Java2实用教程（第二版）程序代码——第五章 数组与字符串
1
例子1
2import java.applet.*; import java.awt.*;
3public class Example5_1 extends Applet
4
{ float a[];
5
public void init()
6
{ a=new float[5];
7 a[0]=23.9f;a[1]=34.9f;a[2]=45f;a[3]=56.98f;a[4]=100f;
8
}
9 public void paint(Graphics g)
10 {
11g.drawString("a[0]="+a[0]+"a[1]="+a[1]+"a[2]"+a[2]+"a[3]="+a[3]+"a[4]="+ a[4],12,12);
12 }
13
}
14
15//例子2
16import java.applet.*;import java.awt.*;
17public class Example5_2 extends Applet
18{ String tom;
19 public void init()
20 { tom="220302620629021";
21 }
22 public void paint(Graphics g)
23 { if((tom.startsWith("220302"))&&(tom.endsWith("1")||tom.endsWith("3")))
24 g.drawString("tom是吉林人,男性",10,10);
25 }
26}
27
28//例子3
29class Example5_3
30{ public static void main(String args[])
31 { int number=0;
32 String s="student;entropy;engage,english,client";
33 for(int k=0;k<s.length();k++)
34 { if(s.regionMatches(k,"en",0,2))
35 { number++;
36 }
37 }
38 System.out.println("number="+number);
39 }
40}
41
42//例子4
43class Example5_4
44{ public static void main(String args[])
45 { String a[]={"boy","apple","Applet","girl","Hat"};
46 for(int i=0;i<a.length-1;i++)
47 {for(int j=i+1;j<a.length;j++)
48 { if(a[j].compareTo(a[i])<0)
49 { String temp=a[i];
50 a[i]=a[j];
51 a[j]=temp;
52 }
53 }
54 }
55 for(int i=0;i<a.length;i++)
56 { System.out.print(" "+a[i]);
57 }
58 }
59}
60
61//例子5
62public class Example5_5
63{ public static void main(String args[])
64 { double n,sum=0.0 ;
65 for(int i=0;i<args.length;i++)
66 { sum=sum+Double.valueOf(args[i]).doubleValue();
67 }
68 n=sum/args.length;
69 System.out.println("平均数:"+n);
70 }
71}
72
73//例子6
74import java.util.Date;
75import java.awt.*;
76public class Example5_6
77{ public static void main(String args[])
78 { Date date=new Date();
79 Button button=new Button("确定");
80 System.out.println(date.toString());
81 System.out.println(button.toString());
82 }
83}
84
85//例子7
86import java.util.*;
87public class Example5_7
88{ public static void main(String args[])
89 { String s="I am Geng.X.y,she is my girlfriend";
90 StringTokenizer fenxi=new StringTokenizer(s," ,"); //空格和逗号做分
91 int number=fenxi.countTokens();
92 while(fenxi.hasMoreTokens())
93 { String str=fenxi.nextToken();
94 System.out.println(str);
95 System.out.println("还剩"+fenxi.countTokens()+"个单词");
96 }
97 System.out.println("s共有单词："+number+"个");
98 }
99}
100
101//例子8
102import java.util.*;
103public class Example5_8
104{ public static void main(String args[])
105 { String s=new String("abcABC123");
106 System.out.println(s);
107 char a[]=s.toCharArray();
108 for(int i=0;i<a.length;i++)
109 { if(Character.isLowerCase(a[i]))
110 { a[i]=Character.toUpperCase(a[i]);
111 }
112 else if(Character.isUpperCase(a[i]))
113 { a[i]=Character.toLowerCase(a[i]);
114 }
115 }
116 s=new String(a);
117 System.out.println(s);
118 }
119}
120
121//例子9
122class Example5_9
123{ public static void main(String args[])
124 { char c[],d[];
125 String s="巴西足球队击败德国足球队";
126 c=new char[2];
127 s.getChars(5,7,c,0);
128 System.out.println(c);
129 d=new char[s.length()];
130 s.getChars(7,12,d,0);
131 s.getChars(5,7,d,5);
132 s.getChars(0,5,d,7);
133 System.out.println(d);
134 }
135}
136
137//例子10
138class Example5_10
139{ public static void main(String args[])
140 { String s="清华大学出版社";
141 char a[]=s.toCharArray();
142 for(int i=0;i<a.length;i++)
143 { a[i]=(char)(a[i]^'t');
144 }
145 String secret=new String(a); System.out.println("密文:"+secret);
146 for(int i=0;i<a.length;i++)
147 { a[i]=(char)(a[i]^'t');
148 }
149 String code=new String(a); System.out.println("原文:"+code);
150 }
151}
152
153//例子11
154public class Example5_11
155{ public static void main(String args[])
156 { byte d[]="你我他".getBytes();
157 System.out.println("数组d的长度是(一个汉字占两个字节):"+d.length);
158 String s=new String(d,0,2);
