3.3学习内容：String类的多种方法

Q9-7：
package day22.t1;

public class TestQ9_7 {

public static void main(String[] args) {
	String s =new String("123456");
	int i = Integer.valueOf(s);
	System.out.println(i);
	
	Integer i1=Integer.valueOf(s);
	
	int i2 = i1;
	System.out.println(i2);

}

}
运行效果图：

8.ABC

11 / 12：
package day22.t1;

public class TestQ9_11 {

public static void main(String[] args) {
	String web ="[email protected]";
	
	System.out.println(web.substring(0, 7));
	
	int i = web.indexOf("@");
	int i1=web.indexOf(".");
	if(i!=-1 && i1!=-1){
		if(i

}
效果图：

13.
package day22.t1;

public class TestQ9_13 {

public static void main(String[] args) {
	String s =java.util.UUID.randomUUID().toString();
	
	System.out.println(s);
	
	String s1=s.replace('-', ' ');
	
	System.out.println(s1);

}

}

效果图：

package day22.t1;

public class TestQ9_14 {

public static void main(String[] args) {
	String s="ABCDEFGhigklmn1234567";
	
	java.util.Random random=new java.util.Random();
	
	StringBuilder sb= new StringBuilder();
	
	for(int i =1; i<=4;i++){
		int a =random.nextInt(21);
		char ch = s.charAt(a);
		sb.append(ch);
	}
	System.out.println(sb.toString());
	
	
}

}
效果图：

15

package day22.t1;

public class TestQ9_15 {

public static void main(String[] args) {
	String s ="1239586838923173478943890234092";
	
	String[] s1 =s.split("1");
	System.out.println("1出现了"+(s1.length-1)+"次");
	
	String[] s2 =s.split("2");
	System.out.println("2出现了"+(s2.length-1)+"次");
	
	String[] s3 =s.split("3");
	System.out.println("3出现了"+(s3.length-1)+"次");
	
	String[] s4 =s.split("4");
	System.out.println("4出现了"+(s4.length-1)+"次");
	
	String[] s5 =s.split("5");
	System.out.println("5出现了"+(s5.length-1)+"次");
	
	String[] s6 =s.split("6");
	System.out.println("6出现了"+(s6.length-1)+"次");
	
	String[] s7 =s.split("7");
	System.out.println("7出现了"+(s7.length-1)+"次");
	
	String[] s8 =s.split("8");
	System.out.println("8出现了"+(s8.length-1)+"次");
	
	String[] s9 =s.split("9");
	System.out.println("9出现了"+(s9.length-1)+"次");

}

}