public class ToStringBuilder extends Object Assists in implementing Object.toString() methods.This class enables a good and consistent toString() to be built for any class or object. This class aims to simplify the process by:allowing field names handling all types consistently handling nulls consistently outputting arrays and multi-dimensional arrays enabling the detail level to be controlled for Objects and Collections handling class hierarchies To use this class write code as follows: public class Person { String name; int age; boolean smoker;
...
public String toString() { return new ToStringBuilder(this). append("name", name). append("age", age). append("smoker", smoker). toString(); } }
This will produce a toString of the format: Person@7f54[name=Stephen,age=29,smoker=false]To add the superclass toString, use appendSuper(java.lang.String). To append the toString from an object that is delegated to (or any other object), use appendToString(java.lang.String).Alternatively, there is a method that uses reflection to determine the fields to test. Because these fields are usually private, the method, reflectionToString, uses AccessibleObject.setAccessible to change the visibility of the fields. This will fail under a security manager, unless the appropriate permissions are set up correctly. It is also slower than testing explicitly.A typical invocation for this method would look like: public String toString() { return ToStringBuilder.reflectionToString(this); }
You can also use the builder to debug 3rd party objects: System.out.println("An object: " + ToStringBuilder.reflectionToString(anObject));
The exact format of the toString is determined by the ToStringStyle passed into the constructor.
extends Object
Assists in implementing Object.toString() methods.This class enables a good and consistent toString() to be built for any class or object. This class aims to simplify the process by:allowing field names
handling all types consistently
handling nulls consistently
outputting arrays and multi-dimensional arrays
enabling the detail level to be controlled for Objects and Collections
handling class hierarchies
To use this class write code as follows: public class Person {
String name;
int age;
boolean smoker;
...
public String toString() {
return new ToStringBuilder(this).
append("name", name).
append("age", age).
append("smoker", smoker).
toString();
}
}
This will produce a toString of the format: Person@7f54[name=Stephen,age=29,smoker=false]To add the superclass toString, use appendSuper(java.lang.String). To append the toString from an object that is delegated to (or any other object), use appendToString(java.lang.String).Alternatively, there is a method that uses reflection to determine the fields to test. Because these fields are usually private, the method, reflectionToString, uses AccessibleObject.setAccessible to change the visibility of the fields. This will fail under a security manager, unless the appropriate permissions are set up correctly. It is also slower than testing explicitly.A typical invocation for this method would look like: public String toString() {
return ToStringBuilder.reflectionToString(this);
}
You can also use the builder to debug 3rd party objects: System.out.println("An object: " + ToStringBuilder.reflectionToString(anObject));
The exact format of the toString is determined by the ToStringStyle passed into the constructor.
private Integer id;
private String name;
private String password; // ... public String toString() {
return new ToStringBuilder(this, ToStringStyle.SIMPLE)
.append(id)
.append(name)
.append(password);
} public static void main(String[] args) {
System.out.println(user);
}
}如果运行上面的main方法的话,user的属性就可以漂亮的被打印出来了。
double real,image;
public MyComplex(){};
public MyComplex(double r,double i){
real=r;
image=i;
}
double getReal(){return real;}
double getImage(){return image;}
MyComplex jia(MyComplex a){
MyComplex temp=new MyComplex();
temp.image=image+a.image;
temp.image=image+a.image;
return temp;
}
MyComplex jian(MyComplex a){
MyComplex temp=new MyComplex();
temp.image=image-a.image;
temp.image=image-a.image;
return temp;
}
MyComplex chen(MyComplex a){
MyComplex temp=new MyComplex();
temp.image=image*a.image-image*a.image;
temp.image=real*a.image+image*a.real;
return temp;
}
MyComplex chu(MyComplex a){
MyComplex temp=new MyComplex();
temp.image=(image*a.image+image*a.image)/(a.real*a.real+a.image*a.image);
temp.image=(image*a.real-real*a.image)/(a.real*a.real+a.image*a.image);
return temp;
}
public boolean equals(MyComplex a){
if(real==a.real&&image==a.image)
return true;
else
return false;
}
public String toString(){
String info=new String();
if(this.getReal()==0)
info=String.valueOf(this.getImage())+'i';
else if(this.getImage()==0)
info=String.valueOf(this.getReal());
else if(this.getImage()<0)
info=String.valueOf(this.getReal())+String.valueOf(this.getImage())+'i';
else
info=String.valueOf(this.getReal())+'+'+String.valueOf(this.getImage())+"i";
return info;
}
}class MyComplexTest{
public static void main(String[] args){
MyComplex m1=new MyComplex(1,-2);
MyComplex m2=new MyComplex(1,-2);
MyComplex m3=new MyComplex(1,-1);
MyComplex m4=new MyComplex(7.8,-0.8999996);
MyComplex m5=new MyComplex(-1,16.9);
if(m1==m2)
System.out.println("m1==m2=ture");
else
System.out.println("m1==m2=false");
if(m1.equals(m2))
System.out.println("m1.equals(m2)=ture");
else
System.out.println("m1.equals(m2)=false");
System.out.println(m4);
System.out.println(m5);
}
}
简单的说Stringbuilder可以自由改变字符串,而String不能。。具体效率什么的你可以上网search下;
其实toString和toStringBuilder方法相似,只是在返回值上有些区别。前者返回类型为String类型,后者为StringBuilder类型,在使用时被重写后可以灵活的改变返回值的长度。
楼上的是通过重写toString()方法,来实现返回指定的单个字符串。如果变为很多,而且中间还要加一些重复的特殊符号(如Person@14576877[name=pengzhoushuo,age=25,sex=true]中的@,[,],=),那就需要用到toStringBuilder了。当然前者也可以实现,只是麻烦些,而且容易出错,效率低。
呵呵,希望能对你有帮助!