java听课笔记(一小部分)

package lesson05;

public class TestExample13 {

public void testMethod() {

// 使用for循环完成将1到100的相加

int sum = 0;

for (int i = 1; i < 101; i++) {

sum = sum + i;

}

System.out.println(\"1~100相加后的和为：\" + sum);

}

public void testMethod1() {

// 使用while循环完成1到1000的相加

int i = 1;

int sum = 0;

while (i < 101) {

sum = sum + i;

i++;

}

System.out.println(\"1~100相加后的和为：\" + sum);

}

public void testMethod2() {

// 使用do...while循环完成1到100的相加

int i = 1;

int sum = 0;

do {

sum = sum + i;

i++;

} while (i < 101);

System.out.println(\"1~100相加后的和为：\" + sum);

}

public void testMethod3() {

// 使用For-Each循环完成1到100的输出

int tempArray[] = new int[100];

for (int i = 1; i < 101; i++) {

tempArray[i - 1] = i;

}

for (int k : tempArray) {

System.out.print(k + \" \");

}

}

public static void main(String[] args) {

TestExample13 te1 = new TestExample13();

te1.testMethod3();

}

}

package lesson05;

public class TestExample10 {

public void testMethod() {

int a = 10;

int b = 20;

if (((a - b) > b) || ((b - a) == b)) {

System.out.println(\"ok!\");

}

int c = 9999;

byte b1 = (byte)c; //精度的损失

System.out.println(b1);

float a1 = 3.1415926f;

int a2 = (int)a1;

System.out.println(a2);

double d = 'c';

System.out.println(d);

}

public static void main(String[] args) {

TestExample10 te1 = new TestExample10();

te1.testMethod();

}

}

package lesson05;

import java.util.Scanner;

public class TestExample11 {

public void testMethod() {

Scanner aa = new Scanner(System.in);

System.out.println(\"请输入你的性别(男/女):\");

String temp = aa.nextLine();

if (temp.equals(\"男\")) {

System.out.println(\"男生！\");

} else if (temp.equals(\"女\")) {

System.out.println(\"女生！\");

} else {

System.out.println(\"有没有搞错！\");

}

}

public void testMethod1() {

Scanner aa = new Scanner(System.in);

System.out.println(\"请输入星期<请使用英文缩写>:\");

String temp = aa.nextLine();

if (temp.equals(\"MON\")) {

System.out.println(\"星期一\");

} else if (temp.equals(\"TUE\")) {

System.out.println(\"星期二\");

} else if (temp.equals(\"WED\")) {

System.out.println(\"星期三\");

}else if (temp.equals(\"THU\")) {

System.out.println(\"星期四\");

}else if (temp.equals(\"FRI\")) {

System.out.println(\"星期五\");

}else if (temp.equals(\"SAT\")) {

System.out.println(\"星期六\");

}else {

System.out.println(\"星期日\");

}

}

public static void main(String[] args) {

TestExample11 te1 = new TestExample11();

te1.testMethod1();

}

}

package lesson05;

import java.util.Scanner;

public class TestExample12 {

public void testMethod() {

Scanner aa = new Scanner(System.in);

System.out.println(\"请输入1~7的数字表示星期：\");

int a = aa.nextInt();

switch (a) {

case 1:

System.out.println(\"星期一\");

break;

case 2:

System.out.println(\"星期二\");

break;

case 3:

System.out.println(\"星期三\");

break;

case 4:

System.out.println(\"星期四\");

break;

case 5:

System.out.println(\"星期五\");

break;

case 6:

System.out.println(\"星期六\");

break;

case 7:

System.out.println(\"星期日\");

break;

default:

System.out.println(\"错误！\");

}

}

public static void main(String[] args) {

// TODO Auto-generated method stub

TestExample12 te1 = new TestExample12();

te1.testMethod();

}

}