摘要：
import java.awt.*; import javax.swing.*; public class JFrameDemo { public static void main(String[] args) { // TODO Auto-generated method stub JFrame 阅读全文
摘要：
public class ss { public static void main(String[] args) { String s1 = "ABCDEFG"; String s2 = new String ("ABCDEFG"); String s3 = s1.substring(0,4); S 阅读全文