0假设 s1是"Weicome"而 s2 是"welcome

1.

import java.util.Scanner;

import java.lang.*;

public class Stringhw {

public static void main(String[] args) {

String s1 = "Welcome";

String s2 = "welcome";

boolean isEqual = s1.equals(s2);

System.out.println(isEqual);

}

}

运行结果：false;

2.

import java.util.Scanner;

import java.lang.*;

public class Stringhw {

public static void main(String[] args) {

String s1 = "Welcome";

String s2 = "welcome";

boolean isEqual = s1.equalsIgnoreCase(s2);

System.out.println(isEqual);

}

}

运行结果：true

3.

import java.util.Scanner;

import java.lang.*;

public class Stringhw {

public static void main(String[] args) {

String s1 = "Welcome";

String s2 = "welcome";

int x = s1.compareTo(s2);

System.out.println(x);

}

}

运行结果：-32

4.

import java.util.Scanner;

import java.lang.*;

public class Stringhw {

public static void main(String[] args) {

String s1 = "Welcome";

String s2 = "welcome";

int x = s1.compareToIgnoreCase(s2);

System.out.println(x);

}

}

运行结果：0

5.

import java.util.Scanner;

import java.lang.*;

public class Stringhw {

public static void main(String[] args) {

String s1 = "Welcome";

String s2 = "welcome";

String s3 = "AAA";

boolean b = s1.startsWith(s3);

System.out.println(b);

}

}

运行结果：false

6.

import java.util.Scanner;

import java.lang.*;

public class Stringhw {

public static void main(String[] args) {

String s1 = "Welcome";

String s2 = "welcome";

String s3 = "AAA";

boolean b = s1.endsWith(s3);

System.out.println(b);

}

}

运行结果：false

7.

import java.util.Scanner;

import java.lang.*;

public class Stringhw {

public static void main(String[] args) {

String s1 = "Welcome";

String s2 = "welcome";

String s3 = "AAA";

int x = s1.length();

System.out.println(x);

}

}

运行结果：7

8.

import java.util.Scanner;

import java.lang.*;

public class Stringhw {

public static void main(String[] args) {

String s1 = "Welcome";

String s2 = "welcome";

String s3 = "AAA";

char x =s1.charAt(0);

System.out.println(x);

}

}

运行结果：W

9.

import java.util.Scanner;

import java.lang.*;

public class Stringhw {

public static void main(String[] args) {

String s1 = "Welcome";

String s2 = "welcome";

String s3 = s1.concat(s2);

System.out.println(s3);

}

}

运行结果：Welcomewelcome

10.

import java.util.Scanner;

import java.lang.*;

public class Stringhw {

public static void main(String[] args) {

String s1 = "Welcome";

String s2 = "welcome";

s1 = s1.substring(1);

System.out.println(s1);

}

}

运行结果：elcome

11.

import java.util.Scanner;

import java.lang.*;

public class Stringhw {

public static void main(String[] args) {

String s1 = "Welcome";

String s2 = "welcome";

s1 = s1.substring(1, 5);

System.out.println(s1);

}

}

运行结果：elco

12.

import java.util.Scanner;

import java.lang.*;

public class Stringhw {

public static void main(String[] args) {

String s1 = "Welcome";

String s2 = "welcome";

String s3 = s1.toLowerCase();

System.out.println(s3);

}

}

运行结果：welcome

13.

import java.util.Scanner;

import java.lang.*;

public class Stringhw {

public static void main(String[] args) {

String s1 = "Welcome";

String s2 = "welcome";

String s3 = s1.trim();

System.out.println(s3);

}

}

运行结果：Welcome

14.

import java.util.Scanner;

import java.lang.*;

public class Stringhw {

public static void main(String[] args) {

String s1 = "Welcome";

String s2 = "welcome";

int x = s1.indexOf('e');

System.out.println(x);

}

}

运行结果：1

15.

import java.util.Scanner;

import java.lang.*;

public class Stringhw {

public static void main(String[] args) {

String s1 = "Welcome";

String s2 = "welcome";

int x = s1.indexOf("abc");

System.out.println(x);

}

}

运行结果：-1