问当抛出一个新的NPE时，不需要Java的“抛出”子句？为什么添加“抛出异常”会导致编译错误？

EN

// 1
public void throwNPE() {
    throw new NullPointerException();
}

// 2
public void throwNPEWithGenericClause() throws Exception {
    throw new NullPointerException();
}

// 3
public void throwNPEWithNPEClause() throws NullPointerException {
    throw new NullPointerException();
}

// 4
public void throwNPEWithIAEClause() throws IllegalArgumentException {
    throw new NullPointerException();
}

// 5
public void callThrowNPE() {
    throwNPE();
}

// 6
public void callThrowNPEWithGenericClause() {
    throwNPEWithGenericClause(); // COMPILATION ERROR
}

// 7
public void callThrowNPEWithNPEClause() {
    throwNPEWithNPEClause();
}

// 8
public void callThrowNPEWithIAEClause() {
    throwNPEWithIAEClause();
}