Java作业@笔试题@2017.11.04-11.05

1:需求：请设计一个方法，可以实现获取任意范围内的随机数。

package org.wests.InterviewQuestion;/** * 1:需求：请设计一个方法，可以实现获取任意范围内的随机数。 * @author 代虎 * */public class Question01 {    public static void getRandom(double start,double end) {        double random =  Math.random()*(end-start)+start;        System.out.println(random);    }    public static void main(String[] args) {        getRandom(10, 20);        getRandom(0, 20);        getRandom(100, 200);    }}

执行结果：
15.760649486959991
12.00285416285148
145.76020942009

2:下面代码执行的结果是:public static void main(String[] args) {        String s1 = new String("hello");        String s2 = new String("hello");        System.out.print(s1 == s2);        System.out.print(",");        System.out.println(s1.equals(s2));    }}

执行结果：false,true

3:下面代码执行的结果是:

public static void main(String arg[]) {        StringBuffer a = new StringBuffer("A");        StringBuffer b = new StringBuffer("B");        operate(a, b);        System.out.println(a + "," + b);    }    static void operate(StringBuffer x, StringBuffer y) {        x.append(y);        y = x;    }

执行结果：AB,B

4、下列代码的执行结果是：

String str1 = "This is a test!";    StringBuffer str2 =new StringBuffer( "This is a test!");    str1 = str1+"Hi";    str2.append("Hi");    System.out.println("str1 == " + str1);    System.out.println("str2 == " + str2);

执行结果：str1 == This is a test ! Hi
str2 == This is a test ! Hi

以下为反编译的结果：

// Decompiled by Jad v1.5.8e2. Copyright 2001 Pavel Kouznetsov.// Jad home page: http://kpdus.tripod.com/jad.html// Decompiler options: packimports(3) fieldsfirst ansi space // Source File Name:   Question04.javapackage org.wests.InterviewQuestion;import java.io.PrintStream;public class Question04{    public Question04()    {    }    public static void main(String args[])    {        String str1 = "This is a test!";        StringBuffer str2 = new StringBuffer("This is a test!");        str1 = (new StringBuilder(String.valueOf(str1))).append("Hi").toString();        str2.append("Hi");        System.out.println((new StringBuilder("str1 == ")).append(str1).toString());        System.out.println((new StringBuilder("str2 == ")).append(str2).toString());    }}

5:下面代码能最后打印的值是?

public class TestValue {    private static int a;    public static void main(String[] args) {        modify(a);        System.out.println(a);    }    public static void modify(int a) {        a++;    }

执行结果： 0