For循环
练习一：计算0-100之间的偶数与奇数之和分别是？
public class ForDemo01 {
public static void main(String[] args) {
int evenSum = 0;//偶数
int oddSum = 0;//奇数
for (int i = 0; i <= 100; i++) {
if(i%2 == 0){
evenSum = evenSum + i;
} else{
oddSum = oddSum + i;
}
}
System.out.println("偶数之和是：" + evenSum);
System.out.println("奇数之和是：" + oddSum);
}
}
结果是：
练习二：输出1-1000之间能被5整除，并且每输出3个进行换行。
public class ForDemo02 {
public static void main(String[] args) {
for (int i = 1; i <= 1000; i++) {
if(i%5 == 0){
System.out.print(i + "\t");
}
if(i%(5*3)==0){
System.out.println();
//System.out.println("\n");
}
}
}
}
结果为：后面截图省略
练习三：打印九九乘法表
public class ForDemo03 {
public static void main(String[] args) {
for (int i = 1; i <= 9; i++) {
for (int j = 1; j <= i; j++) {
System.out.print(j + "*" + i + "=" + (i*j)+"\t");
}
System.out.println();
}
}
}
结果为：
练习四：了解增强For循环
public class ForDemo04 {
public static void main(String[] args) {
int[] number = {10,20,30,40};
for (int i = 0; i < 4; i++) {
System.out.println(number[i]);
}
System.out.println("============");
for(int x:number){
System.out.println(x);
}
}
}
结果为：
练习五：打印三角形
public class TestDemo01 {
public static void main(String[] args) {
for (int i = 1; i <= 5; i++) {
for (int j = 5; j >= i; j--) {
System.out.print(" ");
}
for (int j = 1; j <= i; j++) {
System.out.print("*");
}
for (int j = 1; j < i; j++) {
System.out.print("*");
}
System.out.println();
}
}
}
结果为：
练习六：编写一个简单的计算机（未改进）
package struct;
import java.util.Scanner;
public class Calculator {
public static void main(String[] args) {
Calculator cal = new Calculator();
System.out.println("请输入第一个数字：");
Scanner sc = new Scanner(System.in);
System.out.println("请输入第二个数字：");
Scanner sc1 = new Scanner(System.in);
System.out.println("请选择要进行的运算：");
Scanner sc2 = new Scanner(System.in);
int num = sc.nextInt();
int num1 = sc1.nextInt();
int num2 = sc2.nextInt();
switch (num2){
case 0:
System.out.println(cal.add(num,num1));
break;
case 1:
System.out.println(cal.sub(num,num1));
break;
case 2:
System.out.println(cal.mul(num,num1));
break;
case 3:
System.out.println(cal.mod(num,num1));
break;
default:
System.out.println("输入有误！！！");
}
sc.close();
sc1.close();
sc2.close();
}
public static int add(int x,int y){
int sum = 0;
sum = x + y;
return sum;
}
public static int sub(int x,int y){
return x-y;
}
public static int mul(int x,int y){
return x*y;
}
public static int mod(int x,int y){
return (int)x/y;
}
}
