java基础学习（5）疯狂java讲义第4章课后习题解答源码

1.下面是疯狂java讲义习题后的源码，欢迎大家前来更新 、协作，一起把这本书后的习题做完，github开源地址：https://github.com/wei0long/javaLearn，现在只更新到第4章，后面陆续开始，欢迎大家前来push.

2.下面是1-5题源码：

t1.java

// created by dragon
public class t1 {
public static void main(String[] args){
for(int i=1;i<=9;i++){
for(int j=1;j<=i;j++){
System.out.print(i+"x"+j+"="+i*j);
if(2<=i && j!=i) System.out.print(",");
}

System.out.println();
}
}
}

t2.java

// created by dragon
import java.lang.Integer;
public class t2{
public static void main(String[] args){
int n = Integer.parseInt(args[0]);
for(int i=1;i<=n;i++){
for(int j=n-i;j>0;j--){
System.out.print(" ");
}
for(int k=1;k<=2*i-1;k++){
System.out.print("*");
}
System.out.println();

}
}
}

t3.java

// created by dragon
//注意 如果你是在windows命令行下，如果出现错误：编码的GBK的不可映射字符，请采用如下该编译
//javac -encoding utf-8 t3.java
import java.lang.Double;
public class t3{
public static void main(String[] args){
double r= Double.parseDouble(args[0]);//r是半径
for(double y=-r;y<=r;y+=2){//因为System.out.println看起来像隔行打印，所以步长为2
double a=Math.asin(y/r); //根据纵行坐标y算出角度(弧度)，因为y=r*sin(a)，所以sin(a)=y/x;
double x=r*Math.cos(a); //算出x坐标,不解释
for(double j=-r;j<=r;j++){//算出来的x坐标是正的，只能是半圆，打印整个圆从-r开始
System.out.print(Math.abs(j<0?j+x:j-x)<0.5?'*':' ');//double判断不能用==，用临近判断
}
System.out.println();
}
}
}

t4.java

import java.lang.Integer;
public class t4{
public static void main(String[] args){

// String s1 = "你是中国人";
String s1 = args[0];
int splitSplitLen = Integer.parseInt(args[1]);
splitString(s1,splitSplitLen);

}

public static void splitString(String src, int splitLen){
String splitStr;
if(null ==src){
System.out.println("No String input!");
} else {
// 源字符长度
// (关键点)将String转换成byte字节数组
byte bt[] = src.getBytes();
// System.out.println(bt.length);
//字符截半的话字节对于的ASC码是小于0的值

if(bt[splitLen]<0){
// 对于后截半的处理
splitLen=splitLen+1;
}
if(splitLen>bt.length){
// 切的字符长度不能大于字节长度
splitLen=bt.length;
}
// 重新构造一个新的截断字符串
splitStr = new String(bt,0,splitLen);
System.out.println("splitStr = "+ splitStr);

}
}
}

t5.java

import java.lang.Double;
public class t5{
public static void main(String[] args){

// double d1 = 123456789.233;
double d1 = Double.parseDouble(args[0]);
// System.out.println(number[0]);
// 将数字转换成人民大写数字
conventNum(d1);
}

public static void conventNum(double d1){
// 转为长整型
long numZ = (long)d1;
// System.out.println(numZ);
// 这里只考虑小数点后两位的情况
int numX =(int) Math.round((d1-numZ)*100);
// System.out.println(numX);
String numZs = numZ+"";
String str="";
// System.out.println(numZs);
// System.out.println(numZs.length());
switch(numZs.length()){
case 0:
str = IntNum(0,numZs,numX);
break;
case 1://个
str = IntNum(1,numZs,numX);
break;
case 2://十
str = IntNum(2,numZs,numX);
break;
case 3://百
str = IntNum(3,numZs,numX);
break;
case 4://千
str = IntNum(4,numZs,numX);
break;
case 5://万
str = IntNum(5,numZs,numX);
break;
case 6://十万
str = IntNum(6,numZs,numX);
break;
case 7://百万
str = IntNum(7,numZs,numX);
break;
case 8://千万
str = IntNum(8,numZs,numX);
break;
case 9://亿
str = IntNum(9,numZs,numX);
break;
default:
System.out.println("输入数据有误，请重新输入！");
break;
}
System.out.println(str);

}

public static String IntNum(int numZ,String numZs,int numX){
String[] number = new String[]{"零","壹","贰","叁","肆","伍","陆","柒","捌","玖"};
String[] danwei = new String[]{"元","拾","佰","仟","万","十万","佰万","仟万","亿"};
String[] xiaoshu = new String[]{"角","分"};
String ling="";
int lenNumzs =numZs.length();
String str="";
for(int i=0;i<numZ;i++){
// 将字符转化为整型
int num = (int)numZs.charAt(i)-48;
String s = number[num];
if(0==num){
str=str+s;
}else{
str=str+s+danwei[lenNumzs-1];
}
lenNumzs=lenNumzs-1;
}
// 小数部分转化
int n1 = numX/10;
int n0 = numX%10;
str=str+number[n1]+xiaoshu[0]+number[n0]+xiaoshu[1];
return str;
}
}

第6题原作者已经解答，这里不作重复工作.

第4章习题解答源码github下载