Ich habe eine Klasse „Person“ in JavaScript und Java geschrieben, um zu zeigen, wie Namensräume (engl. namespaces) und Objektorientierung in beiden Programmiersprachen aussehen.
Objektorientierung in JavaScript und Java weiterlesen
Schlagwort: class
Converting Java Collections, Array of Wrapper Types and Array of Primitives
With this post I just want to show how to convert a Java collection into an array and how to convert a wrapper class array into an array of the corresponding primitive data type. As a bonus I will show how to iterate over an ArrayList.
Code
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 | public static void main(String[] args) { // Java collection (ArrayList) with Floats ArrayList<Float> someFloats = new ArrayList<Float>(); someFloats.add(3.72f); someFloats.add(28.07f); someFloats.add(2011f); // Convert ArrayList into an array Float[] floatWrapperArray = someFloats.toArray(new Float[someFloats.size()]); float[] floatArray = new float[floatWrapperArray.length]; // Transfer array of Wrapper type (Float) into array of primitive data type (float) for (int i = 0; i < floatArray.length; i++) { floatArray[i] = floatWrapperArray[i].floatValue(); } // 1. Float ArrayList System.out.println("1. Float ArrayList"); for (Iterator iterator = someFloats.iterator(); iterator.hasNext();) { Float currentFloat = (Float) iterator.next(); System.out.println(currentFloat); } // 2. Float array System.out.println("2. Float array"); for (int i = 0; i < floatWrapperArray.length; i++) { System.out.println(floatWrapperArray[i]); } // 3. float array System.out.println("3. float array"); for (int i = 0; i < floatArray.length; i++) { System.out.println(floatArray[i]); } } |
Output
1 2 3 4 5 6 7 8 9 10 11 12 | 1. Float ArrayList 3.72 28.07 2011.0 2. Float array 3.72 28.07 2011.0 3. float array 3.72 28.07 2011.0 |