Prefacio:
¡Registre la expansión y contracción de la matriz!
Expansión:
La matriz existente int[] arr = new int[]{1,2,3,4,5} necesita duplicar la longitud de la matriz y agregar los datos 10, 20 y 30 a la matriz arr.
Hay dos formas de escribir el doble de la capacidad.
int[] newArr = new int[arr.length * 2];
//或是
int[] newArr = new int[arr.length << 1];int[] arr = {1, 2, 3, 4, 5};
int[] newArr = new int[arr.length << 1]; //new int[arr.length * 2];
for (int i = 0; i < arr.length; i++) {
newArr[i] = arr[i];
}
newArr[arr.length] = 10;
newArr[arr.length + 1] = 20;
newArr[arr.length + 2] = 30;
System.out.println(Arrays.toString(newArr)); //[1, 2, 3, 4, 5, 10, 20, 30, 0, 0]Contracción:
Matriz existente int[] arr = {1,2,3,4,5,6,7}. Ahora debe eliminar el elemento con índice 4 en la matriz, es decir, 5, para obtener [1,2,3,4,6,7]
La primera:
int[] array = {1, 2, 3, 4, 5, 6, 7};
int deleteIndex = 4;
for (int i = deleteIndex; i < array.length - 1; i++) {
array[i] = array[i + 1];
}
array[array.length - 1] = 0;
int[] newArray = new int[array.length - 1];
for (int i = 0; i < newArray.length; i++) {
newArray[i] = array[i];
}
array = newArray;
System.out.println(Arrays.toString(array)); //[1, 2, 3, 4, 6, 7]El segundo tipo:
int[] array = {1, 2, 3, 4, 5, 6, 7};
int deleteIndex = 4;
int[] newArray = new int[array.length - 1];
for (int i = 0; i < deleteIndex; i++) {
newArray[i] = array[i];
}
for (int i = deleteIndex; i < array.length - 1; i++) {
newArray[i] = array[i + 1];
}
array = newArray;
System.out.println(Arrays.toString(array));