java学习日记 StringBuffer类

public class StringBufferDemo1 {
    public static void main(String[] args) {
        StringBuffer sbu = new StringBuffer();
        sbu.append("Hello").append("World").append("!!!");
        System.out.println("修改之前："+sbu);
        System.out.println("修改之后："+change(sbu));

    }
    public static StringBuffer change(StringBuffer temp){
        return temp.append("jxqwc").append("gaile");
    }
}

修改之前：HelloWorld!!!
修改之后：HelloWorld!!!jxqwcgaile

public class StringBufferDemo1 {
    public static void main(String[] args) {
        StringBuffer sbu = new StringBuffer("Hello");
        System.out.println(sbu);
       }
}

public class StringBufferDemo1 {
    public static void main(String[] args) {
        StringBuffer sbu = new StringBuffer();
        sbu.append("Hello");
        System.out.println(sbu);
    }
}

public class StringBufferDemo1 {
    public static void main(String[] args) {
        StringBuffer sbu = new StringBuffer("Hello");
        String str = sbu.toString();
        System.out.println(sbu);
    }
}