(DataTypeDictionaryReference.DATA_TYPE_TRANSPORT_ADDR_IPV6_ADDR)) {

                if (debug | localDebug)
                    System.out.println(
                            "DictionaryTLV.searchAndUpdateDictionaryValue(ad,jo,s) -> DATA_TYPE_TRANSPORT_ADDR_IPV6_ADDR: "
                                    + sValue);

                //Insert Value into JSON Object
                joTlvDictionary.put(Dictionary.VALUE, sValue);

            } else if (sDataType.equals(DataTypeDictionaryReference.DATA_TYPE_TRANSPORT_ADDR_INET_ADDR)) {

                if (debug | localDebug)
                    System.out.println(
                            "DictionaryTLV.searchAndUpdateDictionaryValue(ad,jo,s) -> DATA_TYPE_TRANSPORT_ADDR_INET_ADDR: "
                                    + sValue);

                //Insert Value into JSON Object
                joTlvDictionary.put(Dictionary.VALUE, sValue);

            } else if (sDataType.equals(DataTypeDictionaryReference.DATA_TYPE_DOUBLE_BYTE_ARRAY)) {

                if (debug | localDebug)
                    System.out.println(
                            "DictionaryTLV.searchAndUpdateDictionaryValue(ad,jo,s) -> DATA_TYPE_DOUBLE_BYTE_ARRAY: "
                                    + sValue);

                //Insert Value into JSON Object
                joTlvDictionary.put(Dictionary.VALUE, sValue);

            } else if (sDataType.equals(DataTypeDictionaryReference.DATA_TYPE_STRING_BITS)) {

                if (debug | localDebug)
                    System.out.println(
                            "DictionaryTLV.searchAndUpdateDictionaryValue(ad,jo,s) -> DATA_TYPE_STRING_BITS: "
                                    + sValue);

                //Insert Value into JSON Object
                joTlvDictionary.put(Dictionary.VALUE, sValue);

            } else if (sDataType.equals(DataTypeDictionaryReference.DATA_TYPE_MAC_ADDRESS)) {

                if (debug | localDebug)
                    System.out.println(
                            "DictionaryTLV.searchAndUpdateDictionaryValue(ad,jo,s) -> DATA_TYPE_MAC_ADDRESS: "
                                    + sValue);

                //Insert Value into JSON Object
                joTlvDictionary.put(Dictionary.VALUE, sValue);

            } else if (sDataType.equals(DataTypeDictionaryReference.DATA_TYPE_BYTE_ARRAY_IPV4_ADDR)) {

                if (debug | localDebug)
                    System.out.println(
                            "DictionaryTLV.searchAndUpdateDictionaryValue(ad,jo,s) -> DATA_TYPE_BYTE_ARRAY_IPV4_ADDR: "
                                    + sValue);

                //Insert Value into JSON Object
                joTlvDictionary.put(Dictionary.VALUE, sValue);

            } else if (sDataType.equals(DataTypeDictionaryReference.DATA_TYPE_BYTE_ARRAY_IPV6_ADDR)) {

                if (debug | localDebug)
                    System.out.println(
                            "DictionaryTLV.searchAndUpdateDictionaryValue(ad,jo,s) -> DATA_TYPE_BYTE_ARRAY_IPV6_ADDR: "
                                    + sValue);

                //Insert Value into JSON Object
                joTlvDictionary.put(Dictionary.VALUE, sValue);

            } else if (sDataType.equals(DataTypeDictionaryReference.DATA_TYPE_BYTE)) {

                if (debug | localDebug)
                    System.out
                            .println("DictionaryTLV.searchAndUpdateDictionaryValue(ad,jo,s) -> DATA_TYPE_BYTE: "
                                    + sValue);

                //Insert Value into JSON Object
                joTlvDictionary.put(Dictionary.VALUE, sValue);

            } else if (sDataType.equals(DataTypeDictionaryReference.DATA_TYPE_OID_ASN1_OBJECT_6)) {

                if (debug | localDebug)
                    System.out
                            .println("DictionaryTLV.searchAndUpdateDictionaryValue(ad,jo,s) -> DATA_TYPE_BYTE: "
                                    + sValue);

                //Insert Value into JSON Object
                joTlvDictionary.put(Dictionary.VALUE, sValue);

            }

        }

    } catch (JSONException e) {
        e.printStackTrace();
    }

    if (debug | localDebug)
        System.out.println("DictionaryTLV.searchAndUpdateDictionaryValue(ad,jo,s): RETURN: " + joTlvDictionary);

    return joTlvDictionary;

}

From source file:com.google.gwt.emultest.java.util.ArrayDequeTest.java

public void testPeek() {
    Object o1 = new Object();
    Object o2 = new Object();
    Object o3 = new Object();

    ArrayDeque<Object> deque = new ArrayDeque<>();
    assertNull(deque.peek());

    deque.add(o1);/*from w w  w  . j  a  va 2 s .c o  m*/
    assertEquals(o1, deque.peek());
    checkDequeSizeAndContent(deque, o1);

    deque.add(o2);
    assertEquals(o1, deque.peek());
    checkDequeSizeAndContent(deque, o1, o2);

    deque.addFirst(o3);
    assertEquals(o3, deque.peek());
    checkDequeSizeAndContent(deque, o3, o1, o2);

    deque.clear();
    assertTrue(deque.isEmpty());
    assertNull(deque.peek());
}

From source file:com.google.gwt.emultest.java.util.ArrayDequeTest.java

public void testRolloverInvariants() {
    ArrayDeque<Integer> deque = new ArrayDeque<>();

    assertTrue(deque.add(1));//from  w w w.  j  a v  a 2s .  c o  m
    assertEquals(1, (int) deque.removeFirst());
    for (int i = 0; i < 100; i++) {
        assertTrue(deque.add(i));
    }
    assertNotNull(deque.peek());
    assertFalse(deque.isEmpty());

    Iterator<Integer> it = deque.iterator();
    for (int i = 0; i < 100; i++) {
        assertTrue(it.hasNext());
        assertEquals(i, (int) it.next());
        it.remove();
    }
    assertFalse(it.hasNext());
    assertNull(deque.peek());
    assertTrue(deque.isEmpty());
}