J2se练习题目及答案VIP

1 Java初学者第一个小程序public class HelloWorld public static void main(String args) System.out.println(Hello World!);2 break练习public class TestBreak public static void main(String args) int stop = 4;for(int i=1; i=10; i+) if(i = stop) break; else System.out.println(i);3 continue练习public class TestContinute public static void main(String args) int con = 3;for(int i=1; i=5; i+) if(i = con) continue; else System.out.println(i);4 使用非递归的方法求Fibonacci数列第5个数是多少? /1, 1, 2, 3, 5, 8, 13public class TestFab public static void main(String args) System.out.println(method(5);public static long method(int index) if(index = 1 | index = 2) return 1;long f1 = 1L;long f2 = 1L;long f = 0;for(int i=0; iindex-2; i+) f = f1 + f2;f1 = f2;f2 = f;return f;5 使用递归求Fibonacci数列第5个数是多少?答:5public class TestFibonacci public static void main(String args) System.out.println(method(5);public static int method(int n) if(n = 1 | n = 2) return 1; else return method(n - 1) + method(n - 2);6 使用for循环求1! + 2! + 3! + . + 10! = 4037913;public class TestFor1 public static void main(String args) long f = 1L;long result = 0;for(int i=1; i=10; i+) f *= i;result += f;System.out.println(result);7 使用for循环求1 + 3 + 5 + . + 99 = 2500;public class TestFor2 public static void main(String args) int result = 0;for(int i=1; i=99; i+=2) result += i;System.out.println(result);8 if练习public class TestIF public static void main(String args) int i = 20;if(i20) System.out.println(i 20); else if (i40) System.out.println(i 60) System.out.println(asf); else System.out.println(kasjfla);9 使用递归求5! = 120;public class TestJC public static void main(String args) System.out.println(method(5);public static int method(int n) if(n = 1) return 1; else return n * method(n - 1);10 方法的调用举例public class TestMethod public static void main(String args) m1();m2(5);m3(4,5);System.out.println(m4(4, 6);public static void m1() /return;System.out.println(OK);public static void m2(int i) if(i3) return; else System.out.println(i);public static void m3(int i, int j) System.out.println(i + j);public static int m4(int i, int j) return i j ? i : j;11 switch问题举例，注意穿透现象public class TestSwitch public static void main(String args) int i = 3;switch(i) case 3 :System.out.println(A);break;case 5 :System.out.println(B);break;default:System.out.println(error); 12 while do while 举例，将1到9输出public class TestWhile public static void main(String args) int i = 1;while(i=9) System.out.print(i + );i+;System.out.println();i = 1;do System.out.print(i + );i+; while (i=9);13 求3维空间两点坐标之间的距离的平方class Point double x;double y;double z;Point(double x, double y, double z) this.x = x;this.y = y;this.z = z;void setX(double x) this.x = x;void setY(double y) this.y = y;void setZ(double z) this.z = z;double getDistance(Point p) return (x - p.x)*(x - p.x) + (y - p.y)*(y - p.y) + (z - p.z)*(z - p.z);public class TestPoint public static void main(String args) Point p1 = new Point(1.0, 2.0, 3.0);Point p2 = new Point(0.0, 0.0, 0.0);System.out.println(p1.getDistance(p2);p1.setY(1.0);System.out.println(p1.getDistance(new Point(1.0, 1.0, 3.0);14 重写equals方法判定两只猫是否相等public class TestEquals public static void main(String args) String s1 = a;String s2 = a;System.out.println(s1 = s2);System.out.println(s1.equals(s2);String s3 = new String(hello);String s4 = new String(hello);System.out.println(s3 = s4);System.out.println(s3.equals(s4);Cat c1 = new Cat(1, 2, 3);Cat c2 = new Cat(1, 2, 3);System.out.println(c1 = c2);System.out.println(c1.equals(c2); class Cat int color;int weight;int height;Cat(int color, int weight, int height) this.color = color;this.weight = weight;this.height = height;public boolean equals(Object obj) if(obj = null) return false; else if(obj instanceof Cat) Cat c = (Cat)obj;if(this.color = c.color & this.height = c.height & this.weight = c.weight) return true;return false;15 多态举例package com.dt;public class TestDt public static void main(String args) Cat c = new Cat(catname, yellow);Dog d = new Dog(dogname, black);Lady l1 = new Lady(l1, c);Lady l2 = new Lady(l2, d);l1.myPetEnjoy();l2.myPetEnjoy();class