习题1
源代码：
publicstatic void main(String[] args) {
int[]x= new int[20];
doublesum=0;
for(int i = 0; i < x.length; i++) {
x[i]=100+(int)(Math.random()*900);
sum+=x[i];
System.out.print(x[i]+" ");
if((i+1)%5==0) {
System.out.println();
}
}
System.out.println("该数组的平均数为："+(sum/20));
}
}
运行图
习题2
源代码：
publicstatic void main(String[] args) {
Strings1 = new String("you are a student");
Strings2 = new String("how are you");
if(s1.equals(s2)) { //使用equals方法判断s1与s2是否相同
System.out.println("s1与s2相同。");
}else{
System.out.println("s1与s2不同");
}
Strings3 = new String("2203021985");
if(s3.startsWith("220302")) {//判断s3的前缀是否是“220302”
System.out.println("吉林省的身份证。");
}
Strings4= new String("你");
Strings5= new String("我");
if(s4.compareTo(s5)>0) {//按着字典序s4大于s5的表达式
System.out.println("按字典序s4大于s5.");
}else{
System.out.println("按字典序s4小于s5.");
}
intposition= 0;
Stringpath= "c:\\java\\jsp\\A.java";
position=path.lastIndexOf("\\"); //获取path变量中最后出现目录分割符号的位置
System.out.println("c:\\\\java\\\\jsp\\\\A.java中最后出现\\的位置是："+position);
StringfileName= path.substring(12); //获取path中“A.java”字符串
System.out.println("c:\\java\\jsp\\A.java含有的文件名是："+fileName);
Strings6 = new String ("100");
Strings7 = new String ("123.678");
intn1=Integer.valueOf(s6); //将s6转换成int型数据
doublen2 = Double.valueOf(s7); //将s7转换成double型数据
doublem = n1+n2;
System.out.println(m);
Strings8 =String.valueOf(m); //String调用valueOf(int m)方法将m转换为字符串对象
position=s8.indexOf(".");
Stringtemp= s8.substring(position+1);
System.out.println("数字"+m+"有"+temp.length()+"位小数");
Strings9 = new String ("ABCDEF");
chara[]=s9.toCharArray(); //将s9存放到数组a中
for(int i = a.length-1;i>=0;i--) {
System.out.print(""+a[i]);
}
}
}
运行图
