title: create decrease and increase button listener for number picker in android
body: <p>i want to make custom number picker. it have two buttons; previous and next. when the user click on next button, the number will increase one number and when the user click on the previous button, the number will decrease one number.</p>
  
  <p>i only success with the next button but i dont have the idea to make it with previous button. does anyone have the idea to help me with it?</p>
  
  <p>this is my code</p>
  
  <pre><code>ageEdit = (EditText) findViewById(R.id.editText7);
      ageEdit.setHint("0");
      ageEdit.setHighlightColor(000000);
      ageNext = (Button) findViewById(R.id.button2);
      ageNext.setOnClickListener(new OnClickListener(){   
          int age = 0;
          @Override
          public void onClick(View arg0) {
              age++;
              String ageText = Integer.toString(age);
              ageEdit.setHint(ageText);
          }
      });
      agePrev = (Button) findViewById(R.id.Button1);
      agePrev.setOnClickListener(new OnClickListener(){
          public void onClick(View v){
              //what should i put in here
          }
      });
  </code></pre>
  
  <p>this is what the interface looks like
  <img src="https://i.stack.imgur.com/HhHtN.png" alt="enter image description here"></p>