String s = new String（"xyz");创建了几个String Object？二者之间有什么区别？

下面程序执行后，屏幕上显示的应是______。 public class Testl0 { public static void main(String[] args) { char char1[] = {'t', 'e', 's', 't'}; char char2[] = ('t', 'e', 's', 't', '1 }; String s1 = new String(char1); String s2 = new String(char2, 0, 4); System.out.println (si.equal (s2)); } }

A．true

B．假

C．test

D．编译错误

下列代码段的执行结果是()。 public class Test { public static void main(String args[ ]) { String s1= new String("hello"); String s2= new String("hello"); System.out.println(s1==s2); System.out.println(s1.equal(s2)); } }

A．true false

B．true true

C．false true

D．false false

下列程序段的输出是()。 public class Test { public static void main (String args[ ]) { String ss1 = new String("hello"); String ss2 = new String("hello"); System. out. println(ssl == ss2); System. out. println (ss1. equals(ss2)); } }

A．true, false

B．true, true

C．false, true

D．false, false

程序阅读：class Myexception extends Exception

{

Myexception ()

{

super();

}

Myexception(String msg)

{

super(msg);

}

}

public class Test

{

public static void main(String args[])

{

try

{

throw new Myexception(“自定义异常”);

}

catch(Myexception e)

{

System.out.println(e.getMessage());

}

}

}

请完成下列Java程序：读取自己的源文件并把它压缩成GZIP文件。

注意：请勿改动main()主方法和其他已有语句内容，仅在下划线处填入适当的语句。

import java.io.*;

import java.util.zip.*;

public class exl6 2 {

public static void main{String[] arg) {

ex16_2 obj16_2 = new ex16_2();

obj16_2.doZip("ex16_2.java","ex16_2.gzip")

}

public void doZip(String strIn,String strOut

FileInputStream in;

FileOutputStream out;

GZIPOutputStream gzip;

int nFileLength;

byte[] barray = new byte[10];

try {

in = new FileInputStream(strIn);

out = new FileOutputStream(strOut);

gzip = new GZIPOutputStream(out);

while((nFileLength = in.read(barray, 0 barray.length)) ＞ 0)

_____________________;

______________________;

gzip.close();

} catch(Exception e) {

e.printStackTrace();

}

}

}

给出下面的代码：

public class Person{

static int arr[] =new int[10];

public static void main(String a[]) {

System.out.println(arr[1];)

}

}

以下叙述对的是______。

A．编译时将发生错误 B．编译时正确但是运行时出错

C．输出为0 D．输出为null

串（有双引号界定符）。单击窗体，打开Alph.txt文件，读取字符串显示在文本框Text1中，最后将重新排列的字符串存入AipO.txt文件中（无双引号界定符）。请选择横线处合适的语句 Private Sub Fom_Load() Dim StrIn As String,StrOut As String Open"C/:Alph.txt"For Input As#1 ______ Close Text1.Text=StrIn ______ Text2.Text=StrOut Open"C/:AlpO.txt"For Output As#2 ______ Close End Sub Private Function StrSort(s As String)As String Dim sArr()As String*1,i As Integer,j As Integer,n As Integer Dim t As String*1 n=Lem(s) Redim sArr(n) For i=1 To n sArr(i)=Mid(s,i,1) Next i For i=1 To n-1 For j=i+1 To n If sArr(i)＞sArr(j)Then t=sArr(i):sArr(i)=sArr(j):sArr(j)=t End If Next j,i For i=1 To n StrSort=StrSort&sArr(i) Next i End FunctionA.Input#1,StrIn StrIn Print#2,StrOut B.Input#1,StrIn StrOut(StrIn) Print#2,StrOutC.Input#2,StrIn StrOut(StrIn) Print#1,StrOutD.Input#1,StrIn StrOut(StrIn) Input#2,StrOut

在C盘当前文件夹下有一个已建立好的顺序文件Alph.txt，文件内容为只含有字母的一个字符串(有双引号界定符)。单击窗体，打开Alph.txt文件，读取字符串并显示在文本框Text1中，然后调用StrSort过程将此字符串按ASCII码的顺序重新排列并显示在文本框Text2，最后将重新排列的字符串存入AlpO.txt文件中(无双引号界定符)。请选择横线处合适的语句 ()。 Private Sub Form_Load()Dim StrIn As String, StrOut As String Open "C:\ Alph.txt" For Input As #1 ______ Close Text1.Text=StrIn ______ Text2.Text=StrOut Open "C:\ AlpO.txt" For Output As #2 ______ CloseEnd SubPrivate Function StrSort(s As String) As String Dim sArr() As String *1, i As Integer, j As Integer, n As Integer Dim t As String*1 n=Len(s) ReDim sArr(n) For i= 1 To n sArr(i) = Mid(s, i, 1) Next i For i=1 To n-1 For j=i+1 To n If sArr(i) ＞ sArr(j) Then t=sArr(i): sArr(i)=sArr(j):sArr(j)=t End If Next j, i For i=1 To n StrSort = StrSort & sArr(i) Next i End Function

A．Input #1, StrIn StrIn Print #2, StrOut

B．Input #1, StrIn StrSort(StrIn) Print #2, StrOut

C．Input #2, StrIn StrSort(StrIn) Print #1, StrOut

D．Print #1, StrIn StrSort(StrIn) Input #2, StrOut

下列程序的输出结果是()。 public class Test { public static void main (String[] args) { String s="hello"； s.replace ('r','m')； System.out.println(s)； } }

A．hello

B．HELLO

C．hemmo

D．HEMMO

下面程序执行后的输出结果为()。 public class fun { public static void main(String args[]) { String greets = " How are you!"; String s = greets.substring(0,3); System.out.println(s); } }

A．How

B．are

C．you

D．how are you!

在程序的下画线处应填入的选项是（）。 public class Test {： public static void main(String args[]){ Test t=new Test； Thread tt=new Thread(t)； tt．start； } public void run{ for(int i=0；i＜5；i++){ System．out．println("i="+i)； } } }

A.implements Runnable

B.extends Thread

C.implements Thread

D.extends Runnable