java从入门到精通习题

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1、5.3publicclassEval{//新建类publicstaticvoidmain(String[]args){//主方法Stringregex="1[35]\d{9}";Stringtext="15000000000";if(text.matches(regex)){System.out.println(text+"是合法的手机号");}}}5.4publicclassEval{//新建类publicstaticvoidmain(String[]args){//主方法StringBuilderbuilder=newStringBuilder("a");fo

2、r(inti=1;i<=10;i++){builder.append(i);}System.out.println(builder.toString());}}6.1importjava.util.*;publicclassEval{//创建类publicstaticvoidmain(String[]args){intarr1[]=newint[]{1,2,3,4,5};intarr2[]=Arrays.copyOf(arr1,3);//复制源数组中从下标0开始的3个元素到目的数组，从下标0的位置开始存储。for(inti=0;i

3、ystem.out.print(arr1[i]);System.out.println();for(intj=0;j

4、.3importjava.util.*;publicclassText{//创建类publicstaticvoidmain(String[]args){Stringarr[]=newString[]{"ac","bc","dc","yc"};System.out.println("替换前：");for(Stringstr:arr){System.out.print(str+"t");}Arrays.fill(arr,2,3,"bb");System.out.println("替换后：");for(Stringstr2:arr){System.out.print

5、(str2+"t");}}}6.4publicclassEval{//创建类publicstaticvoidmain(String[]args){intarr[][]=newint[][]{{1,2,3},{4,5,6},{7,8,9}};System.out.println("数组原有内容：");for(inti=0;i

6、组内容：");for(inti=0;i

7、cclassUseCase2extendsUseCase1{publicstaticvoidmain(String[]args){UseCase1u=newUseCase1();u.setName("123");System.out.println(u.getName());}}7.2packagecom.lzw;publicclassUseCase3{privatefloatheight;privatefloatwidth;publicUseCase3(floatheight,floatwidth){this.height=height;this.width=