65 lines
1.7 KiB
Java
65 lines
1.7 KiB
Java
// understandingcollections/AssociativeArray.java
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// (c)2016 MindView LLC: see Copyright.txt
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// We make no guarantees that this code is fit for any purpose.
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// Visit http://OnJava8.com for more book information.
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// Associates keys with values
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public class AssociativeArray<K, V> {
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private Object[][] pairs;
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private int index;
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public AssociativeArray(int length) {
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pairs = new Object[length][2];
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}
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public void put(K key, V value) {
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if(index >= pairs.length)
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throw new ArrayIndexOutOfBoundsException();
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pairs[index++] = new Object[]{ key, value };
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}
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@SuppressWarnings("unchecked")
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public V get(K key) {
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for(int i = 0; i < index; i++)
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if(key.equals(pairs[i][0]))
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return (V)pairs[i][1];
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return null; // Did not find key
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}
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@Override
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public String toString() {
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StringBuilder result = new StringBuilder();
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for(int i = 0; i < index; i++) {
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result.append(pairs[i][0].toString());
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result.append(" : ");
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result.append(pairs[i][1].toString());
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if(i < index - 1)
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result.append("\n");
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}
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return result.toString();
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}
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public static void main(String[] args) {
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AssociativeArray<String,String> map =
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new AssociativeArray<>(6);
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map.put("sky", "blue");
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map.put("grass", "green");
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map.put("ocean", "dancing");
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map.put("tree", "tall");
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map.put("earth", "brown");
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map.put("sun", "warm");
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try {
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map.put("extra", "object"); // Past the end
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} catch(ArrayIndexOutOfBoundsException e) {
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System.out.println("Too many objects!");
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}
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System.out.println(map);
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System.out.println(map.get("ocean"));
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}
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}
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/* Output:
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Too many objects!
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sky : blue
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grass : green
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ocean : dancing
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tree : tall
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earth : brown
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sun : warm
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dancing
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*/
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