Animal private String name;Animal(String name) = name;public void enjoy() System.out.println(动物的叫声.);class Cat extends Animal private String eyeColor;Cat(String n, String eyeColor) super(n);this.eyeColor = eyeColor;public void enjoy() System.out.println(猫的叫声.);class Dog extends Animal private String furColor;Dog(String n, String furColor) super(n);this.furColor = furColor;public void enjoy() System.out.println(狗的叫声.);class Lady private String name;private Animal pet;Lady(String name, Animal pet) = name;this.pet = pet;public void myPetEnjoy() pet.enjoy();16 冒泡排序public class BubbleSort public static void main(String args) int a = new intargs.length;for(int i=0; iargs.length; i+) ai = Integer.parseInt(argsi);print(a);bubbleSort(a);print(a);private static void print(int a) for(int i=0; i=1; i-) for(int j=0; j aj+1) int temp = aj;aj = aj+1;aj+1 = temp;return a;17 使用数组数3退1:非面向对象的写法public class Count3Quit public static void main(String args) Boolean arr = new Boolean500;for(int i=0; i 1) if(arrindex = true) countNum +;if(countNum = 3) countNum = 0;arrindex = false;leftCount -;index +;if(index = arr.length) index = 0;for(int i=0; i 1) countNum +;if(countNum = 3) countNum = 0;kc.delete(k);k = k.right;class Kid int id;Kid(int id) this.id = id;Kid left;Kid right;class KidCircle int count = 0;Kid first, last;KidCircle(int n) for(int i=0; in; i+) add();void add() Kid k = new Kid(count);if(count = 0) first = k;last = k;k.left = k;k.right = k; else last.right = k;k.left = last;k.right = first;first.left = k;last = k;count +;void delete(Kid k) if(count = 0) return; else if(count = 1) first = last = null; else k.left.right = k.right;k.right.left = k.left;if(k = first) first = k.right; else if(k = last) last = k.left;count -;19 选择排序public class SelectionSort public static void main(String args) int a = new intargs.length;for(int i=0; iargs.length; i+) ai = Integer.parseInt(argsi);print(a);selectionSort(a);print(a);private static void print(int a) for(int i=0; ia.length; i+) System.out.print(ai + );System.out.println();private static void selectionSort(int a) int temp, k;for(int i=0; ia.length; i+) k = i;for(int j=k+1; j aj) k = j;if(k != i) temp = ai;ai = ak;ak = temp;20 简单运算器public class TestArgs public static void main(String args) double d1 = Double.parseDouble(args0);double d2 = Double.parseDouble(args2);double d = 0;if(args1.equals(+) d = d1 + d2; else if(args1.equals(-) d = d1 - d2; else if(args1.equals(x) d = d1 * d2; else if(args1.equals(/) d = d1 / d2; else System.out.println(error);System.out.println(d);21 数组拷贝练习public class TestArrayCopy public static void main(String args) int intArray = 1,2,3,4,5,6,7;int intArrayBak = new int3;System.arraycopy(intArray, 0, intArrayBak, 0, intArray.length);intArray21 = 100;for(int i=0; iintArray.length; i+) for(int j=0; jintArrayi.length; j+) System.out.print(intArrayij + );System.out.println(); 22 对日期排序public class TestDateSort public static void main(String args) Date days = new Date5;days0 = new Date(2006, 5, 4);days1 = new Date(2006, 7, 4);days2 = new Date(2008, 5, 4);days3 = new Date(2004, 5, 9);days4 = new Date(2004, 5, 4);Date d = new Date(2006, 7, 4);String str = String.valueOf(d);/str = d.toString();bubbleSort(days);for(int i=0; i=1;i-) for(int j = 0;j 0) Date temp = aj; aj=aj+1; aj+1=temp; return a; public static int binarySearch(Date days, Date d) if (days.length=0) return -1; int startPos = 0; int endPos = days.length-1; int m = (startPos + endPos) / 2; while(startPos 0) startPos = m + 1; if(pare(daysm) date.year ? 1 : year date.month ? 1 : month date.day ? 