一:IllegalArgumentException非法参数类,这个类继承父类RuntimeException
1 public 2 class IllegalArgumentException extends RuntimeException
重载的几个构造方法都是直接调用父类的构造方法:
//无参数构造器,默认构造器 public IllegalArgumentException() { super(); } //参数为字符串String的构造器 public IllegalArgumentException(String s) { super(s); } //参数为String以及Throwable两个参数构造器 public IllegalArgumentException(String message, Throwable cause) { super(message, cause); } //参数为Throwable的构造器 public IllegalArgumentException(Throwable cause) { super(cause); } private static final long serialVersionUID = -5365630128856068164L;
RuntimeException类是直接继承extends Exception类
public class RuntimeException extends Exception { static final long serialVersionUID = -7034897190745766939L; public RuntimeException() { super(); } public RuntimeException(String message) { super(message); } public RuntimeException(String message, Throwable cause) { super(message, cause); } public RuntimeException(Throwable cause) { super(cause); }
Exception类:
public class Exception extends Throwable { static final long serialVersionUID = -3387516993124229948L; public Exception() { super(); } public Exception(String message) { super(message); } public Exception(String message, Throwable cause) { super(message, cause); } public Exception(Throwable cause) { super(cause); } }
而Exception类是继承Throwable类
1 //无参数构造器 2 public Throwable() { 3 fillInStackTrace(); 4 } 5 6 //调用native方法,底层是c或者c++语言实现 7 public synchronized native Throwable fillInStackTrace();
//参数为String的构造器,描述异常信息 public Throwable(String message) { fillInStackTrace(); detailMessage = message; } private String detailMessage;
1 //参数为String以及Throwable的构造器 2 public Throwable(String message, Throwable cause) { 3 fillInStackTrace(); 4 detailMessage = message; 5 this.cause = cause; 6 }
//参数为Throwable的构造器 public Throwable(Throwable cause) { fillInStackTrace(); detailMessage = (cause==null ? null : cause.toString()); this.cause = cause; }
再来看一下Throwable中的其他的方法:
//异常的详细信息,就是在构造方法中封装的message public String getMessage() { return detailMessage; }
//直接调用getMessage方法,返回的也是异常的描述信息 public String getLocalizedMessage() { return getMessage(); }
//获取这个异常对象,因为这个cause异常对象初始化的时候 是this,就是它本身,所以如果没有变,就是null,否则是cause private Throwable cause = this; public Throwable getCause() { return (cause==this ? null : cause); }
二:自定义异常类
如果我们想要自定义异常类,只需要继承RuntimeException或者Exception类,然后
在构造方法中调用父类的构造方法就可以了。