編碼練習——Java-1-基礎__Ajax

歡迎訪問 部落格新址 基礎練習 輸出

public class MyApp {    public static void main(String[] args) {        System.out.println("我能學好Java語言。");    }}

整數類型

public class Test {    public static void main(String[] args) {        byte mybyte = 124;        short myshort = 32564;        int myint = 45784612;        long mylong = 46789451L;        long result = mybyte+myshort+myint+mylong;        System.out.println("四種類型相加的結果為："+result);    }}

浮點型

public class Test {    public static void main(String[] args) {        float f1 = 12.23f;        double d1 = 4562.12d;        double d2 = 45678.1564;        double result = f1+d1+d2;        System.out.println("浮點數相加達到結果為："+result);    }}

字元型

public class Test {    public static void main(String[] args) {        int i = 'd';        char c = 97;        System.out.println("字元d的Unicode碼是："+i);        System.out.println("Unicode碼97代表的字元是："+c);    }}

逸出字元

public class Test {    public static void main(String[] args) {        char char1 = '\\';        char char2 = '\u2605';        System.out.println("輸出反斜線：" + char1);        System.out.println("輸出五角星：" + char2);    }}

變數（聲明與定義）

public class Test {    public static void main(String[] args) {        int i= 10;        System.out.println("i的初值是："+i);        i= 100;        System.out.println("i現在的值是："+i);    }}

聲明常量
final 一般大寫

public class Test {    public static void main(String[] args) {        final double PI = 3.1415926F; // final 大寫        final boolean BOOL = true;    }}

變數和常量（靜態變數）

public class Test {    static final double PI = 3.14;    static int age = 23;    public static void main(String[] args) {        final int number;        number = 1235;        age = 22;        System.out.println("常量PI的值為："+PI);        System.out.println("賦值後number的值為："+number);        System.out.println("int型變數age的值為：" + age);    }}

成員變數（靜態變數）和局部變數

public class Test {    static int times = 3;    public static void main(String[] args) {        int times = 4;        System.out.println("times的值為：" + times);        System.out.println("times的值為：" + Test.times);    }}

賦值運算子

public class Test {    public static void main(String[] args) {        int a,b,c;        a = 15;        c = b = a+4;        System.out.println("c的值為：" + c);        System.out.println("b的值為：" + b);    }}

算術運算子

    public static void main(String[] args) {        float number1 = 45.56f;        int number2 = 152;        System.out.println("45.56f和152的和為：" + (number1+number2));        System.out.println("45.56f和152的差為：" + (number1-number2));        System.out.println("45.56f和152的積為：" + (number1*number2));        System.out.println("45.56f和152的商為：" + (number1/number2));    }}

關係運算子

public class Test {    public static void main(String[] args) {        int number1 = 4;        int number2 = 5;        System.out.println("4>5是否成立：" + (number1>number2));        System.out.println("4<5是否成立：" + (number1<number2));        System.out.println("4==5是否成立：" + (number1==number2));        System.out.println("4!=5是否成立：" + (number1!=number2));        System.out.println("4>=5是否成立：" + (number1>=number2));        System.out.println("4<=5是否成立：" + (number1<=number2));    }}

邏輯運算子

public class Test {    public static void main(String[] args) {        int a = 2;        int b = 5;        boolean result1 = ((a>b) && (a!=b));        boolean result2 = ((a>b) ||(a!=b));        System.out.println("(a>b) && (a!=b)的值是：" + result1);        System.out.println("(a>b) ||(a!=b)的值是：" + result2);    }}

按位元運算符

public class Test {    public static void main(String[] args) {        int i = 46;        int j = 97;        char c = 'a';        System.out.println("46 & 97 的值是：" + (i&j));        System.out.println("46 & 'a' 的值是：" + (i^c));        System.out.println("46 >>1  的值是：" + (i>>1));    }}

