學習Java也快10天了，我的以爲學習過程有點枯燥，本身的效率也有點低。把本身作過的做業記錄下來，算是鞭策本身吧。java
做業1 從1加到100：
public class HomeWork {
public static void main(String[] args ) {
int n = 100;
int sum = ((1 + n) * n) / 2;
System.out.println(sum);
System.out.println(sum == 5050 ? "pass" : "faild"); //A ? B : C if A = T,run B;else run C
}
}
做業2 計算成績增加率：
import java.util.Scanner;
public class HomeWork {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
System.out.print("Input your new grade: ");
int grade_new = scanner.nextInt();
System.out.print("Input your last grade: ");
int grade_last = scanner.nextInt();
int grade_diff = grade_new - grade_last;
System.out.println(grade_diff);
float grade_pcent = (float)grade_diff / (float)grade_last;
System.out.println(grade_pcent);
double incre_pcent = grade_pcent * 100.00;
System.out.println(incre_pcent);
System.out.printf("Your grade increase percentage is %.2f%%.", incre_pcent);
scanner.close();
}
}
做業3 計算體重BIM同時判斷身體狀態：
import java.util.Scanner;
public class HomeWork {
public static void main(String[] args) {
System.out.print("Please enter your weight in Kg:");
Scanner scanner = new Scanner(System.in);
float weight = scanner.nextFloat();
System.out.print("Please enter your height in m:");
float height = scanner.nextFloat();
float BMI = weight / (height * height);
System.out.printf("Your BMI is:%.2f.\n", BMI);
if (BMI < 18.5) {
System.out.println("You are underweight.");
} else if (BMI >= 18.5 && BMI < 25) {
System.out.println("Your weight is normal.");
} else if (BMI >= 25 && BMI < 28) {
System.out.println("You are overweight.");
} else if (BMI >= 28 && BMI < 32) {
System.out.println("You are at risk for obesity.");
} else {
System.out.println("Watch out!" + "You are seriously overweight!");
}
scanner.close();
}
}
做業4 「剪刀石頭布」遊戲：
import java.util.Scanner;
/*
* Switch Multiple choices - Rock-paper-scissors game
*/
public class Game {
public static void main(String[] args) {
System.out.println("Please select:");
System.out.println("1:Rock");
System.out.println("2:Scissors");
System.out.println("3:Paper");
Scanner scanner = new Scanner(System.in);
int choice = 0;
int random = 1 + (int) (Math.random() * 3);
System.out.println("Tell me your choice:");
choice = scanner.nextInt();
switch (choice) {
case 1:
if (random == 1) {
System.out.println("Uh-oh, it's a tie game.");
} else if (random == 2) {
System.out.println("You win!");
} else {
System.out.println("Sorry, You loose.");
}
break;
case 2:
if (random == 1) {
System.out.println("Sorry, You loose.");
} else if (random == 2) {
System.out.println("YUh-oh, it's a tie game.");
} else {
System.out.println("You win!");
}
break;
case 3:
if (random == 1) {
System.out.println("You win!");
} else if (random == 2) {
System.out.println("Sorry, You loose.");
} else {
System.out.println("YUh-oh, it's a tie game.");
}
break;
default:
System.out.println("Pleas choice again.");
break;
}
if (random == 1) {
System.out.println("Your opponent chooses the Rock.");
} else if (random == 2) {
System.out.println("Your opponent chooses the Scissors.");
} else {
System.out.println("Your opponent chooses the Paper.");
}
scanner.close();
}
}
做業5 while循環求和：
/*
* While loop exercise
*/
public class HomeWork {
public static void main(String[] args) {
int sum = 0;
int m = 20;
int n = 100;
while(m<=n) {
sum = sum + m;
m++;
}
System.out.println(sum);
}
}
做業6 do while循環求和：
/*
* do while loop exercise
*/
public class HomeWork {
public static void main(String[] args) {
int sum = 0;
int m = 20;
int n = 100;
do {
sum = sum + m;
m++;
} while (m <= n);
System.out.println(sum);
}
}
做業7 倒敘輸出數組：
/*
* if loop exercise1
*/
public class HomeWork {
public static void main(String[] args) {
int[] ns = {1, 4, 9 ,16,25};
for (int i = 4; i >= 0; i--) {
System.out.println(ns[i]);
}
}
}
做業8 for循環練習2：
/*
* for loop exercise2
*/
public class HomeWork {
public static void main(String[] args) {
int[] ns = {1, 4, 9, 16, 25};
int sum = 0;
for (int n : ns) {
sum = sum + n;
}
System.out.println(sum);
}
}
做業9 計算圓周率（for循環練習3）：
/*
* for loop exercise3
*/
public class HomWork {
public static void main(String[] args) {
double pi = 0;
double n = 1;
for (int i = 1; i <= 9999999; i = i + 2) {
pi = pi + Math.pow(-1.0, n-1) * (4 / (double)i);
n++;
}
System.out.printf("%.10f", pi);
}
}
做業10 類練習：
public class ClassCity {
public static void main(String[] args) {
City bj = new City();
bj.name = "BeiJing";
bj.latitude = 39.903;
bj.longitude = 116.401;
System.out.println(bj.name);
System.out.println("location: " + bj.latitude + ", " + bj.longitude);
}
}
class City {
public String name;
public double latitude;
public double longitude;
}
做業11 類中方法練習：
public class HomeWork {
public static void main(String[] args) {
Person ming = new Person();
ming.setName("Xiao Ming");
ming.setAge(15);
System.out.println(ming.getName());
System.out.println(ming.getAge());
}
}
class Person {
private String name;
private int age;
public String getName() {
return name;
}
public int getAge() {
return age;
}
public void setName(String name) {
this.name = name;
}
public void setAge(int age) {
this.age = age;
}
}
做業12 類中方法練習2：
public class HomeWork {
public static void main(String[] args) {
Person ming = new Person("Xiao Ming", 12);
System.out.println(ming.getName());
System.out.println(ming.getAge());
}
}
class Person {
private String name;
private int age;
public Person(String name, int age) {
this.name = name;
this.age = age;
}
public String getName() {
return name;
}
public int getAge() {
return age;
}
}
做業13 方法重載練習：
/*
* exercise of overload
*/
public class HomeWork {
public static void main(String[] args) {
Person ming = new Person();
Person hong = new Person();
ming.setName("Xiao Ming");
hong.setName("Xaio", "Hong");
System.out.println(ming.getName());
System.out.println(hong.getName());
}
}
class Person {
private String name;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public void setName(String firstname, String lastname) {
this.name = firstname + " " + lastname;
}
}