Java, Common substring of two string in JAVA

public String getLongestCommonSubstring(String str1, String str2) { int m = str1.length(); int n = str2.length(); int max = 0; int[][] dp = new int[m][n]; int endIndex=-1; for(int i=0; i<m; i++){ for(int j=0; j<n; j++){ if(str1.charAt(i) == str2.charAt(j)){ // If first row or column if(i==0 || j==0){ dp[i][j]=1; }else{ // Add 1 to the diagonal value dp[i][j] = dp[i-1][j-1]+1; } if(max < dp[i][j]) { max = dp[i][j]; endIndex=i; } } } } // We want String upto endIndex, we are using endIndex+1 in substring. return str1.substring(endIndex-max+1,endIndex+1); } }