Question

抱歉问一个奇怪的问题，我是java的新手，我将制作一个Android应用程序，可以从c = a + b进行计数但它总是返回nullpointerexception

这是我的代码

public class Kreasi extends Activity {

    // Inisialisasi
    private EditText e1;
    private EditText e2;

    private Spinner s1;

    private Button b1;
    private Button b2;

    private TextView t1;
    private TextView t2;
    private TextView t3;
    private TextView t4;
    private TextView t5;

    public void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);
        setContentView(R.layout.kreasi);

        // INISIALISASI VARIABEL
        e1 = (EditText)findViewById(R.id.isiharga);
        e1 = (EditText)findViewById(R.id.isilaba);

        s1 = (Spinner)findViewById(R.id.spin);

        b1 = (Button)findViewById(R.id.process);
        b2 = (Button)findViewById(R.id.reset);

        t1 = (TextView)findViewById(R.id.hMax);
        t2 = (TextView)findViewById(R.id.angPokok);
        t3 = (TextView)findViewById(R.id.angSewa);
        t4 = (TextView)findViewById(R.id.angTotal);

        b1.setOnClickListener(new OnClickListener(){
            int a,b;
            @Override
            public void onClick(View v) {

                hideSoftKeyboard(b1);

                String aa,bb;

                aa = e1.getText().toString();
                bb = e2.getText().toString();

                a = Integer.valueOf(aa);
                b = Integer.valueOf(bb);

                int c = (int) (a + b);
                t1.setText(Integer.toString(c));

            }

        });

    }

    // Menyembunyikan Keyboard
    public void hideSoftKeyboard(Button btn) {
        btn.setInputType(0);
        InputMethodManager imm = (InputMethodManager) getSystemService(Context.INPUT_METHOD_SERVICE);
        imm.hideSoftInputFromWindow(btn.getWindowToken(), 0);
    }

    /*
    // Fungsi saat tombol process ditekan
    public void tombolprocess(){

        b1.setOnClickListener(new OnClickListener(){

            @Override
            public void onClick(View v) {

                hideSoftKeyboard(b1);

                aa = e1.getText().toString();
                bb = e2.getText().toString();

                Toast.makeText(getBaseContext(),"a="+aa +" b=" +bb,Toast.LENGTH_SHORT).show();

            }

        });

    }
    */
}

感谢任何建议

Answer 1

这是因为你没有传递e2的价值。

简单地改变：

e1 = (EditText)findViewById(R.id.isiharga);
e1 = (EditText)findViewById(R.id.isilaba);

到

e1 = (EditText)findViewById(R.id.isiharga);
e2 = (EditText)findViewById(R.id.isilaba);

Answer 2

您已将e1设置两次，您还需要设置e2，就像这样

e1 = (EditText)findViewById(R.id.isiharga);
e2 = (EditText)findViewById(R.id.isilaba);

总是空指针异常

2 个答案: