萬年歷
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隨機生成時期雙色球中獎號碼
import java.util.Random;
public class xxx {
public static void main(String[] args) {
Random random = new Random();
int[][] arr = new int[10][7];
for (int i = 0; i < arr.length; i++) {
for (int j = 0; j < arr[i].length; j++) {
arr[i][j] = random.nextInt(33) + 1;
if (j == 6) {
arr[i][j] = random.nextInt(16) + 1;
}
}
}
for (int i = 0; i < arr.length; i++) {
System.out.print("第" + (i + 1) + "期中獎號碼\t");
for (int j = 0; j < arr[i].length; j++) {
System.out.print(arr[i][j] + "\t\t");
}
System.out.print("\n");
}
}
}
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用函數調用將計算器功能實現
import java.util.Scanner;
public class Calculator{
public static void main(String[] args) {
Scanner scan = new Scanner(System.in);
System.out.println("請輸入第一個數:");
int num1 = scan.nextInt();
System.out.println("請輸入第二個數:");
int num2 = scan.nextInt();
System.out.println("請輸入運算符:1+,2*,3/,4-");
int operator = scan.nextInt();
switch (operator) {
case 1:
int result = add(num1, num2);
System.out.print("result:" + result);
break;
case 2:
int result1 = mul(num1, num2);
System.out.print("result:" + result1);
break;
case 3:
double result2 = div(num1, num2);
System.out.print("result:" + result2);
break;
case 4:
int result3 = sub(num1, num2);
System.out.print("result:" + result3);
break;
}
return ;
}
/**
*
* @param num1 第一個操作數
* @param num2 第二個操作數
* @return 當傳入兩個操作數時返回兩個操作數的和,返回值用於主方法中輸出結果
*/
public static int add(int num1, int num2) {
return num1 + num2;
}
public static int mul(int num1, int num2) {
return num1 * num2;
}
public static double div(double num1, double num2) {
return num1 / num2;
}
public static int sub(int num1, int num2) {
return num1 - num2;
}
}
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調用函數時傳入基本數據類型,不會改變傳入的變量值.
但是傳入數組時(引用數據類型),會改變傳入的數組的值
函數重載：
* 有參和無參
* 同為有參但是參數的數量不一致
* 同為有參但是參數的類型不一致
* 同為有參當類型和數量一致,但是順序不一致時也是重載.
public static void main(String[] args) {
int a = 10;
int b = 20;
System.out.println("a:"+a+",b:"+b);
change(a,b);
System.out.println("a:"+a+",b:"+b);
int[] arr = {1,2,3,4,5};
change(arr);
System.out.println(arr[1]);
}
//以下change方法重載
public static void change(int a,int b) {
System.out.println("a:"+a+",b:"+b);
a = b;
b = a + b;
System.out.println("a:"+a+",b:"+b);
}
public static void change(int[] arr) {
for(int x=0; x<arr.length; x++) {
if(arr[x]%2==0) {
arr[x]*=2;
}
}
}