这是indexloc提供的服务，不要输入任何密码
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Jul 29, 2025
Merged

https://jira.baeldung.com/browse/BAEL-9394 #18706

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51 changes: 47 additions & 4 deletions ...-java-arrays-multidimensional/src/main/java/com/baeldung/array/MultiDimensionalArray.java
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Original file line number Diff line number Diff line change
Expand Up @@ -18,15 +18,49 @@ int[][] declarationAndThenInitialization() {
return multiDimensionalArray;
}

int[][] declarationAndThenInitializationBaseOnIndex() {
int[][] multiDimensionalArray = new int[3][];
multiDimensionalArray[0] = new int[2];
multiDimensionalArray[1] = new int[3];
multiDimensionalArray[2] = new int[4];

multiDimensionalArray[0][0] = 1;
multiDimensionalArray[0][1] = 2;

multiDimensionalArray[1][0] = 3;
multiDimensionalArray[1][1] = 4;
multiDimensionalArray[1][2] = 5;

multiDimensionalArray[2][0] = 6;
multiDimensionalArray[2][1] = 7;
multiDimensionalArray[2][2] = 8;
multiDimensionalArray[2][3] = 9;

return multiDimensionalArray;
}

int[][] declarationAndThenInitializationUsingUserInputs() {
int[][] multiDimensionalArray = new int[3][];
multiDimensionalArray[0] = new int[2];
multiDimensionalArray[1] = new int[3];
multiDimensionalArray[2] = new int[4];

initializeElements(multiDimensionalArray);
return multiDimensionalArray;
}

int[][] declarationAndThenInitializationFirstAlternative() {
int[][] multiDimensionalArray = new int[][] { new int[] { 1, 2 }, new int[] { 3, 4, 5 }, new int[] { 6, 7, 8, 9 } };

return multiDimensionalArray;
}

int[][] declarationAndThenInitializationSecondAlternative() {
int[][] multiDimensionalArray = { new int[] { 1, 2 }, new int[] { 3, 4, 5 }, new int[] { 6, 7, 8, 9 } };

return multiDimensionalArray;
}

void initializeElements(int[][] multiDimensionalArray) {
Scanner sc = new Scanner(System.in);
for (int outer = 0; outer < multiDimensionalArray.length; outer++) {
Expand All @@ -48,6 +82,15 @@ void printElements(int[][] multiDimensionalArray) {
}
}

void printElementsUsingNestedForLoop(int[][] multiDimensionalArray) {
for (int i = 0; i < multiDimensionalArray.length; i++) {
for (int j = 0; j < multiDimensionalArray[i].length; j++) {
System.out.print(multiDimensionalArray[i][j] + " ");
}
System.out.println();
}
}

int[] getElementAtGivenIndex(int[][] multiDimensionalArray, int index) {
return multiDimensionalArray[index];
}
Expand All @@ -62,8 +105,8 @@ int[] findLengthOfElements(int[][] multiDimensionalArray) {

Integer[] findLengthOfElements(Integer[][] multiDimensionalArray) {
return Arrays.stream(multiDimensionalArray)
.map(array -> array.length)
.toArray(Integer[]::new);
.map(array -> array.length)
.toArray(Integer[]::new);
}

int[][] copy2DArray(int[][] arrayOfArrays) {
Expand All @@ -77,7 +120,7 @@ int[][] copy2DArray(int[][] arrayOfArrays) {

Integer[][] copy2DArray(Integer[][] arrayOfArrays) {
return Arrays.stream(arrayOfArrays)
.map(array -> Arrays.copyOf(array, array.length))
.toArray(Integer[][]::new);
.map(array -> Arrays.copyOf(array, array.length))
.toArray(Integer[][]::new);
}
}
30 changes: 22 additions & 8 deletions ...rays-multidimensional/src/test/java/com/baeldung/array/MultiDimensionalArrayUnitTest.java
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Expand Up @@ -46,7 +46,21 @@ public void givenMultiDimensionalArray_whenUsingArraysAPI_thenVerifyPrintedEleme
ByteArrayOutputStream outContent = new ByteArrayOutputStream();
System.setOut(new PrintStream(outContent));
obj.printElements(multiDimensionalArr);
assertEquals("[1, 2][3, 4, 5][6, 7, 8, 9]", outContent.toString().replace("\r", "").replace("\n", ""));
assertEquals("[1, 2][3, 4, 5][6, 7, 8, 9]", outContent.toString()
.replace("\r", "")
.replace("\n", ""));
System.setOut(System.out);
}

@Test
public void givenMultiDimensionalArray_whenUsingNestedForLoopToPrint_thenVerifyPrintedElements() {
int[][] multiDimensionalArr = { { 1, 2 }, { 3, 4, 5 }, { 6, 7, 8, 9 } };
ByteArrayOutputStream outContent = new ByteArrayOutputStream();
System.setOut(new PrintStream(outContent));
obj.printElementsUsingNestedForLoop(multiDimensionalArr);
assertEquals("1 2 3 4 5 6 7 8 9 ", outContent.toString()
.replace("\r", "")
.replace("\n", ""));
System.setOut(System.out);
}

Expand All @@ -57,27 +71,27 @@ public void givenMultiDimensionalArray_whenUsingArraysFill_thenVerifyInitialize2
multiDimensionalArr[1] = new int[3];
multiDimensionalArr[2] = new int[4];
obj.initialize2DArray(multiDimensionalArr);
assertArrayEquals(new int[][] {{7,7}, {7,7,7}, {7,7,7,7}}, multiDimensionalArr);
assertArrayEquals(new int[][] { { 7, 7 }, { 7, 7, 7 }, { 7, 7, 7, 7 } }, multiDimensionalArr);
}

@Test
public void givenMultiDimensionalArray_whenUsingIteration_thenVerifyFindLengthOfElements() {
int[][] multiDimensionalArr = { { 1, 2 }, { 3, 4, 5 }, { 6, 7, 8, 9 } };
assertArrayEquals(new int[]{2,3,4}, obj.findLengthOfElements(multiDimensionalArr));
assertArrayEquals(new int[] { 2, 3, 4 }, obj.findLengthOfElements(multiDimensionalArr));
}

@Test
public void givenMultiDimensionalArray_whenUsingArraysStream_thenVerifyFindLengthOfElements() {
Integer[][] multiDimensionalArr = { { 1, 2 }, { 3, 4, 5 }, { 6, 7, 8, 9 } };
assertArrayEquals(new Integer[]{2,3,4}, obj.findLengthOfElements(multiDimensionalArr));
assertArrayEquals(new Integer[] { 2, 3, 4 }, obj.findLengthOfElements(multiDimensionalArr));
}

@Test
public void givenMultiDimensionalArray_whenUsingArraysCopyOf_thenVerifyCopy2DArray() {
int[][] multiDimensionalArr = { { 1, 2 }, { 3, 4, 5 }, { 6, 7, 8, 9 } };
assertArrayEquals(multiDimensionalArr, obj.copy2DArray(multiDimensionalArr));
}

@Test
public void givenMultiDimensionalArray_whenUsingArraysStream_thenVerifyCopy2DArray() {
Integer[][] multiDimensionalArr = { { 1, 2 }, { 3, 4, 5 }, { 6, 7, 8, 9 } };
Expand Down