JAVA范例 二）Java基础类型与运算符
实例2? 自动提升
public class BasicTypeChange{//创建一个修饰基本数据类型转换的类public static void main(String[] args) {byte b = 12;char c = 'b';short s = 13;int i = 567;long l = 678756;float ft = 23.67f;double db = 6.124d;//result声明为其他类型会出错，除非进行类型转换double result = (ft * b) + +(l * ft) + (i / c) - (db * s); System.out.print(" 结果 ：" + result+" = ");System.out.println((ft * b) + " + " + (l * ft) + " + " + (i / c) + " - "+ (db * s));//输入经过运算获得的结果}}
实例3? 自动转换
public class BasicAutoChange {// 基本类型的自动转换public static void main(String[] args) { char c = 'a';byte b = 44;short s0 = b;int i0 = s0;int i1 = c;long l = i0;float f = l;double d = f;float fl = 1.7f;double db = fl;System.out.println("fl = " + fl + "; dou = " + db);// 一个数从一种类型转换成另外一种类型，再转换回来时，值还是一样。fl = (float) db;System.out.println("fl = " + fl + "; dou = " + db);}}
实例4? 常用基础类型之强制转换
public class BasicForceChange {public static void main(String[] args) { // 基本类型的强制转换double db = 143.426d;float f = (float) db;//将double类型强转成floatlong l = (long) db;//将double类型强转成longint i = (int) db;//将double类型强转成intshort s = (short) db;//将double类型强转成shortbyte b = (byte) db;//将double类型强转成byteSystem.out.print("d = " + db + "; f = " + f + "; l = " + l);System.out.println("; i = " + i + "; s = " + s + "; b = " + b);db = 5127.87d;// 下面的转换进行截断操作b = (byte) db;System.out.println("d = " + db + "; b = " + b);}}?
?实例5? 算术运算符
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public class OperatorSign {public static void main(String[] args) {int a = 3, b = 4;int intA = a / b; // 根据基本类型自动转换规则，除数与被除数都是整数，float intB = a / b;float intC = a / (b * 2.0f); // 对于声明为float类型的数字，数字后加f,double intD = a / (b * 2.0d); // 对于声明为double类型的数字，数字后加d.int a1 = 10;int b1 = 3;double c = 2;System.out.println("(intA=a/b),intA=" + intA);System.out.println("(intB=a/b),intB=" + intB);System.out.println("(intC=a/(b*2.0f)),intC=" + intC);System.out.println("(intD=a/(b*2.0d)),intD=" + intD);System.out.println(a1 + "/" + b1 + "=" + (a1 / b1));System.out.println(a1 + "%" + b1 + "=" + (a1 % b1));System.out.println(a1 + "/" + c + "=" + (a1 / c));System.out.println(a1 + "%" + c + "=" + (a1 % c));int x = 12;int a2 = x + x++; //定义一个自增的变量System.out.println("a2=" + a2);System.out.println("x=" + x);int b2 = x++ + x;System.out.println("b2=" + b2);System.out.println("x=" + x);int c2 = x + x--;//定义一个自减的变量System.out.println("c2=" + c2);System.out.println("x=" + x);int d = x + --x;System.out.println("d=" + d);System.out.println("x=" + x);}}?
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实例6? 关系运算符
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public class RelationTest {public static void main(String[] args) {boolean i,j,k,x, y, z; //定义6个布尔型的常量int a = 11;int b = 2;i = a>=b;j = a<=b;k = a==b;x = a > b;y = a < b;z = a != b;System.out.println("x=" + x);System.out.println("y=" + y);System.out.println("z=" + z);System.out.println("i=" + i);System.out.println("j=" + j);System.out.println("k=" + k);}}?
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实例7? 逻辑运算符
public class LSign {public static void main(String[] args) {boolean a, b,c, d, e ;a = 'a' > 'b';b = 'R' != 'r';c = !a;d = a && b;e = a || b;System.out.println("c=" + c);System.out.println("d=" + d);System.out.println("e=" + e);}}?
