java array one-dimensional array

Definition of array:

Array is the simplest composite data type, which is a collection of ordered data of the same type. A data member in an array is called an array element and can be uniquely identified by a unified array name and subscript. Depending on whether the array subscript is one or multiple, arrays are divided into one-dimensional arrays and multi-dimensional arrays.

The general form of declaring a one-dimensional array is:

类型 数组名[ ]; 或 类型[ ] 数组名;

For example:

 int intArray[ ]; int[ ] intArray;

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Initialization of one-dimensional array:

类型 数组名[] = {元素1[,元素2…]}

For example:

int intArray[] = {1,2,3,4,5};
double decArray[] = {1.1,2.2,3.3};
String strArray[] = {“Java”,“BASIC”,“FORTRAN”};

Use new operator

If the array has been declared, the general form of allocating space for the declared array is as follows:

数组名= new 类型[数组大小];

If the array is not declared, you can use the new operator to allocate space for the array at the same time as the array is declared:

类型 数组名[] = new 类型[数组大小];

For example:

int a[]=new int[6];

(Note: Java performs out-of-bounds checks on array elements to ensure safety. If the array element subscript is less than 0, greater than or equal to the array length, an exception will be generated: ArrayIndexOutOfBoundsException.

For arrays, there is a frequently used length, which represents the length of the array.

For example:

int a[]=new int[10];

then:

a.length=10

)

Problems solved using arrays:

Find the average score of students

Assume that the student scores are: 80, 60, 90, 45, 100, 88, 59, 98

Example:

package 数组;

public class LY4求平均值 {

	public static void main(String[] args) {
		int[] a = { 80, 60, 90, 45, 100, 88, 59, 98 };
		double sum = 0, aver = 0;
		for (int b = 0; b < a.length; b++) {
			sum = sum + a[b];
		}
		aver = sum / a.length;
		System.out.println("学生的平均成绩为:" + aver);

	}

}

The running result is:

The average score of students is:77.5

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