[英]Does node-java allow anonymous functions to be passed to java as parameters?
我希望能夠使用node-java( https://github.com/joeferner/node-java )將匿名函數從Javascript傳遞給Java。 這是Java代碼的示例:
public class Example {
public Example() {
}
public interface Callback {
public void f();
}
public void method1(boolean flag, Callback c) {
System.out.println("flag value: " + flag);
if (flag) {
System.out.println("About to call callback");
c.f();
System.out.println("Called callback");
}
else {
System.out.println("Didn't call callback");
}
}
}
這是我想從Javascript調用的方式:
例1:
var java = require('java');
java.classpath.push('test8');
var Example = java.import('Example');
var anonF = () => {
console.log("Hello from callback!");
}
var e = new Example();
e.method1Sync(true, anonF);
這將引發錯誤:
flag value: true
About to call callback
/Users/chris.prince/Desktop/Tests/test.js:11
e.method1Sync(true, anonF);
^
Error: Error running instance method
java.lang.NullPointerException
at Example.method1(Example.java:14)
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 Error (native)
at Object.<anonymous> (/Users/chris.prince/Desktop/Tests/test.js:11:3)
at Module._compile (module.js:556:32)
at Object.Module._extensions..js (module.js:565:10)
at Module.load (module.js:473:32)
at tryModuleLoad (module.js:432:12)
at Function.Module._load (module.js:424:3)
at Module.runMain (module.js:590:10)
at run (bootstrap_node.js:394:7)
at startup (bootstrap_node.js:149:9)
我也嘗試過將Javascript模塊作為參數傳遞,但也無法使其正常工作。
范例2:
在文件“ theModule.js”中:
exports.f = function() {
console.log("Hello From The Module!");
};
這是調用Javascript代碼:
var theModule = require('./theModule');
var java = require('java');
java.classpath.push('test8');
var Example = java.import('Example');
var e = new Example();
e.method1Sync(true, theModule);
第二個示例也失敗並顯示錯誤:
flag value: true
About to call callback
/Users/chris.prince/Desktop/Tests/test.js:8
e.method1Sync(true, theModule);
^
Error: Error running instance method
java.lang.NullPointerException
at Example.method1(Example.java:14)
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 Error (native)
at Object.<anonymous> (/Users/chris.prince/Desktop/Tests/test.js:8:3)
at Module._compile (module.js:556:32)
at Object.Module._extensions..js (module.js:565:10)
at Module.load (module.js:473:32)
at tryModuleLoad (module.js:432:12)
at Function.Module._load (module.js:424:3)
at Module.runMain (module.js:590:10)
at run (bootstrap_node.js:394:7)
at startup (bootstrap_node.js:149:9)
思考?
雖然有點晚,但我將添加我的答案:
您是否嘗試將代理用於Callback
接口? 我沒有親自運行此代碼,但它看起來應該像這樣:
var java = require('java');
java.classpath.push('test8');
var Example = java.import('Example');
var myCallbackProxy = java.newProxy('Callback', {
f: function () {
console.log("Hello from callback!");
}
});
var e = new Example();
e.method1Sync(true, myCallbackProxy);
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