1 : day date.day ? -1 : 0; public String toString() return Year:Month:Day - + year + - + month + - + day; 23 二分法查找public class TestSearch public static void main(String args) int a = 1, 3, 6, 8, 9, 10, 12, 18, 20, 34 ;int i = 12;/System.out.println(search(a, i);System.out.println(binarySearch(a, i);public static int search(int a, int num) for(int i=0; ia.length; i+) if(ai = num) return i;return -1;public static int binarySearch(inta, int num) if (a.length=0) return -1; int startPos = 0; int endPos = a.length-1; int m = (startPos + endPos) / 2; while(startPos am) startPos = m + 1; if(num am) endPos = m -1; m = (startPos + endPos) / 2; return -1; 24 将字符串String s = 1,2;3,4,5;6,7,8;分解成一个double的二维数组public class ArrayParser public static void main(String args) double d;String s = 1,2;3,4,5;6,7,8;String sFirst = s.split(;);d = new doublesFirst.length;for(int i=0; isFirst.length; i+) /System.out.println(sFirsti);String sSecond = sFirsti.split(,);di = new doublesSecond.length;for(int j=0; jsSecond.length; j+) /System.out.println(sSecondj);dij = Double.parseDouble(sSecondj);for(int i=0; id.length; i+) for(int j=0; jdi.length; j+) System.out.println(dij);25 列出D:/A下边所以的文件及文件夹import java.io.*;public class FileList public static void main(String args) File f = new File(d:/A);System.out.println(f.getName();tree(f, 1);private static void tree(File f, int level) String str = ;for(int i=0; ilevel; i+) str += ;File childs = f.listFiles();for(int i=0; ichilds.length; i+) System.out.println(str + childsi.getName();if(childsi.isDirectory() tree(childsi, level + 1);26 枚举举例enum MyColor red3, green, blue;public class TestEnum public static void main(String args) MyColor m = MyColor.red3;long l1 = 3333333255252553L;int i = (int) l1;System.out.println(i);short s = 5; s = (short) (s + 2); s += 2; switch(m) case red3 :System.out.println(MyColor.red3);break;case green :System.out.println(B_green);break;case blue :System.out.println(C_blue);break;default :System.out.println(error);break;System.out.println(m.toString().intern()=red3);27 创建文件java.txtimport java.io.*;public class TestFile public static void main(String args) String seperator = File.separator;String fileName = naruto.txt;String directory = m1/m2;File f = new File(directory, fileName);if(f.exists() System.out.println(文件名是： + f.getAbsolutePath();System.out.println(文件大小是： + f.length(); else f.getParentFile().mkdirs();try f.createNewFile(); catch (IOException e) e.printStackTrace();public class TestString1 public static void main(String args) String s1 = hello;String s2 = world;String s3 = hello;System.out.println(s1 = s3); /trues1 = new String(hello);s2 = new String(hello);System.out.println(s1 = s2);System.out.println(s1.equals(s2);28 求下列String s = du*JG;中大写字母和小写字母，和其他个字符各多少个？public class TestString2 public static void main(String args) String s = du*JG;String lStr = abcdefghijklmnopqrstuvwxyz;String uStr = ABCDEFGHIJKLMNOPQRSTUVWXYZ;int lCount = 0;int uCount = 0;int oCount = 0;for(int i=0; is.length(); i+) char c = s.charAt(i);if(lStr.indexOf(c) != -1) lCount +; else if(uStr.indexOf(c) != -1) uCount +; else oCount +;System.out.print(lCount + + uCount + + oCount);29 求java这个字符串在下列字符串中出现的次数String s = 5454javaadsfjavaadfasfjavasdfajavaaadfjavaADFAjava545;public class TestString3 public static void main(String args) String s = 5454javaadsfjavaadfasfjavasdfajavaaadfjavaADFAjava545;int count = 0;while(s.indexOf(java) != -1) s = s.substring(s.indexOf(java) + java.length();count +;System.out.println(count);30 将文件复制到新的位置import java.io.*;public class FileCopy public static void main(String args) int b = 0; FileReader in = null; FileWriter out = null; try in = new FileReader(d:/share/java/HelloWorld.java); out = new FileWriter(d:/share/java/io/HW.java); while(b=in.read()!=-1) out.write(b); out.close(); in.close(); catch (FileNotFoundException e2) System.out.println(找不到指定文件); System.exit(-1); catch (IOException e1) System.out.println(文件复制错误); System.exit(-1); System.out.println(文件已复制); 31 缓冲区字节流举例import java.io.*;public class TestBufferStream1 public static void main(String args) try FileInputStream fis = new FileInputStream(E:/EclipseCode_MyEclipse/Chapter8/src/TestBufferStream1.java); BufferedInputStream bis = new BufferedInputStream(fis); int c = 0; System.out.println(bis.read(); System.out.println(bis.read(); bis.mark(100); for(int i=0;i=10 & (c=bis.read()!=-1;i+) System.out.print(char)c+ ); System.out.println(); bis.reset(); for(int i=0;i=10 & (c=bis.read()!=-1;i+) System.out.print(char)c+ ); bis.close(); catch (IOExce