BAEL-1250 Initializing Arrays in Java (#2811)
* Evaluation article: Different Types of Bean Injection in Spring * added tests & changed configuration to Java-based config * removed xml config files * rename unit tests * BAEL-972 - Apache Commons Text * remove code from evaluation article * remove code from evaluation article * BAEL-972 - Apache Commons Text - added another example * BAEL-972 - Apache Commons Text - just indentation * BAEL-994 - TemporalAdjuster in Java * BAEL-994 - TemporalAdjuster in Java * BAEL-994 - TemporalAdjuster in Java * BAEL-994 - TemporalAdjuster in Java * BAEL-994 - TemporalAdjuster in Java - fix problems * BAEL-1033 Introduction to StreamUtils * BAEL-1033 Introduction to StreamUtils * BAEL-1033 Introduction to StreamUtils * fix formatting * BAEL-1033 minor refactor * BAEL-1035 Introduction to Eclipse Collections * format * BAEL-1035 Introduction to Eclipse Collections * BAEL-1035 Introduction to Eclipse Collections * BAEL-1035 Introduction to Eclipse Collections * cleanup * cleanup * BAEL-1109 Introduction to JCache * BAEL-1109 Introduction to JCache * remove unneeded property in pom.xml * fix formatting * close cache instances properly * remove latest commit * BAEL-1057 Introduction to rxjava-jdbc * refactor rxjava-jdbc * Refactor rxjava-jdbc * Refactoring rxjava-jdbc * BAEL-1171 java.lang.String API * refactor rxjava-jdbc * refactor String * String API - move multiple classes into a single class * move class into test package * BAEL-1171 String.lang.String API * BAEL-1171 java.lang.String API * BAEL-1250 Initializing Arrays in Java * BAEL-1250 Initializing Arrays in Java
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package com.baeldung.array;
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import java.util.Arrays;
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public class ArrayInitializer {
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public static int[] initializeArrayInLoop() {
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int array[] = new int[5];
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for (int i = 0; i < array.length; i++)
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array[i] = i + 2;
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return array;
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}
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public static int[][] initializeMultiDimensionalArrayInLoop() {
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int array[][] = new int[2][5];
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for (int i = 0; i < 2; i++)
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for (int j = 0; j < 5; j++)
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array[i][j] = j + 1;
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return array;
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}
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public static String[] initializeArrayAtTimeOfDeclarationMethod1() {
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String array[] = new String[] { "Toyota", "Mercedes", "BMW", "Volkswagen", "Skoda" };
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return array;
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}
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public static int[] initializeArrayAtTimeOfDeclarationMethod2() {
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int[] array = new int[] { 1, 2, 3, 4, 5 };
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return array;
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}
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public static int[] initializeArrayAtTimeOfDeclarationMethod3() {
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int array[] = { 1, 2, 3, 4, 5 };
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return array;
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}
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public static long[] initializeArrayUsingArraysFill() {
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long array[] = new long[5];
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Arrays.fill(array, 30);
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return array;
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}
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public static int[] initializeArrayRangeUsingArraysFill() {
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int array[] = new int[5];
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Arrays.fill(array, 0, 3, -50);
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return array;
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}
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public static int[] initializeArrayUsingArraysCopy() {
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int array[] = { 1, 2, 3, 4, 5 };
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int[] copy = Arrays.copyOf(array, 5);
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return copy;
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}
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public static int[] initializeLargerArrayUsingArraysCopy() {
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int array[] = { 1, 2, 3, 4, 5 };
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int[] copy = Arrays.copyOf(array, 6);
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return copy;
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}
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public static int[] initializeArrayUsingArraysSetAll() {
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int[] array = new int[20];
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for (int i = 0; i < 20; i++) {
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Arrays.setAll(array, p -> {
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if (p > 9)
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return 0;
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else
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return p;
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});
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}
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return array;
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}
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}
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package com.baeldung.array;
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import static com.baeldung.array.ArrayInitializer.initializeArrayAtTimeOfDeclarationMethod1;
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import static com.baeldung.array.ArrayInitializer.initializeArrayAtTimeOfDeclarationMethod2;
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import static com.baeldung.array.ArrayInitializer.initializeArrayAtTimeOfDeclarationMethod3;
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import static com.baeldung.array.ArrayInitializer.initializeArrayInLoop;
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import static com.baeldung.array.ArrayInitializer.initializeArrayRangeUsingArraysFill;
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import static com.baeldung.array.ArrayInitializer.initializeArrayUsingArraysCopy;
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import static com.baeldung.array.ArrayInitializer.initializeArrayUsingArraysFill;
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import static com.baeldung.array.ArrayInitializer.initializeArrayUsingArraysSetAll;
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import static com.baeldung.array.ArrayInitializer.initializeLargerArrayUsingArraysCopy;
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import static com.baeldung.array.ArrayInitializer.initializeMultiDimensionalArrayInLoop;
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import static org.junit.Assert.assertArrayEquals;
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import org.junit.Test;
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public class ArrayInitializerTest {
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@Test
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public void whenInitializeArrayInLoop_thenCorrect() {
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assertArrayEquals(new int[] { 2, 3, 4, 5, 6 }, initializeArrayInLoop());
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}
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@Test
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public void whenInitializeMultiDimensionalArrayInLoop_thenCorrect() {
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assertArrayEquals(new int[][] { { 1, 2, 3, 4, 5 }, { 1, 2, 3, 4, 5 } }, initializeMultiDimensionalArrayInLoop());
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}
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@Test
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public void whenInitializeArrayAtTimeOfDeclarationMethod1_thenCorrect() {
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assertArrayEquals(new String[] { "Toyota", "Mercedes", "BMW", "Volkswagen", "Skoda" }, initializeArrayAtTimeOfDeclarationMethod1());
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}
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@Test
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public void whenInitializeArrayAtTimeOfDeclarationMethod2_thenCorrect() {
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assertArrayEquals(new int[] { 1, 2, 3, 4, 5 }, initializeArrayAtTimeOfDeclarationMethod2());
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}
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@Test
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public void whenInitializeArrayAtTimeOfDeclarationMethod3_thenCorrect() {
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assertArrayEquals(new int[] { 1, 2, 3, 4, 5 }, initializeArrayAtTimeOfDeclarationMethod3());
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}
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@Test
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public void whenInitializeArrayUsingArraysFill_thenCorrect() {
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assertArrayEquals(new long[] { 30, 30, 30, 30, 30 }, initializeArrayUsingArraysFill());
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}
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@Test
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public void whenInitializeArrayRangeUsingArraysFill_thenCorrect() {
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assertArrayEquals(new int[] { -50, -50, -50, 0, 0 }, initializeArrayRangeUsingArraysFill());
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}
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@Test
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public void whenInitializeArrayRangeUsingArraysCopy_thenCorrect() {
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assertArrayEquals(new int[] { 1, 2, 3, 4, 5 }, initializeArrayUsingArraysCopy());
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}
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@Test
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public void whenInitializeLargerArrayRangeUsingArraysCopy_thenCorrect() {
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assertArrayEquals(new int[] { 1, 2, 3, 4, 5, 0 }, initializeLargerArrayUsingArraysCopy());
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}
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@Test
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public void whenInitializeLargerArrayRangeUsingArraysSetAll_thenCorrect() {
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assertArrayEquals(new int[] { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }, initializeArrayUsingArraysSetAll());
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}
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}
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