Java StringBuilder两个常用方法append()和toString()

创建方式

1. StringBuilder builder = new StringBuilder();//变量的值是"", 输出不是null
2. StringBuilder builder = new StringBuilder();
builder.append(value);//value可以是任何类型append()返回值是StringBuilder

样例

public class StringBuilderT {
    public static void main(String[] args) {

        StringBuilder builder = new StringBuilder();
        StringBuilder builder1 = new StringBuilder();
        builder1 = builder.append("abcd");
        System.out.println("builder="+builder+" "+"builder1="+builder1);
        System.out.println(builder==builder1);//结果为true，说明两个的引用是一样的
        builder.append(88);
        builder.append("fgag");
        builder.append('好');
        builder.append(builder);//传对象
        builder.append(1.2);
        System.out.println(builder);
    }
}

String和StringBuilder相互转换

• 用StringBuilder的构造方法StringBuilder(String str)或append(),把String转换成StringBuilder
• 用toString()方法把StringBuilder转换为String

用例

public class StringBuilderT {
    public static void main(String[] args) {
        String s = "354hh";
        StringBuilder builder = new StringBuilder(s);
        StringBuilder builder1 = new StringBuilder();
        builder1.append(s);
        System.out.println("builder="+builder+" "+"builder1="+builder1);
        StringBuilder builder2 = new StringBuilder();
        builder2.append(545454.323332);
        String s1 = builder2.toString();//toString返回值是String
        System.out.println("s1="+s1);

    }
}