java编程思想第四版第十三章字符串 习题
- fas
- 第二题
package net.mindview.strings; import java.util.ArrayList;
import java.util.List; /**
* 无限循环
*/
public class InfiniteRecursion {
public InfiniteRecursion(){ }
@Override
public String toString() {
return " InfiniteRecursion address" + super.toString() + "\n";
}
public static void main(String[] args) {
List<InfiniteRecursion> list = new ArrayList<InfiniteRecursion>();
for(int i=; i<; i++){
list.add(new InfiniteRecursion());
}
System.out.println(list);
}
} - fa
- 第四题
package net.mindview.strings; import java.util.Formatter; public class Receipt {
private double total = ;
private Formatter f = new Formatter(System.out);
public final int ITEM_WIDTH = ;
public final int QTY_WIDTH = ;
public final int PRICE_WIDTH = ;
public final int PRICISION_FLOAT_WIDHT = ;
public final int PRICISION_String_WIDHT = ;
public final String TITLE_FORMAT = "%-" + ITEM_WIDTH + "s %" + QTY_WIDTH
+ "s %" + PRICE_WIDTH + "s\n";
public final String PRICE_FORMAT = "%-" + ITEM_WIDTH + "."
+ PRICISION_String_WIDHT + "s %" + QTY_WIDTH + "d %" + PRICE_WIDTH
+ "." + PRICISION_FLOAT_WIDHT + "f\n";
public final String TOTAL_FORMAT = "%-" + ITEM_WIDTH + "s %" + QTY_WIDTH
+ "s %" + PRICE_WIDTH + "." + PRICISION_FLOAT_WIDHT + "f\n"; //打印标题
public void printTitle(){
/*
* 含义: 格式化字符串串以%开头
* -: 表示左对齐
* 15: 15表示宽度
* s:表示数据的类型是String
* .2f:表示浮点数保留的小数位数
* .15s:表示字符串的长度最多15个字符
*/
f.format(TITLE_FORMAT, "Item", "Qty", "Price");
f.format(TITLE_FORMAT, "----", "---", "-----");
} //正文的内容
public void print(String name, int qty, double price){
f.format(PRICE_FORMAT, name, qty, price);
total += price;
} //总价
public void printTotal(){
f.format(TOTAL_FORMAT, "Tax", "", total*0.06);
f.format(TITLE_FORMAT, "", "", "-----");
f.format(TOTAL_FORMAT, "Total", "", total*1.06);
} public static void main(String[] args) {
Receipt receipt = new Receipt();
receipt.printTitle();
receipt.print("Jack`s Magic Beans", , 4.25);
receipt.print("Princess Peas", , 5.1);
receipt.print("Three Bears Porridge", , 14.29);
receipt.printTotal();
} }运行结果：
Item Qty Price
---- --- -----
Jack`s Magic Be 4.25
Princess Peas 5.10
Three Bears Por 14.29
Tax 1.42
-----
Total 25.06 - 第五题
package net.mindview.strings; import java.util.Formatter; public class Receipt {
private double total = ;
private Formatter f = new Formatter(System.out);
public final int ITEM_WIDTH = ;
public final int QTY_WIDTH = ;
public final int PRICE_WIDTH = ;
public final int PRICISION_FLOAT_WIDHT = ;
public final int PRICISION_String_WIDHT = ;
public final String TITLE_FORMAT = "%-" + ITEM_WIDTH + "s %" + QTY_WIDTH
+ "s %" + PRICE_WIDTH + "s\n";
public final String PRICE_FORMAT = "%-" + ITEM_WIDTH + "."
+ PRICISION_String_WIDHT + "s %" + QTY_WIDTH + "d %" + PRICE_WIDTH
+ "." + PRICISION_FLOAT_WIDHT + "f\n";
public final String TOTAL_FORMAT = "%-" + ITEM_WIDTH + "s %" + QTY_WIDTH
+ "s %" + PRICE_WIDTH + "." + PRICISION_FLOAT_WIDHT + "f\n"; //打印标题
public void printTitle(){
/*
* 含义: 格式化字符串串以%开头
* -: 表示左对齐
* 15: 15表示宽度
* s:表示数据的类型是String
* .2f:表示浮点数保留的小数位数
* .15s:表示字符串的长度最多15个字符
*/
f.format(TITLE_FORMAT, "Item", "Qty", "Price");
f.format(TITLE_FORMAT, "----", "---", "-----");
} //正文的内容
public void print(String name, int qty, double price){
f.format(PRICE_FORMAT, name, qty, price);
total += price;
} //总价
public void printTotal(){
f.format(TOTAL_FORMAT, "Tax", "", total*0.06);
f.format(TITLE_FORMAT, "", "", "-----");
f.format(TOTAL_FORMAT, "Total", "", total*1.06);
} public static void main(String[] args) {
Receipt receipt = new Receipt();
receipt.printTitle();
receipt.print("Jack`s Magic Beans", , 4.25);
receipt.print("Princess Peas", , 5.1);
receipt.print("Three Bears Porridge", , 14.29);
receipt.printTotal();
} }运行结果:
Item Qty Price
---- --- -----
Jack`s Magic Be 4.25
Princess Peas 5.10
Three Bears Por 14.29
Tax 1.42
-----
Total 25.06 - afd
- 第七题:
package net.mindview.strings.test7; public class Test7 { public static void main(String[] args) {
//两种写法都可以
String regex = "^[A-Z].*\\.$";
String regex1 = "\\p{Upper}.*\\.$";
String str = "D.";
String str1 = "Dfasdfasfasfdasfdasfasfasdf.";
String str2 = "Dfasdfasfasfdasfdasfasfasdf.E";
System.out.println(str.matches(regex));
System.out.println(str1.matches(regex));
System.out.println(str2.matches(regex));
System.out.println(str.matches(regex1));
System.out.println(str1.matches(regex1));
System.out.println(str2.matches(regex1));
}
}运行结果:
true
true
false
true
true
false - 第八题
package net.mindview.strings; import java.util.Arrays; public class Splitting { public static String knights = "Then, when you have found the shrubbery, you must cut down the mightiest tree in the forest... with... a herring!"; public static void split(String regex){
System.out.println(Arrays.toString(knights.split(regex)));
}
public static void main(String[] args) {
//表示的时按照空格分割字符串
//运行结果:[Then,, when, you, have, found, the, shrubbery,, you, must, cut, down, the, mightiest, tree, in, the, forest..., with..., a, herring!]
