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POJava: Copy Constructor not going as planned
 

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  1. POJava: Copy Constructor not going as planned
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    <p>I have a bit of a problem. I'm making a Finite Automata checker. Given an input, and the DFA, does it end on a accepting state.</p> <p>My problem is creating a new DFA_State from another's target.</p> <pre><code>DFA_State state0, state1, curr_state, init_state, temp; //fine, I think state0 = new DFA_State(); state1 = new DFA_State(); state0 = new DFA_State("State 0",true, state0, state1); //fine, I think init_state = new DFA_State(state0); //fine, I think </code></pre> <p>but, this bit is throwing up problems.</p> <pre><code>temp = new DFA_State(curr_state.nextState(arr1[i])); * * curr_state = new DFA_State(temp); </code></pre> <p>Thanks for any help, Dave</p> <p>Edit: God I was retarded when I did this, AFAIK, I just wasn't thinking straight, added methods to set the values to the DFA_State object.</p> <pre><code>//in DFA_State class public void set(DFA_State on_0, DFA_State on_1, Boolean is_accepting, String name){ this.on_0 = on_0; this.on_1 = on_1; this.is_accepting = is_accepting; this.name = name; } //in main DFA_State state0, state1, curr_state; state0 = new DFA_State(); state1 = new DFA_State(); state0.set(state0, state1, false, "State 0"); state1.set(state1, state0, true, "State 1"); curr_state = state0;//initial state //iterate across string input changing curr_state depending on char c curr_state = getNextState(c); //at end if(curr_state.isAccepting()) System.out.println("Valid, " + curr_state.getName() + " is accepting); else System.out.println("Invalid, " + curr_state.getName() + " is not accepting); </code></pre>
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    1. USdave.8bit
    1. USdave.8bit
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    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
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    1. COI do not get it
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      1. POJava: Copy Constructor not going as planned
      1. USMarianP
    2. COThis looks like homework; please state that in the question. Also, can you be more specific about what "throwing up problems" means? (is there a stack trace, etc?)
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      1. POJava: Copy Constructor not going as planned
      1. USmpontillo
    3. COyes it's homework, Exception in thread "main" java.lang.NullPointerException
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      1. USdave.8bit
 

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