Adding multiple values to a textView - Android

问题:

I'm currently trying to make a basic app that incorporates 4 toggle buttons and a textview. The idea is simple: When a button is pressed, the textview will show which buttons are currently being pressed. This can include multiple buttons (such as if, for example 1, 3, and 4 were pressed). Here's the code I've written for it:

TextView buttons;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    buttons = (TextView)findViewById(R.id.textView1);

    }

public void buttonPressed(View v){
    boolean check = ((ToggleButton)v).isChecked();

    int b1 = 1, b2 = 2, b3 = 3, b4 = 4;

    switch(v.getId()){
    case R.id.toggleButton1:
        if(check){
            buttons.setText("Buttons pressed: " + b1);
        }
        else{
            buttons.setText("Buttons pressed:");
        }
        break;
    case R.id.toggleButton2:
        if(check){
            buttons.setText("Buttons pressed: " + b2);
        }
        else{
            buttons.setText("Buttons pressed:");
        }
        break;
    case R.id.toggleButton3:
        if(check){
            buttons.setText("Buttons pressed: " + b3);
        }
        else{
            buttons.setText("Buttons pressed:");
        }
        break;
    case R.id.toggleButton4:
        if(check){
            buttons.setText("Buttons pressed: " + b4);
        }
        else{
            buttons.setText("Buttons pressed:");
        }
        break;
    default:
        break;

    }



}

Unfortunately, every time I run this program, the textview is overwritten, and I can't get it to validate that multiple buttons are pressed. All suggestions are welcome.

回答1:

If you want your textview always show number of ON buttons, I think you can do this way :

Keep tracks of your buttons

private ToggleButton[] btns = new ToggleButton[4];

In onCreate():

btn[0] = (ToggleButton)findViewById(R.id.toggleButton1);
btn[1] = (ToggleButton)findViewById(R.id.toggleButton2);
btn[2] = (ToggleButton)findViewById(R.id.toggleButton3);
btn[3] = (ToggleButton)findViewById(R.id.toggleButton4);

Then in your buttonPressed handler :

String text = "Buttons pressed: ";
for (int i = 0; i < 4; i++) {
    if (btn[i].isCheck()) {
        text += (i + 1) + ", ";
    }
}
buttons.setText(text);

回答2:

You need to use append() if you don't want to overwrite the text that is already there. So something like

public void buttonPressed(View v){
boolean check = ((ToggleButton)v).isChecked();

int b1 = 1, b2 = 2, b3 = 3, b4 = 4;

switch(v.getId()){
case R.id.toggleButton1:
    if(check){
        buttons.append("" + b1);
    }
    else{
        buttons.setText("Buttons pressed:");
    }
    break;

And you can just use buttons.setText("Buttons pressed"); once in onCreate() then append everything to that.