159 System.out.println(s);
160 }
161}
162
例子12
import java.applet.*; import java.awt.*;3
public class Example5_1 extends Applet 4
{ float a[];
5
public void init() 6
{ a=new float[5];
7
a[0]=23.9f;a[1]=34.9f;a[2]=45f;a[3]=56.98f;a[4]=100f;8
}9
public void paint(Graphics g)10
{11
g.drawString("a[0]="+a[0]+"a[1]="+a[1]+"a[2]"+a[2]+"a[3]="+a[3]+"a[4]="+ a[4],12,12);12
}13
} 14
15
//例子216
import java.applet.*;import java.awt.*;17
public class Example5_2 extends Applet 18
{ String tom;19
public void init() 20
{ tom="220302620629021";21
}22
public void paint(Graphics g) 23
{ if((tom.startsWith("220302"))&&(tom.endsWith("1")||tom.endsWith("3")))24
g.drawString("tom是吉林人,男性",10,10);25
}26
}27
28
//例子329
class Example5_3 30
{ public static void main(String args[])31
{ int number=0; 32
String s="student;entropy;engage,english,client";33
for(int k=0;k<s.length();k++)34
{ if(s.regionMatches(k,"en",0,2))35
{ number++;36
}37
} 38
System.out.println("number="+number);39
}40
}41
42
//例子443
class Example5_4 44
{ public static void main(String args[]) 45
{ String a[]={"boy","apple","Applet","girl","Hat"};46
for(int i=0;i<a.length-1;i++) 47
{for(int j=i+1;j<a.length;j++) 48
{ if(a[j].compareTo(a[i])<0) 49
{ String temp=a[i];50
a[i]=a[j];51
a[j]=temp;52
}53
} 54
}55
for(int i=0;i<a.length;i++) 56
{ System.out.print(" "+a[i]);57
}58
}59
}60
61
//例子562
public class Example5_563
{ public static void main(String args[]) 64
{ double n,sum=0.0 ;65
for(int i=0;i<args.length;i++) 66
{ sum=sum+Double.valueOf(args[i]).doubleValue();67
}68
n=sum/args.length;69
System.out.println("平均数:"+n);70
}71
}72
73
//例子674
import java.util.Date;75
import java.awt.*;76
public class Example5_677
{ public static void main(String args[])78
{ Date date=new Date();79
Button button=new Button("确定");80
System.out.println(date.toString());81
System.out.println(button.toString()); 82
}83
}84
85
//例子786
import java.util.*;87
public class Example5_7 88
{ public static void main(String args[])89
{ String s="I am Geng.X.y,she is my girlfriend";90
StringTokenizer fenxi=new StringTokenizer(s," ,"); //空格和逗号做分91
int number=fenxi.countTokens();92
while(fenxi.hasMoreTokens()) 93
{ String str=fenxi.nextToken();94
System.out.println(str);95
System.out.println("还剩"+fenxi.countTokens()+"个单词");96
}97
System.out.println("s共有单词："+number+"个");98
} 99
}100
101
//例子8102
import java.util.*;103
public class Example5_8104
{ public static void main(String args[]) 105
{ String s=new String("abcABC123");106
System.out.println(s); 107
char a[]=s.toCharArray();108
for(int i=0;i<a.length;i++)109
{ if(Character.isLowerCase(a[i])) 110
{ a[i]=Character.toUpperCase(a[i]);111
}112
else if(Character.isUpperCase(a[i])) 113
{ a[i]=Character.toLowerCase(a[i]);114
}115
}116
s=new String(a);117
System.out.println(s); 118
} 119
}120
121
//例子9122
class Example5_9 123
{ public static void main(String args[])124
{ char c[],d[];125
String s="巴西足球队击败德国足球队";126
c=new char[2];127
s.getChars(5,7,c,0);128
System.out.println(c);129
d=new char[s.length()];130
s.getChars(7,12,d,0);131
s.getChars(5,7,d,5);132
s.getChars(0,5,d,7);133
System.out.println(d);134
}135
}136
137
//例子10138
class Example5_10 139
{ public static void main(String args[]) 140
{ String s="清华大学出版社";141
char a[]=s.toCharArray();142
for(int i=0;i<a.length;i++)143
{ a[i]=(char)(a[i]^'t');144
}145
String secret=new String(a); System.out.println("密文:"+secret);146
for(int i=0;i<a.length;i++)147
{ a[i]=(char)(a[i]^'t');148
}149
String code=new String(a); System.out.println("原文:"+code);150
}151
}152
153
//例子11154
public class Example5_11155
{ public static void main(String args[])156
{ byte d[]="你我他".getBytes(); 157
System.out.println("数组d的长度是(一个汉字占两个字节):"+d.length);158
String s=new String(d,0,2);159
System.out.println(s);160
}161
}162
