public static void main (String[] args){
String[] fileNames = { "abc.txt", "bcd.exe",
"cde.exe","def.dat","efg.exe" };
for (String fileName : fileNames) {
if (fileName.endsWith(".exe")) {
System.out.print(fileName.substring(0,
stIndexOf(".exe"))+" ");
}
}
}
fileName.endsWith(".exe") 判断是否已".exe"结尾
substring(0,4) 截取0-3的字符串,不包含4 lastIndexOf(".exe") 获取".exe"最后一次出现的位置
答案:bcd cde efg
第二题:
public static void go(Long n) {
System.out.println("Long");
}
public static void go(Short n) {
System.out.println("Short");
}
public static void go(int n) {
System.out.println("int");
}
public static void main(String[] args) {
short y = 6;
long z = 7;
go(y);
go(z);
}
虽然y是short型的，但是编译器把它转换为int型
答案:int Long
public static void main(String[] args){
String test = "Test A. Test B. Test C.";
String regex = "\\.\\s*";
String[] result = test.split(regex);
for(String s : result)
System.out.print(s + " ");
}
\s 空白字符 *表示0个或任意多个 text.split("\\.")按.拆分答案: Test A Test B Test C
第四题:
public class AA{
private Long userId;
private String nickName;
public Long getUserId() {
return userId;
}
public void setUserId(Long userId) {
erId = userId;
}
public String getNickName() {
return nickName;
}
public void setNickName(String nickName) {
this.nickName = nickName;
}
public static void main(String[] args){
AA m1=new AA();
m1.setUserId(new Long(100001));
m1.setNickName("mick");
AA m2=new AA();
m2.setUserId(new Long(100001));
m2.setNickName("mick");
System.out.println(m1==m2);
System.out.println(m1.equals(m2));
}
equals方法返回值也是return m1==m2
答案:false false
运行下列代码，输出为false的是：（）。
A.String st1 = "abc";System.out.println("abc" == st1);
B.Stringst2=
"abc"System.out.println(st2.equals(newString("abc")));
C.Integer i = 100; System.out.println(100 == i);
D.ArrayList list = new ArrayList();
System.out.println(list.contains(null));
答案：D
第六题
public interface Cookie{
Cookie cookie=new Cart ("小面包","盼盼");
}
public class Cart implements Cookie{
private String name;
private String production;
public Cart(String name,String production){
=name;
this.production=production;
}
public void smell(){
cookie =new Cart("蛋黄派","达利园");
}
}
final 要求属性不可更改cookie =new Cart("蛋黄派","达利园"); 这个修改了cookie的地址，所以报错
第七题
(多选)请看下列代码：
public abstract class Shape {
int x;
int y;
public abstract void draw();
public void setAnchor(int x, int y) {
this.x = x; this.y = y;
}
}
下列选项中能正确使用Shape类的是：
A.public class Circle implements Shape { private int radius; }
B.public abstract class Circle extends Shape { private int radius; }
C.public class Circle extends Shape { private int radius; public void
draw(); }
D.public class Circle extends Shape {
