• [Java] 常用类-01 String / StringBuffer


    package com.bjsxt.chap6;
    /**
     * @author hp
     *
     */
    public class Test {
        public static void main(String[] args) {
            String s1 = "hello";
            String s2 = "world!";
            String s3 = "hello";
            System.out.println(s1 == s3);
            
            s1 = new String("hello");
            s2 = new String("hello");
            System.out.println(s1 == s3);
            System.out.println(s1.equals(s3));
            
            char c[] = {'s', 'u', 'n', ' ', 'j', 'a', 'v', 'a'};
            String s4 = new String(c);
            String s5 = new String(c, 4, 3); // 数组, 下标, 长度
            System.out.println(s4 + '
    ' + s5);
            
            System.out.println(s4.charAt(1));
            System.out.println(s4.length());
            System.out.println(s4.indexOf("java"));
            
            System.out.println(s4.replaceAll("sun", "oracle"));
        }
    }
    package com.bjsxt.chap6;
    
    public class TestStringCase {
        public static void main(String[] args) {
            String s = "ABAabb$&^$#BAAb898B#@%aa";
            int cU = 0, cL = 0, cO = 0;
            for (int i = 0; i < s.length(); i++) {
                char c = s.charAt(i);
    
                if (c >= 'A' && c <= 'Z') {
                    cU++;
                } else if (c >= 'a' && c <= 'z') {
                    cL++;
                } else {
                    cO++;
                }
            }
    
            System.out.println("小写:" + cL);
            System.out.println("大写:" + cU);
            System.out.println("其他:" + cO);
            
            int lCount = 0, uCount = 0, oCount = 0;
            for (int i = 0; i < s.length(); i++) {
                char c = s.charAt(i);
                if (Character.isLowerCase(c)) {
                    lCount++;
                } else if (Character.isUpperCase(c)) {
                    uCount++;
                } else {
                    oCount++;
                }
            }
            
            System.out.println("小写:" + lCount);
            System.out.println("大写:" + uCount);
            System.out.println("其他:" + oCount);
            
            String ss = "sunjavahpjavaokjavajjavahahajavajavagoodjava";
            
            String sToFind = "java";
            int count = 0;
            int index = -1;
            
            while((index = ss.indexOf(sToFind)) != -1) {
                ss = ss.substring(index + sToFind.length());
                count ++;
            }
            
            System.out.println(count);
        }
    }
    
    package com.bjsxt.chap6;
    
    public class TestBuffer {
        public static void main(String[] args) {
            String s = "Mircosoft";
            char arr[] = {'a', 'b', 'c'};
            StringBuffer sb1 = new StringBuffer(s);
            sb1.append('/').append("IBM");
            System.out.println(sb1);
            StringBuffer sb2 = new StringBuffer("数字");
            for (int i = 0; i <= 9; i++) {
                sb2.append(i);
            }
            System.out.println(sb2);
            
            sb2.delete(8, 11).insert(0, arr);
            
            System.out.println(sb2);
            System.out.println(sb2.reverse());
        }
    }
    
    1.0 2.0 
    3.0 4.0 5.0 
    6.0 7.0 8.0 

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  • 原文地址:https://www.cnblogs.com/robbychan/p/3786910.html
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