java - Null Pointer Exception: null error -

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इस सवाल का पहले से ही एक उत्तर है: < / P>

  • 12 जवाब

मेरे पास यह हैश सेट कोड है और जब मैं उस पर मेरी संकलन पद्धति को चलाने की कोशिश करता हूं तो मुझे नल पॉइंटर अपवाद मिलता है: उस पर नल की त्रुटि। यहां कोड है: 

  निजी शून्य इनिट किवेड्स () {कीवर्ड = नया हैशसेट & lt; स्ट्रिंग & gt; (); keywords.add ( "अंतिम"); keywords.add ( "पूर्णांक"); keywords.add ( "जबकि"); keywords.add ( "अगर"); keywords.add ( "और"); keywords.add ( "प्रिंट"); } निजी बूलियन आईआईडेंट (स्ट्रिंग टी) {यदि (कीवर्डसीटेंशन्स (टी)) {*** // यह लाइन है मैं त्रुटि *** रिटर्न झूठी मिलती है; } और अगर (टी! = नल & amp; amp; t.length () & gt; 0 & amp; amp; amp; amp; amp; & amp; amp; amp; amp; amp; & amp; amp; amp; amp; चरित्र। } अन्य {वापसी झूठी; }}

इस त्रुटि के साथ साथ जाने वाली अन्य पंक्तियां हैं: 

  सार्वजनिक शून्य संकलन प्रोग्राम () {System.out.println ("compiling" फ़ाइल का नाम); जबकि (theToken! = Null) {if (बराबर ("टोकन", "int") || बराबर (टोकन, "अंतिम")) {compileDeclaration (सच); } Else {compileFunction (); // यह लाइन उपरोक्त त्रुटि के साथ त्रुटि दे रही है}} cs.emit (मशीन। एचएएलटी); IsCompiled = सच है; } निजी शून्य संकलनफंक्शन () {स्ट्रिंग fname = theToken; Int entryPoint = cs.getPos (); अगर (बराबर (fname, "मुख्य")) {cs.setEntry (entryPoint); } अगर (आइआइंडेंट (टूटीन)) theToken = t.token (); *** // यह रेखा एक त्रुटि दे रही है *** और टी। आतंक ("पहचानकर्ता की अपेक्षा, मिला" + टोकन); symTable.allocProc (fname, entryPoint); स्वीकार करें ("("); संकलितपरमलिस्ट (); स्वीकार (")"); compileCompound (सही); अगर (बराबर (fname, "मुख्य")) cs.emit (मशीन। एचएएलटी); Else cs.emit (मशीन। आरईटी); }

या तो कीवर्ड या t शून्य है डीबगर या प्रिंट स्टेटमेंट्स का उपयोग करना यह निर्धारित करना बहुत आसान होना चाहिए। यदि कीवर्ड शून्य है, तो मुझे लगता है कि init कीवर्ड () अभी तक नहीं बुलाया गया है।


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