如何检查按钮是否被单击

Question

I have to check whether the button is clicked or not.if clicked application has to do one task and if not, application has to do another task. I tried to do this, but I am getting no connection error which I have put at the end of the code in catch block.

 protected void onCreate(Bundle savedInstanceState) {
    PracticeVO practiceObj;

    try {

        setTitle("Klarity");
        setPrefBtn = (Button) findViewById(R.id.setPrefBtn);

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

        /*
         * asynchronous calls
         */

        StrictMode.ThreadPolicy policy = new     StrictMode.ThreadPolicy.Builder()
                .permitAll().build();
        StrictMode.setThreadPolicy(policy);

        final ConnectionHelper con = new ConnectionHelper();
        /*
         * It will connect to DB and fetches the Practice Information
         */
        if (Btnclicked == false) {

            String allPracticesStr = null;

here I have set the boolean variable 'Btnclicked' true.

 setPrefBtn.setOnClickListener(new View.OnClickListener() {
                public void onClick(View v) {
                    Btnclicked=true;
                    Intent setPrefIntent = new Intent(KlarityHome.this,
                            SetPreferences.class);
                    startActivity(setPrefIntent);

                }
            });

But After executing this The cursor is directly goin here and displaying 'no connection'.

catch (Exception ex) {
        Context context = getApplicationContext();
        CharSequence text = "There is some error in application";
        int duration = Toast.LENGTH_LONG;

        Toast toast = Toast.makeText(context, text, duration);
        toast.show();
        System.out.println("no connection");
    }

}

Anyone has solution on this.

Answer 1

as you said

"the button is clicked or not.if clicked application has to do one task and if noapplication has to do another task" so, if i were you, i'll put 2 radio buttons, every one with the text of the task you want to do, and add a listener for them, like this:

radiobutton1.setOnCheckedChangeListener(new RadioButton.OnCheckedChangeListener() {
        @Override
        public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
            radiobutton2.setChecked(false);
        }
    });

radiobutton2.setOnCheckedChangeListener(new RadioButton.OnCheckedChangeListener() {
            @Override
            public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
                radiobutton1.setChecked(false);
            }
    });

and last, in the button do the task you want to do:

    Button.setOnClickListener(new Button.OnClickListener() {
                public void onClick(View v) {
    if(radiobutton1.isChecked){
    //do task 1
}else{
//do task2}
    }
    });

Answer 2

You are getting an NPE(NullPointerException) since you havent initialised Btnclicked in your code at the time of usage.ie you are checking whether Btnclicked is false like

if (Btnclicked == false) {

But at the time of this checking, the value of Btnclicked is null and hence an NPE.

So to get rid of this, you just add either

Btnclicked=true;

or

Btnclicked=false;

before the if loop according to your logic.

OR

or just replace the declaration from Boolean Btnclicked; to Boolean Btnclicked=false;

Hope this helps.

Answer 3

Remove Btnclicked you don't need that. OnClickListner is meant for what you're trying to do. The code which you want to run when button is not pressed put it before

//When button is not pressed
setPrefBtn.setOnClickListener(new View.OnClickListener() {
                public void onClick(View v) {
                    //When button is pressed
                }
            });

And the code which you want to run when the button is clicked place it inside the onClick(){}