String

package TestArray;
/**
 * String类：不可变字符序列
 * @author 4090039qrh
 *
 */

public class TestString {
    public static void main(String[] args) {
        //方法1
        String str="abcdb";
        String str1="abcd";
        //方法2
        char c[]= {'a','b','c','d'};
        String a=new String(c);
        String a1=new String(c);
        
        System.out.println(str);//abcd
        System.out.println(a);//abcd
        
        //charAt() 显示index所在的值
        System.out.println(str.charAt(2));//c
        
        //indexOf 显示值所在的index
        System.out.println(str.indexOf("b"));//1
        System.out.println(str.lastIndexOf("b"));//4
        
        //equals 判断值是否相等
        System.out.println(str.equals(str1));//true
        System.out.println(str.equals(a));//true
        System.out.println(a.equals(a1));//true
        
        //== 判断所在内存位置是否相等
        System.out.println(str==str1);//true
        System.out.println(str==a);//false
        System.out.println(a==a1);//false
        
        //substring(1)取字符串
        //System.out.println(str.substring(-3));//StringIndexOutOfBoundsException
        System.out.println(str.substring(1));//bcd
        
        
        //replace 替换
        System.out.println(str.replace('b', 'h'));//ahcd
        
        //split 分隔符        
        String str2="abcd,erty,klpo";
        String strArray[]=str2.split(",");
        for(int i=0;i<strArray.length;i++) {
            System.out.println(strArray[i]);
        }
        
        //trim 去掉首尾
        String str3=" er kl ";
        String str4=str3.trim();
        System.out.println(str4.length());//5
        
        //equalsIgnoreCase 忽略大小写
        System.out.println("abc".equalsIgnoreCase("Abc"));//true
        
        //startsWith
        System.out.println("abc".startsWith("ab"));//true
        
        //endsWith
        System.out.println("abc".endsWith("c"));//true
        
        //toLowerCase
        System.out.println("Abc".toLowerCase());//true
        
        //toUpperCase
        System.out.println("Abc".toUpperCase());//true
        
        
        String x1="a";
        for(int i=0;i<5;i++) {
            x1+=i;
        }
        System.out.println(x1);//a01234  6个对象
        
        String x2=new String("a");
        for(int i=0;i<5;i++) {
            x2+=i;
        }
        System.out.println(x2);//a01234  7个对象
        
        
        
                
        
    }
    

}