split(" "); //表示按照非单次字符分割字符串--这里的非单次字符是空格和,
//运行结果:[Then, when, you, have, found, the, shrubbery, you, must, cut, down, the, mightiest, tree, in, the, forest, with, a, herring]
split("\\W+");
//这个表示:费单次字符之前带n的地方进行分割字符串 这里的分割符是n空格和n,
//运行结果:[The, whe, you have found the shrubbery, you must cut dow, the mightiest tree i, the forest... with... a herring!]
split("n\\W+");
} }package net.mindview.strings.test8; import net.mindview.strings.Splitting; public class Test8 { public static void main(String[] args) {
String regex = "the|you";
Splitting.split(regex);
}
} - 第九题
package net.mindview.strings.test9; import net.mindview.strings.Splitting; public class Test9 {
public static void main(String[] args) {
String regex = "A|E|I|O|U|a|e|i|o|u";
//通过嵌入式标志表达式 (?i) 也可以启用不区分大小写的匹配。
String regex1 = "(?i)a|e|i|o|u";
//[abc] 表示a或b或c
String regex2 = "(?i)[aeiou]";
System.out.println(Splitting.knights.replaceAll(regex, "_"));
System.out.println(Splitting.knights.replaceAll(regex1, "_"));
System.out.println(Splitting.knights.replaceAll(regex2, "_"));
}
} - 第十题
package net.mindview.strings.test10; import java.util.regex.Matcher;
import java.util.regex.Pattern; public class Test10 {
public static void main(String[] args) {
String str = "Java now has regular expressions"; for(String arg: args){
Pattern p = Pattern.compile(arg);
Matcher m = p.matcher(str);
while(m.find()){
System.out.println("Match \"" + m.group() +"\" at positions " + m.start() + "-" + (m.end()-) );
}
System.out.println("\n");
} }
}输入参数:
^Java
\Breg.*
n.w\s+h(a|i)s
s?
s*
s+
s{}
s{}.
s{,}输出结果
Match "Java" at positions - Match "now has" at positions - Match "" at positions --
Match "" at positions -
Match "" at positions -
Match "" at positions -
Match "" at positions -
Match "" at positions -
Match "" at positions -
Match "" at positions -
Match "" at positions -
Match "" at positions -
Match "" at positions -
Match "s" at positions -
Match "" at positions -
Match "" at positions -
Match "" at positions -
Match "" at positions -
Match "" at positions -
Match "" at positions -
Match "" at positions -
Match "" at positions -
Match "" at positions -
Match "" at positions -
Match "" at positions -
Match "" at positions -
Match "" at positions -
Match "" at positions -
Match "s" at positions -
Match "s" at positions -
Match "" at positions -
Match "" at positions -
Match "" at positions -
Match "s" at positions -
Match "" at positions - Match "s" at positions -
Match "ss" at positions -
Match "s" at positions - Match "s " at positions -
Match "ss" at positions - Match "" at positions --
Match "" at positions -
Match "" at positions -
Match "" at positions -
Match "" at positions -
Match "" at positions -
Match "" at positions -
Match "" at positions -
Match "" at positions -
Match "" at positions -
Match "" at positions -
Match "s" at positions -
Match "" at positions -
Match "" at positions -
Match "" at positions -
Match "" at positions -
Match "" at positions -
Match "" at positions -
Match "" at positions -
Match "" at positions -
Match "" at positions -
Match "" at positions -
Match "" at positions -
Match "" at positions -
Match "" at positions -
Match "" at positions -
Match "ss" at positions -
Match "" at positions -
Match "" at positions -
Match "" at positions -
Match "s" at positions -
Match "" at positions - - 第十一题
package net.mindview.strings.test11; import java.util.regex.Matcher;
import java.util.regex.Pattern; public class Test11 {
public static void main(String[] args) {
Pattern p = Pattern.compile("(?i)((^[aeiou])|(\\s+[aeiou]))\\w+?[aeiou]\\b");
Matcher m = p.matcher("Arline ate eight apples and " +
"one orange while Anita hadn't any"); while(m.find()){
System.out.println("Match \"" + m.group() +
"\" at positions " + m.start() + "-" +
(m.end() - ));
}
}
}运行结果:
Match "Arline" at positions -
Match " ate" at positions -
Match " one" at positions -
Match " orange" at positions -
Match " Anita" at positions - - sfa
- f
- a
- fda
- sdf
- af
- a
- fd
- af
- as
- fd
- asfd
- af
- da
- f
- df
- as
- fa
- sf
- asf
- a
- sf
- af
- asf
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