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实例8? 位运算符
public class ByteOperation {public static void main(String[] args) {int a = 32;int b = 12;int x = a & b;int y = a | b;int z = a ^ b;System.out.println("输出的结果是："+a + "&" + b + "=" + x);System.out.println("输出的结果是："+a + "|" + b + "=" + y);System.out.println("输出的结果是："+a + "^" + b + "=" + z);}}??
实例9? 移位运算符
public class Bit {public static void main(String[] args) {int a = 35;int b = 2;int c = a << b;int d = a >> b;int e = a >>> b;System.out.println(a + "<<" + b + "=" + c);System.out.println(a + ">>" + b + "=" + d);System.out.println(a + ">>>" + b + "=" + e);}}?
实例10? 转型运算符
public class Type {public static void main(String[] args) {int a;double b;a = (int) 46.5 + (int) 14.7;// 强制转型可能引起精度丢失b = (double) a;System.out.println("a=" + a);System.out.println("b=" + b);}}?
实例11? 常量与变量
class TestClass {final String string = "你好！";// 声明常量并赋值final double dou = 3.14;// 声明常量并赋值}public class Control_10 {int number = 0;// 定义int型变量numberpublic void print(Object obj) {// 创建print方法，其作用是将传入的Object型参数输出System.out.println("对象Object:" + obj);}public void print(TestClass tc) {// 创建print方法，其作用是将传入的TestClass型参数输出System.out.println("类TestClass:" + tc);}private void showObject() { // 显示实例化对象的信息TestClass tc = new TestClass(); // 将对象实例化System.out.println("TestClass.string= " + tc.string); // 输出TestClass对象的string属性值System.out.println("TestClass.dou= " + tc.dou);// 输出TestClass对象的fPi属性值}public static void main(String[] args) {Control_10 c10 = new Control_10(); // 创建Control_10类对象c10.number = 3; // 给number变量赋值System.out.println("number变量的值为： " + c10.number);c10.showObject(); // 调用方法showObject()c10.print(null); // 调用方法run()}}?
实例12? 各种进制的转换
import java.util.Scanner;public class TextZhuanhuan { // 定义一个进制转换的类public static int ZhuanToTen(int a, String str) {// 其它进制转成十进制double d = 0; // 声明转换后的数值String subString;// 根据字符串的长度循环获得单个元素for (int i = 0; i < str.length(); i++) {subString = str.substring(i, i + 1); // 将字符串按循环截取if (a == 16) { // 判断是否是十六进制subString = sixteenToNumber(subString); // 将字母转换成数字}d += Integer.parseInt(subString)// 返回转换的结果* Math.pow(a, str.length() - i - 1);}return (int) d;}public static String TenToNumber(int a, String str) {// 十进制转成其他进制int current = Integer.parseInt(str); // 将字符转换成整数String opResult = "";// 判断转换后的数制是否是16进制if (a == 16) {// 判断传入的数是否大于16，大于则逢16进一while (current >= a) {opResult += sixteenNumberToChar(current % a);// 将数字转换成字母current /= a;}if (current != 0)opResult += sixteenNumberToChar(current);} else {// 判断传入的值是否大于转换后的数制while (current >= a) {opResult += current % a;current /= a;}if (current != 0)opResult += current;}String riResult = ""; // 倒序二进制字符串// 根据二进制的转换方式进行循环输出for (int i = opResult.length() - 1; i >= 0; i--) {riResult = riResult + opResult.substring(i, i + 1);}return riResult;}public static String sixteenToNumber(String s) { // 十六进制字母对应数字String num = "";if (s.equals("A") || s.equals("a"))num = "10";else if (s.equals("B") || s.equals("b"))num = "11";else if (s.equals("C") || s.equals("c"))num = "12";else if (s.equals("D") || s.equals("d"))num = "13";else if (s.equals("E") || s.equals("e"))num = "14";else if (s.equals("F") || s.equals("f"))num = "15";elsenum = s;return num;}public static String sixteenNumberToChar(int num) { // 十六进制数字对应字母String c = "";if (num == 10)c = "A";else if (num == 11)c = "B";else if (num == 12)c = "C";else if (num == 13)c = "D";else if (num == 14)c = "E";else if (num == 15)c = "F";elsec = String.valueOf(num);return c;}public static void main(String[] args) { // java程序的主入口处String number; // 要转换的数int a, b;// a表示转换前的进制，b表示转换后的进制String result = "";// 经过数制转换后的结果String stop = "";Scanner read = new Scanner(System.in); // 得到用户输入的值do {System.out.println("输入三个整数：待转换的数据 要转换之前的进制 要转换后的进制");number = read.next();a = read.nextInt();b = read.nextInt();stop = "Quit";} while (stop != "Quit");try {if (a != 10) {// 判断转换前的数制是否是十进制String temp = String.valueOf(ZhuanToTen(a, number)); // 转换成十进制的数result = String.valueOf(TenToNumber(b, temp)); // 十进制转换成其它进制} else {result = String.valueOf(TenToNumber(b, number)); // 十进制转换成其它进制}System.out.println(a + "进制的数:" + number + ",转换成" + b + "进制的数为："+ result);} catch (Exception e) {System.out.print("转换失败，请正确输入！");System.exit(-1);}}}?
