异常代码的各种情况

Try Catch Finally Return 执行顺序

 public String testTryCatchFinally() {
     try {
         System.out.println("try开始执行");
         System.out.println("try执行完了");
         return "try中的返回值";
     } catch (Exception e) {
         System.out.println("捕获到的异常");
     } finally {
         System.out.println("finally执行完了");
     }
     return "最终中的返回值";
 }

try开始执行
try执行完了
finally执行完了
try中的返回值

public String testTryCatchFinally2() {
    try {
        System.out.println("try开始执行");
        String str = null;
        str.length();
        System.out.println("try执行完了");
        return "try中的返回值";
    } catch (Exception e) {
        System.out.println("捕获到的异常");
    } finally {
        System.out.println("finally执行完了");
    }
    return "最终中的返回值";
}

try开始执行
捕获到的异常
finally执行完了
最终中的返回值

Throw 几种情况第0种

public class Person {
    public String high() {
        int a = 5;
        a = a / 0;
        return "tall";
    }
}


@Test
public void test11() {
    Person person = new Person();
    person.high();
}

java.lang.ArithmeticException: / by zero
	at exception.throwandthrows.Person.high(Person.java:14)
	at exception.throwandthrows.ThrowsAndThrowMainTest.test11(ThrowsAndThrowMainTest.java:63)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.junit.runners.model.frameworkMethod$1.runReflectiveCall(frameworkMethod.java:50)
	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
	at org.junit.runners.model.frameworkMethod.invokeExplosively(frameworkMethod.java:47)
	at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
	at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)
	at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
	at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
	at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
	at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
	at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
	at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
	at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:69)
	at com.intellij.rt.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:33)
	at com.intellij.rt.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:235)
	at com.intellij.rt.junit.JUnitStarter.main(JUnitStarter.java:54)
Process finished with exit code -1

第1种

public class Person {
    public String weight(int num) {
        if (num > 90) {
            throw new MyException(400, "overWeight");
        }
        return "light";
    }
}

@Test
public void test(){
    Person person = new Person();
    person.weight(91);
}

exception.throwandthrows.MyException: overWeight
	at exception.throwandthrows.Person.weight(Person.java:7)
	at exception.throwandthrows.ThrowsAndThrowMainTest.test(ThrowsAndThrowMainTest.java:19)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.junit.runners.model.frameworkMethod$1.runReflectiveCall(frameworkMethod.java:50)
	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
	at org.junit.runners.model.frameworkMethod.invokeExplosively(frameworkMethod.java:47)
	at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
	at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)
	at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
	at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
	at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
	at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
	at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
	at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
	at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:69)
	at com.intellij.rt.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:33)
	at com.intellij.rt.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:235)
	at com.intellij.rt.junit.JUnitStarter.main(JUnitStarter.java:54)
	
Process finished with exit code -1

第2种

可以包装一下而已

public class Person {
    public String weight(int num) {
        if (num > 90) {
            throw new MyException(400, "overWeight");
        }
        return "light";
    }
}

@Test
public void test2(){
    try {
        Person person = new Person();
        person.weight(91);
    } catch (Exception e) {
        System.out.println(e.getMessage());
        e.printStackTrace();
    }
}

overWeight
exception.throwandthrows.MyException: overWeight
	at exception.throwandthrows.Person.weight(Person.java:7)
	at exception.throwandthrows.ThrowsAndThrowMainTest.test2(ThrowsAndThrowMainTest.java:25)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.junit.runners.model.frameworkMethod$1.runReflectiveCall(frameworkMethod.java:50)
	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
	at org.junit.runners.model.frameworkMethod.invokeExplosively(frameworkMethod.java:47)
	at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
	at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)
	at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
	at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
	at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
	at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
	at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
	at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
	at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:69)
	at com.intellij.rt.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:33)
	at com.intellij.rt.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:235)
	at com.intellij.rt.junit.JUnitStarter.main(JUnitStarter.java:54)

Process finished with exit code 0

第3种

public class Person {
    public String weight(int num) {
        if (num > 90) {
            throw new MyException(400, "overWeight");
        }
        return "light";
    }
}

@Test
public void test3() {
    try {
        Person person = new Person();
        person.weight(91);
    } catch (MyException e) {
        System.out.println(e.getCode() + e.getMessage());
    } catch (Exception e) {
        System.out.println(e.getMessage());
        throw new MyException(500, e.getMessage());
    }
}

400overWeight

Process finished with exit code 0

第4种

public class Person {
    public String weight(int num) {
        if (num > 90) {
            throw new MyException(400, "overWeight");
        }
        return "light";
    }
}

public class Doctor {
    public void check() {
        try {
            Person person = new Person();
            person.weight(91);
        } catch (MyException e) {
            throw e;
        } catch (Exception e) {
            throw new MyException(500, e.getMessage());
        }
    }
}

@Test
public void test4() {
    try {
        Doctor doctor = new Doctor();
        doctor.check();
    } catch (MyException e) {
        System.out.println(e.getCode() + e.getMessage());
    } catch (Exception e) {
        System.out.println(e.getMessage());
        throw new MyException(500, e.getMessage());
    }
}

400overWeight

Process finished with exit code 0

第5种

public class Person {
    public String high() {
        int a = 5;
        a = a / 0;
        return "tall";
    }
}

public class Doctor {
    public void check2() {
        try {
            Person person = new Person();
            person.high();
        } catch (MyException e) {
            throw e;
        } catch (Exception e) {
            throw new MyException(500, e.getMessage());
        }
    }
}

@Test
public void test12() {
    try {
        Doctor doctor = new Doctor();
        doctor.check2();
    } catch (MyException e) {
        System.out.println(e.getCode() + e.getMessage());
    } catch (Exception e) {
    }
}

500/ by zero

Process finished with exit code 0

第6种

public String weight(int num) {
    if (num > 90) {
        throw new MyException(400, "overWeight");
    }
    return "light";
}

public class Doctor {
    public void check3() {
        Person person = new Person();
        person.weight(91);
    }
}

@Test
public void test13() {
    try {
        Doctor doctor = new Doctor();
        doctor.check3();
    } catch (MyException e) {
        System.out.println(e.getCode() + e.getMessage());
    } catch (Exception e) {
        System.out.println(e.getMessage());
    }
}

400overWeight

Process finished with exit code 0

第7种

public class Person {
    public String high() {
        int a = 5;
        a = a / 0;
        return "tall";
    }
}

public class Doctor {
    public void check4() {
        Person person = new Person();
        person.high();
    }
}

@Test
public void test14() {
    try {
        Doctor doctor = new Doctor();
        doctor.check4();
    } catch (MyException e) {
        System.out.println(e.getCode() + e.getMessage());
    } catch (Exception e) {
        System.out.println(e.getMessage());
    }
}

异常代码的各种情况

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