三元條件運算子

public class Test {    public static void main(String[] args) {        int i = 46;        int j = 97;        int z = i>j ? 100 : 200;        System.out.println("i>j?100:200 的值是：" + z);    }}

執行個體 - 不用其它變數實現兩個變數互換

import java.util.Scanner;public class Test {    public static void main(String[] args) {        Scanner scan = new Scanner(System.in);        System.out.println("請輸入變數A的值：\n");        long A = scan.nextLong();        System.out.println("請輸入變狼B的值：\n");        long B = scan.nextLong();        System.out.println("A="+A+"\tB="+B);        System.out.println("執行變數互換...");        A = A^B;        B = B^A;        A = A^B;        System.out.println("A="+A+"\tB="+B);    }}

執行個體 - 判斷數位奇偶性

import java.util.Scanner;public class Test {    public static void main(String[] args) {        Scanner scan = new Scanner(System.in);        System.out.println("請輸入一個整數：");        long number = scan.nextLong();        String check = (number%2 == 0) ? "這個數字是：偶數" : "這個數字是：奇數";        System.out.println(check);    }}

自動類型轉換

public class Test {    public static void main(String[] args) {        float number1 = 45f;        int number2 = 152;        System.out.println(number1+number2);    }}

public class Test {    public static void main(String[] args) {        byte mybyte = 127;        int myint = 150;        float myfloat = 452.12f;        char mychar = 10;        double mydouble = 45.46546;        //將運算結果輸出        System.out.println("127 + 452.12 = " + (mybyte+myfloat));        System.out.println("127*150 = " + (mybyte*myint));        System.out.println("127/10 = " + (mybyte/mychar));        System.out.println("45.46546+10 = " + (mydouble+mychar));    }}

強制類型轉換

public class Test {    public static void main(String[] args) {        int a = (int) 45.23;        long y = (long)456.6F;        int b = (int)'a';        System.out.println("a = " + a);        System.out.println("y = " + y);        System.out.println("b = " + b);    }}

執行個體 - 類型轉換

public class Test {    public static void main(String[] args) {        int intNum = 4;        float floatNum = 9.5F;        floatNum /= intNum; //自動類型轉換        System.out.println("9.5F/4 = " + floatNum);        double numX = 4.88;        double numY = 78.83;        int numZ = (int)numX + (int)numY; //強制類型轉換        System.out.println("4.88 + 78.83 = " + numZ);        char charVar = 'T';        int intVar = (int) charVar;        System.out.println("將字元T轉換成int型變數是：" + intVar);        int num1 = 34;        double num2 = (double) num1/3;        System.out.println("34的三分之一是："+num2);    }}

注釋
單行 多行 文檔注釋

public class Test {    public static void main(String[] args) {        // 單行注釋        /*         * 多行注釋1         * 多行注釋2         */        /**         * 文檔注釋         */    }}

執行個體 - 判斷某一年是否是閏年

import java.util.Scanner;public class Test {    public static void main(String[] args) {        Scanner scan = new Scanner(System.in);        System.out.println("請輸入一個年份：");        long year = scan.nextLong();        if(year%4==0 && year%100!=0 || year%400==0) {            System.out.println(year + "年是閏年。");        }else {            System.out.println(year + "年不是閏年。");        }    }}

執行個體 - 求球形的體積

import java.util.Scanner;public class Test {    public static void main(String[] args) {        Scanner scan = new Scanner(System.in);        System.out.println("請輸進球形的半徑：");        double r = scan.nextDouble();        final double PI = 3.1415926;        double volume = 4.0/3.0*PI*r*r*r;        System.out.println("球形的半徑是：" + r);        System.out.println("圓周率是：" + PI);        System.out.println("球形的體積是：" + volume);    }}

複合陳述式

public class Test {    public static void main(String[] args) {        int y = 40;        System.out.println("輸出y的值：" + y);        int z = 245;        boolean b;        // 複合陳述式        {            b = y>z;            System.out.println("y>z城裡嗎：" + b);        }    }}