实例13? Java中的进制与移位运算符
public class Control_12 {public static void main(String[] args) {System.out.println("对Int型数据进行移位的例子如下：\n");Random rand = new Random(); // 实例化一个Random对象int a = rand.nextInt(); // 生成一个int型的随机数变量aint b = rand.nextInt(); // 生成一个int型的随机数变量b// 以下方法均调用IntleftMove方法IntleftMove("-1", -1);IntleftMove("+1", +1);int constant = 256987454;// 定义一个整型变量IntleftMove("Constant", constant);int negative = -256987454;// 定义一个整型变量IntleftMove("Negative", negative);IntleftMove("a", a);IntleftMove("~a", ~a);IntleftMove("-a", -a);IntleftMove("b", b);IntleftMove("a & b", b & b);IntleftMove("a b", a);IntleftMove("a ^ b", a ^ b);IntleftMove("a << 3", a << 3);IntleftMove("i >> 3", a >> 3);IntleftMove("(~a) >> 3", (~a) >> 3);IntleftMove("a >>> 3", a >>> 3);IntleftMove("(~a) >>> 3", (~a) >>> 3);System.out.println("\n对long型数据进行移位的例子如下：\n");long c = rand.nextLong();// 生成一个long型的随机数变量clong d = rand.nextLong();// 生成一个long型的随机数变量dLongleftMove("-1L", -1L);LongleftMove("+1L", +1L);long Lconstant = 8454564564684456954L;// 定义一个长整型变量LongleftMove("Lconstant", Lconstant);long Lnegative = -8454564564684456954L;// 定义一个长整型变量LongleftMove("Lnegative", Lnegative);// 以下方法均调用LongleftMove方法LongleftMove("c", c);LongleftMove("~c", ~c);LongleftMove("-c", -c);LongleftMove("d", d);LongleftMove("c & d", c & d);LongleftMove("c d", c | d);LongleftMove("c ^ d", c ^ d);LongleftMove("c << 3", c << 3);LongleftMove("c >> 3", c >> 3);LongleftMove("(~c) >> 3", (~c) >> 3);LongleftMove("c >>> 3", c >>> 3);LongleftMove("(~c)>>> 3", (-c) >>> 3);}static void IntleftMove(String s, int i) { // 定义一个静态方法，带两个参数System.out.println("int var="+s + "=" + i + ", 其二进制代码如下: ");for (int j = 31; j >= 0; j--)if (((1 << j) & i) != 0) {// 判断变量b左移一位与a变量做"与"操作，看是否不等于0System.out.print("1");//如果不等于0，则输出1} else {System.out.print("0");//否则输出0}System.out.println("");}static void LongleftMove(String s, long l) {// 定义一个静态方法，方法中带两个参数System.out.println("long var= "+s+"=" + l + ", 其二进制代码如下: ");for (int i = 63; i >= 0; i--) {if (((1L << i) & l) != 0) {System.out.print("1");} else {System.out.print("0");}}System.out.println("");}}?