1、编写一个简单程序,要求数组长度为5,分别赋值10,20,30,40,50,在控制台输出该数组的值.
package work; public class work { public static void main(String[] args) { int a[]={10,20,30,40,50}; for (int i = 0; i < a.length; i++) { System.out.println(a[i]); } } }
2、将一个字符数组的值(neusofteducation)拷贝到另一个字符数组中。
package work; public class work { public static void main(String[] args) { char a[]={'n','e','u','s','o','f','t','e','d','u','c','a','t','i','o','n'}; char[]b=new char[16]; System.arraycopy(a, 0, b, 0, 16); for (int i = 0; i < a.length; i++) { System.out.print(a[i]); } } }
3、给定一个有9个整数(1,6,2,3,9,4,5,7,8)的数组,先排序,然后输出排序后的数组的值。
Arrays.sort排序:
package work; import java.util.Arrays; public class work { public static void main(String[] args) { int a[]={1,6,2,3,9,4,5,7,8}; Arrays.sort(a); System.out.println("排序后"); for (int i = 0; i < a.length; i++) { System.out.print(" "+a[i]); } } }
冒泡排序:
package work; import java.util.Arrays; public class work { public static void main(String[] args) { int a[]={1,6,2,3,9,4,5,7,8}; for (int i = 0; i < a.length-1; i++) { for (int j = 0; j < a.length-1-i; j++) { if (a[j]>a[j+1]) { int temp=a[j]; a[j]=a[j+1]; a[j+1]=temp; } } } System.out.println("排序后"); for (int i = 0; i < a.length; i++) { System.out.print(" "+a[i]); } } }
4、 输出一个double型二维数组(长度分别为5、4,值自己设定)的值。(知识点:数组定义和创建、多维数组初始化、数组遍历)
package work; public class work { public static void main(String[] args) { double [][]a=new double[5][4]; for (int i = 0; i < a.length; i++) { for (int j = 0; j < a[i].length; j++) { a[i][j]=j; System.out.print(a[i][j]+" "); }System.out.println(); } } }
5、 在一个有8个整数(18,25,7,36,13,2,89,63)的数组中找出其中最大的数及其下标。(知识点:数组遍历、数组元素访问) [必做题]•
package work; public class work { public static void main(String[] args) { int a[]={18,25,7,36,13,2,89,63}; int max=a[0]; int index=0; for (int i = 0; i < a.length; i++) { if (a[i]>max) { max=a[i]; index=i; } } System.out.println("数组中的最大值为"+max); System.out.println("下标为"+index); } }
作业
6、将一个数组中的元素逆序存放(知识点:数组遍历、数组元素访问) [选作题]•
package work; public class work { public static void main(String[] args) { int a[]={18,25,7,36,13,2,89,63}; System.out.println("倒序后为:"); for (int i = 7; i >= 0; i--) { System.out.print (" "+a[i]); } } }
7. 将一个数组中的重复元素保留一个其他的清零。(知识点:数组遍历、数组元素访问)
package work; public class work { public static void main(String[] args) { int a[]={18,25,7,36,13,2,89,63,25,18}; for (int i = 0; i < a.length; i++) { for (int j = 0; j < a.length; j++) { if (a[i]==a[j] && i!=j) { a[j]=0; } } } for (int i : a) { System.out.print(" "+i); } } }
8、给定一维数组{ -10,2,3,246,-100,0,5},计算出数组中的平均值、最大值、最小值。(知识点:数组遍历、数组元素访问)
package work; public class work { public static void main(String[] args) { int a[]={-10,2,3,246,-100,0,5}; int max=a[0]; int min=a[0]; double sum=0; for (int i = 0; i < a.length; i++) { if (max<a[i]) { max=a[i]; } if (min>a[i]) { min=a[i]; } sum+=a[i]; } sum=sum/7; System.out.println("最大值"+max); System.out.println("最小值"+min); System.out.println("平均值"+sum); }
}
9、使用数组存放裴波那契数列的前20项 ,并输出 1 1 2 3 5 8 13 21
package work; public class work { public static void main(String[] args) { int[] a = new int[20]; a[0] = 1; a[1] = 1; for (int i = 2; i < a.length; i++) { a[i] = a[i - 1] + a[i - 2]; } for (int i = 0; i < 8; i++) { System.out.print(a[i] + " "); } } }
10、生成一个长度为10的随机整数数组(每个数都是0-100之间),输出,排序后,再输出
package work; import java.util.Arrays; import java.util.Random; public class work { public static void main(String[] args) { Random r = new Random(); int a[] = new int[10]; for (int i = 0; i < a.length; i++) { a[i] = r.nextInt(101); } for (int i = 0; i < a.length; i++) { System.out.print(a[i] + " "); } Arrays.sort(a); System.out.println(); for (int i = 0; i < a.length; i++) { System.out.print(a[i]+" "); } } }